Steel Construction 1/2021

1

Steel Construction

Volume 14 February 2021 ISSN 1867-0520

Design and Research

– Update on the revision of EC3 – Genoa San Giorgio Bridge – Numeric modelling of new semi-rigid joints with cyclic loads – Factors affecting cyclic behaviour of buckling-restrained plate shear wall – Wavelets for describing cellular beam behaviour – Tradition and modernity in Japanese steel-glass structure

00_STCO_0121_Buch.indb 1

03.02.21 11:15

Prof. Markus Knobloch, Prof. Ulrike Kuhlmann, Prof. Andreas Taras et al.

Structural member stability in the second generation of Eurocode 3 26 March 2021 10.00–12.00 a.m. CET With a series of Online Live Seminars (OLS) ECCS Steel Construction (STCO) journal presents international keynote speakers with up to date topics. Partner of the STCO OLS series is the European Convention for Constructional Steelworks (ECCS). The online lecture takes up to 1.5 hours. Following the speakers are available for questions and answers.

STCO OLS #2 will be given by Prof. Markus Knobloch, Ruhr-University Bochum, Prof. Ulrike Kuhlmann, Stuttgart University and Prof. Andreas Taras, ETH Zurich – supported by Anna-Lena Bours and Fabian Jörg – with a keynote Structural member stability in the second generation of Eurocode 3 at 26 March 2021 10.00 to 12.00 a.m. CET. The keynote is based on a two part paper by Knobloch, M.; Bureau, A.; Kuhlmann, U.; da Silva, L. S.; Snijder, H. H.; Taras, A.; Bours, A.-L.; Jörg, F. Structural member stability verification in the new Part 1-1 of the second generation of Eurocode 3,

Part 1: Evolution of Eurocodes, background to partial factors, cross-section classification and structural analysis (DOI 10.1002/ stco.202000016), Part 2: Member buckling design rules and further innovations. (DOI 10.1002/ stco.202000027), which had been published in Steel Construction 13 (2020) issues 2 and 3.

Registration www.ernst-und-sohn.de/stco-seminar

Fees 39 €* (regular) 29 €* (ECCS/national associations members)

www.ernst-und-sohn.de/stco-seminar * Excl. VAT. The General Terms and Conditions of the Akademie der Ingenieure apply.

STCO-OLS-2-Knobloch.indd 22 00_STCO_0121_Buch.indb 2

08.01.2021 12:03:46 03.02.21 11:15

Content Steel Construction 1/21 The building of the San Giorgio bridge in Genoa re-establishes the connection between autoroutes A10 and A7 after the tragic event of the Morandi bridge collapse of 14 August 2018.

The bridge deck layout required the use of a torsionally rigid section. This was achieved, in ­particular, with two longitudinal beams spaced 7.00 m apart, a curved, calendared soffit and a top slab made of composite concrete.

The new bridge was opened on 3 August 2020, finally revealing the idea of the architect, Renzo Piano: A big, white vessel moored in the valley, a bridge that enters a dialogue with the sea, with the wind, with light, a structure that encourages builders to continue building bridges as links between territories and symbols of union. (Sarcina, G. et al., pp. 14–21)

EDITORIAL

1

Enrique Mirambell The convenient equilibrium between the development and updating of a normative code, research and ­engineering practice

DESIGN & RESEARCH

Ulrike Kuhlmann, Christina Schmidt-Rasche, Fabian Jörg, Vahid Pourostad, Jennifer Spiegler, Mathias Euler 2 Update on the revision of Eurocode 3

Gioacchino Sarcina, Francesco Poltronieri, Marco Raccagni, Siro Dal Zotto, Lorenzo Sartori, Vito Cardella, Andrea Morbin 14 Genoa San Giorgio Bridge

Abdulkadir Cüneyt Aydin, Aysan Ardalani, Mahyar Maali, Mahmut Kiliç 22 Numeric modelling of innovative semi-rigid connections under ­cyclic loading

Ali Munesi, Mohammadkazem Sharbatdar, Majid Gholhaki 35 An investigation into the factors influencing the cyclic behaviour of buckling-restrained steel plate shear walls

Komal Rajana, Andrés Alonso-Rodríguez, Konstantinos Daniel Tsavdaridis 47 A wavelet-based approach for describing the mechanical ­behaviour of cellular beams

Ewa Maria Kido, Zbigniew Cywiński, Hidetoshi Kawaguchi 55 Tradition and modernity in the structural art of steel-glass ­structures in Japan STEEL CONSTRUCTION NEWS

65

65 ECCS news 71 Events

Volume 14 February 2021, No. 1 ISSN 1867-0520 (print) ISSN 1867-0539 (online)

A4

PRODUCTS & PROJECTS

http://wileyonlinelibrary.com/journal/stco Steel Construction is indexed in Elsevier´s Scopus CiteScore 2019: 1.2

Journal for ECCS members

www.ernst-und-sohn.de/steel-construction

00_STCO_0121_Buch.indb 3

03.02.21 11:15

PRODUCTS & PROJECTS

ADVERT

Noise-reduced expansion joints with special “tunneling” for new bridge in Gothenburg

Fig. 1

The new Hisingsbron in Gothenburg. Visible in the background: the previous bridge.

Gothenburg. A streetcar running on a bridge is not uncommon.

However, this presents a challenge in Gothenburg since long ramps lead to the bridge construction. The required expansion joints between the structural sections have to be watertight and noisereduced and must be usable for all road users in the streetcar track area. MAURER developed a customized solution for the roadway expansion joints with a length of up to 43 m.

In the city center of Gothenburg, the Götaälvbron has been spanning the river Göta since 1939. The most important bridge of Gothenburg leads directly to the city center, but the bascule bridge will vanish soon. Only a few meters next to it, the Hisingsbron has been under construction since 2017, named after the island located north of the bridge. While the previous Götaälvbron with its huge clearance height gives the impression of a break in the city, the Hisingsbron which is lower in height is intended to form part of a new urban life: with broad pedestrian paths, bikeways and scenic outlook areas as well as connections to the riverwalk. Fallow dockyard and port areas in the neighborhood are to become modern residential and shopping areas.

Fig. 2

Track tunneling of the noise-reduced XL 300 – clearly visible at the bottom of the photo taken before installation: U-shape of the track tunneling and the drainpipe towards bottom right.

A4

Steel Construction 14 (2021), No. 1

00_STCO_0121_Buch.indb 4

Architects Dissing+Weitling from Copenhagen won the architectural competition in 2013 with their design of a lift bridge.

The main bridge featuring a length of 48 meters can be uplifted by 28 meters along four white pylons. Long ramp constructions lead to the bridge, partly equipped with two roadway levels. The ramps feature different cross sections, they provide up to five car traffic lanes, two streetcar tracks, four bikeways, two pedestrian ways and scenic view platforms. The total length of the bridge including access bridges is 460 m.

Complex requirements for the expansion joints Ten expansion joints bridge the gaps between the various bridge and ramp sections. They have been and will be built in by MAU-

Fig. 3

Track tunneling of the noise-reduced XL 400 on the jobsite in Gothenburg: in the center the fitting pieces between which the track will be placed.

03.02.21 11:15

PRODUCTS & PROJECTS

(© MAURER)

ADVERT

Photo: MAURER

Fig. 5

Fig. 4

Installation of the noise-reduced XL400 on the new Hisingsbron in Gothenburg.

RER until 2021: from the one-profile XL1 up to the four-profile XL 400. The longest one has a length of 43 m. Because of the innercity urban utilization goals, all expansion joints have been designed noise-reduced by means of welded-on rhomboid elements. An important issue besides noise reduction was watertightness – also in places where the streetcar tracks intersect the girder sections.

And it goes without saying that the expansion joints must perform the required movements under optimum control.

Initially, finger joints were planned, with which, however, watertightness could not be achieved. Construction engineer Holger Redecker, head of the subsidiary in Lünen and in charge for Northern Europe, explains: “We were involved in the planning right from the start, thus enabling us to present an optimum solution. We have used the principle of noise-reduced modular expansion joints as a construction basis and adapted it to the requirements for the Hisingsbron.”

U-shaped streetcar track tunneling What finally came out was an expansion joint system with “track tunneling”. In places where the normally straight profiles would be intersected by the streetcar track, the profiles provide a ­U-shaped tunnel for the tracks. Usually, such track tunnels are built angularshaped. However, rounded shapes ensure better watertightness and can be cleared out more easily during cleaning.

The U-shaped tunneling is an elegant solution for the streetcar tracks – however, the Hisingsbron must be safely usable anywhere for all road users. To bridge the gap between the tracks and the U-tunnel margins, fitting pieces were screwed in, which can be dismantled for cleaning purposes.

The expansion joint lifted into position with the lift bridge in the background. On the left: the former, higher bridge.

In order to prevent water accumulation at the deepest spot of the U-tunnel, a drainpipe is welded on at the end of each tunnel that discharges the water into the sewer system. The connection of the drainage to the structure required intensive coordination with all other crafts and is an example for the complexity of these expansion joints.

Shortness of space for joist boxes The uniform distances between the individual steel profiles (central beam, steel edge profile) of an expansion joint are ensured by means of control springs that are installed in so-called joist boxes. However, due to the track tunneling the joist boxes cannot be placed arbitrarily. Sufficient height is only available in places where no track is installed above. Normally, six joist boxes would suffice for the streetcar line with a width of a good 8 m. However, since the maximum possible distances could not be fully exploited due to track tunneling, ten joist boxes each control the distances between the profiles.

Strong focus on noise reduction Considering the urban character of the new Hisingsbron and the planned residential development nearby, noise reduction was an important issue. MAURER was able to contribute its decades of experience in this field. A system with welded-on rhomboid elements is used. They are not only particularly efficient in terms of noise reduction, in addition, the special welding process is extremely durable and thus safe and sustainable.

The bridge was initially planned to be completed by 2021, the 400-year anniversary of the city of Gothenburg. However, the corona pandemic caused delays, for instance since qualified technicians were not allowed to travel to Sweden without a quarantine time. Therefore, the first roadway expansion joints were installed in June, additional joints are to be installed by 2021.

Watertightness and drainage Specially designed jaw edge profiles ensure watertightness. They were heat-bended to a U-shape and installed underneath the streetcar tracks.

00_STCO_0121_Buch.indb 5

www.maurer.eu

Steel Construction 14 (2021), No. 1 A5

03.02.21 11:15

PRODUCTS & PROJECTS

ADVERT

Mammoet swiftly sets pedestrian bridge in Colorado Mammoet’s team was recently contracted by Kiewit Infrastructure to move and install a pedestrian bridge weighing approximately 550t (1.1 million lbs.) as part of a revitalization effort in downtown Colorado Springs, Colorado. The installation of the bridge required crossing eleven railroad tracks, so precise planning was crucial to ensure minimal outage time and the Bridge move was in fact completed ahead of schedule with minimal disruption to railroad.

Mammoet has extensive experience in setting bridges around the globe, including three bridges for Fig. 1 The 76mbridge was set into place using Mega Jacks and SPMTs The Villages community in Florida and the recent installation of a pedestrian bridge at Seattle-Tacoma airport. All of this expertirailroad authorities gave an eight-hour work window to comse was needed to meet the project’s strict time requirements: plete the entire installation of the bridge.

Eight 500-ton Mega Jacks

(© Dan Oldfield/City of Colorado Springs)

Prior to Mammoet’s arrival, the 76m (250 ft.) prefabricated bridge was assembled, welded together, and given a concrete walking surface.

Once on site, Mammoet crews used eight ­500-ton Mega Jacks to hoist the bridge close to seven meters (22 ft.) in the air to allow for the installation of SPMTs for transport.

Installationrequired crossing eleven railroad tracksand was completed using steel and wooden mats

Fig. 3

The bridge was set on SPMTs and driven to itsfinal installation location

A6

Steel Construction 14 (2021), No. 1

00_STCO_0121_Buch.indb 6

Ahead of schedule Once the transportation phase of the project was completed, the bridge was jacked-down into its final installation location. Mammoet’s team had risen to the challenge, and was able to cross the tracks, install the bridge and remove the 64 axle-lines of SPMT in just under five hours, allowing the railway to begin operations again ahead of schedule.

(© Mammoet)

Fig. 2

The use of these jacks allowed the team to keep the bridge’s center of gravity low while traversing the tracks. A combination of wooden and steel mats was used to safely cross the railroad tracks and ensure there was no load bearing directly on them - as this could potentially damage the highly trafficked tracks.

The bridge is slated to open in early 2021 and will connect the America the Beautiful Park to southwest downtown, which includes the U.S. Olympic and Paralympic Museum and Hall of Fame as its centerpiece. www.mammoet.com

03.02.21 11:15

Editorial

The convenient equilibrium between the development and updating of a normative code, research and ­engineering practice.

We have repeatedly faced the debate about the convenience of structural normative codes.

Personally, I have always advocated for normative documents that regulate the design and execution of our structures by stating the relevant principles and application rules. Nevertheless, it is evident that the determination of the contents of such documents, and the scope thereof, Prof. Enrique Mirambell must be carried out thoroughly in order to eliminate, or at least minimize, the risks associated with drafting standards that do not meet the requirements for a document of this type. It is not correct to regard these normative codes as documents including cutting-edge methods and formulations from the latest research advances. Instead, the contents of these codes should refer exclusively to principles and rules of application widely understood by the practising community as consolidated knowledge; principles and rules that have already been duly warranted both theoretically and through practical application. It is also inappropriate to conceive normative codes as textbooks containing theoretical, analytical, numerical and experimental developments that support teaching or learning activities; this is not their purpose. From this point of view, it is important to recognize the significance of the content of structural codes, since one of their main goals is to provide practising engineers with appropriate guidelines to design structures through the establishment of principles and application rules. Therefore, practising engineers must be familiar with this type of document and should be in possession of the appropriate knowledge and skills to implement these guidelines correctly in practical design situations. So for designers, the application rules prescribed in structural codes should be unambiguous and easy to use.

Moreover, the existence of regulatory codes should never be a barrier to the development of new products and new design methods in the construction sector; this is one of the reasons why structural codes are regularly updated.

The EN Eurocodes form a series of European Standards that provide a common approach for the design of buildings, civil engineering works and construction products. The Eurocodes are expected to contribute to the establishment and functioning of the internal European market for construction products and engineering services by eliminating the disparities that hinder their free circulation within the community.

Currently, the Eurocodes are in an updating and maintenance phase. Although the aim of updating the codes is to address new methods, new materials, new regulatory requirements and new needs, in general, maintenance tasks comprise all activities connected with the updating of the Eurocodes in the light of practical experience gained though use: correcting errors, preparing technical amendments regarding safety issues, technical and editorial improvements, eliminating inconsistencies and misleading statements, and resolving questions of interpretation resulting from feedback.

At the present time, Eurocode 3 (EN 1993), covering steel structures, is immersed in this updating process. The excellent work being undertaken by the Chair of Subcommittee 3 (TC250/SC3), the Working Groups for the different parts of Eurocode 3 and the Project Teams allows us to be optimistic and confident that the new normative documents emerging from this revision will comply with all the requirements for a code with the characteristics outlined above. This will be achieved by reaching the convenient equilibrium between what is sought (the revision of a normative code), the research (the background work behind any process requiring consolidated knowledge) and the applicability of the code to engineering practice.

Prof. Enrique Mirambell School of Civil Engineering Department of Civil and Environmental Engineering Universitat Politècnica de Catalunya, UPC

© 2021 Ernst & Sohn Verlag für Architektur und technische Wissenschaften GmbH & Co. KG, Berlin · Steel Construction 14 (2021), No. 1

00_STCO_0121_Buch.indb 1

1

03.02.21 11:15

DOI: 10.1002/stco.202000048

Ulrike Kuhlmann, Christina Schmidt-Rasche, Fabian Jörg, Vahid Pourostad, Jennifer Spiegler, Mathias Euler

ARTICLE

Update on the revision of Eurocode 3 Evolution by improvement and harmonization Extended keynote paper of Eurosteel 2021 This paper provides an overview of recent work regarding the revision of Eurocode 3 on the European level. Selected scientific and technical issues are described and there is a summary of the activities executed within European Standardization Committee CEN/TC250/SC3 “Design of Steel Structures” chaired by Prof.

Dr.-Ing. Ulrike Kuhlmann. This includes the description of current normative developments for the 2nd Generation of Eurocodes, which aim at evolution through improvements and harmonization of the existing codes. In addition, a technical review of selected rules is given for several issues, which support the code revision and reflect well the recent tendencies in steel structures.

Keywords Mandate M/515; working group; project team; lateral torsional buckling; flow chart; final draft; calibration of partial factors; plate buckling; fillet welds; fatigue; detail tables, standardization

to Design of concrete (EC2), steel (EC3) and composite steel and concrete structures (EC4) up to Design of aluminium structures (EC9), in altogether 58 parts – were published prior to June 2007. Their development was a great achievement and represented the culmination of over 30 years’ collaborative effort. Their impact has been considerable, affecting the day-to-day work of around 500,000 professional engineers across Europe [1], [2]. In the Eurocodes, in order to allow countries to decide on their own safety levels and to give national geographic and climatic data, so-called Nationally Determined Parameters (NDPs) are available within the framework of National Annexes. As a consequence, the full implementation of the Eurocodes in the European countries was not completed until 2010 and even later, after all national codes had been withdrawn and replaced by the Eurocodes and associated National Annexes.

1 Introduction The next generation of Eurocode 3, i.e. EN 1993 “Design of Steel Structures”, is being developed at the moment as part of the whole development of the 2nd Generation of Eurocodes. Therefore, first of all there is an overview of the integration of Eurocode 3 into the whole system of Eurocodes, the organizational structure and its further development in general within the framework of Mandate M/515.

More specifically, the normative development of Euro­ code 3 is addressed in the following. How the main aims of the revision of the Eurocodes are reached with respect to ease of use, harmonization and technical improvements will be demonstrated for a number of examples.

Additionally, a technical review of selected rules is given for several new developments in some of the basic parts of Eurocode 3. This results in new chances for steel structures and the further development of the design of steel structures.

It is widely recognized that long-term confidence in the codes requires the Eurocodes to evolve in an appropriate manner. The accepted work programme [2] for the 2nd Generation of Eurocodes focuses on ensuring that the standards remain fully up to date by including new methods, new materials and new regulatory and market requirements.

Furthermore, the revision work focuses on further harmonization and a major effort to improve the ease of use of the suite of standards for practitioners. In order to show opportunities for participation in the development of these new design rules, the normative process is explained in the following. Fig. 1 gives an overview of the recent organizational structure of CEN/TC250, responsible for all Eurocodes.

2.2

Scope of Mandate M/515

All 10 of the existing Structural Eurocodes – from Basis of structural design (EC0) and Actions on structures (EC1)

The further evolution of the Eurocodes is realized within the scope of Mandate M/515 [1], which was agreed in December 2012 between the European Commission and CEN. Among the aims of the mandate are the extension of the Eurocode rules in terms of new materials, products and construction methods, improving the practical use for day-to-day calculations and achieving better harmonization by reducing the number of NDPs.

This is an open access article under the terms of the Creative Commons AttributionNonCommercial-NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made.

The mandate started in 2015 and will end in 2022. The first revised version of the Eurocodes should be available in 2021/2022. However, due to the necessary formal procedures including, for example, CEN Enquiry and CEN

2

Procedure for the development of the 2nd Generation of Eurocodes

2.1 General

2

© 2021 The Authors. Published by Ernst & Sohn Verlag für Architektur und technische Wissenschaften GmbH & Co. KG, Berlin. Steel Construction 14 (2021), No. 1

00_STCO_0121_Buch.indb 2

03.02.21 11:15

Fig. 1

ARTICLE

U. Kuhlmann, C. Schmidt-Rasche, F. Jörg, V. Pourostad, J. Spiegler, M. Euler: Update on the revision of Eurocode 3

Organizational structure of CEN/TC250 [3]

formal vote, publication may not be completed until 2024.

In general, the revision can be subdivided into the following two activities: – General revisions and maintenance of the Eurocodes: This is the usual procedure for a code revision according to CEN, which is launched in the form of a call for “systematic reviews” to the NSBs (National Standardization Bodies, e.g. DIN, AFNOR, BSI, AENOR, etc.). The evaluation and implementation of the suggestions and comments is then carried out by the CEN TC250 Subcommittees and Working Groups.

– Technical enhancements of the Eurocodes within the scope of Mandate M/515: Further development takes place simultaneously with the general revision within Mandate M/515. Similarly to the transfer of the ENV versions into the EN versions, the realization is conducted by Project Teams (PTs) that consist of a maximum of five or six members.

The CEN/TC 250 work programme has been split into four overlapping phases. This has been done to enable the interdependencies between activities to be managed effectively and to ensure that the work is undertaken as efficiently as possible.

Phase 1 includes those parts of the work programme upon which other activities are primarily dependent for

00_STCO_0121_Buch.indb 3

reasons of overall coordination, technical scope or because they are essential for achieving the target dates for delivery of the next generation of Eurocodes. Phase 1 of the mandate started in 2015 and ended in 2018 after three years. Phase 2 started in 2017, also for a term of three years. Phase 3 and Phase 4 started in 2018 [3].

There are two main aims of the mandate work concerning the improvement and harmonization of existing rules: reduction in the number of NDPs and enhancing ease of use.

Tab. 1 gives a summary of the number of NDPs in the current Eurocodes relative to the number of parts in each ­Eurocode and number of pages. In fact, Eurocode 3 has one of the the highest number of NDPs in comparison to the other Eurocodes, but also the highest number of pages.

The especially large variety of different steel structures has led to altogether 20 parts, which cover an exceptionally large scope of different steel structures including buildings, bridges, silos, tanks, masts and towers. The very uneven distribution also shows that for some Eurocodes, NDPs form a means to overcome different views on technical items. In these cases document N1250 [2] recommends a procedure to overcome these differences in order to achieve better harmonization.

As a second point “enhancing ease of use” has been defined as a major aim of the development of the 2nd Generation of Eurocodes. A number of principles and related priorities have been defined after long discussions in Steel Construction 14 (2021), No. 1 3

03.02.21 11:15

U. Kuhlmann, C. Schmidt-Rasche, F. Jörg, V. Pourostad, J. Spiegler, M. Euler: Update on the revision of Eurocode 3 Tab. 1 Analysis of NDPs in the current ECs [2]

Eurocode

No. of parts

No. of pages

No. of NDPs

EN 1990

1+Annex A2

90+30

54

EN 1991

10

770

292

EN 1992

4

450

176

EN 1993

20

1250

236

EN 1994

3

330

42

EN 1995

3

225

21

EN 1996

4

300

31

EN 1997

2

340

42

EN 1998

6

600

103

EN 1999

5

500

58

TC250, the committee responsible for Structural Eurocodes in CEN. The “General principles” especially demonstrate the common understanding of “ease of use”. This has also been summarized by: 1. improving the clarity, 2. simplifying routes through the Eurocodes, 3. limiting, where possible, the inclusion of alternative application rules, and 4. avoiding or removing rules of little practical use in design.

3

Eurocode 3 – Development of 2nd Generation

3.1 Overview Of all the Eurocodes (EN 1990 to EN 1999), Eurocode 3 (EN 1993) with its 20 parts and approximately 1250 pages is the most extensive one. Fig. 2 gives an overview of the structure of the existing Eurocode 3 showing the “application parts”, such as Part 2 for bridges or Part 3 for towers, masts and chimneys, which refer to the “general parts” within Part 1 and to the relevant parts in Eurocode 1 for Actions.

TC250/SC3, the relevant subcommittee for Eurocode 3 on steel structures, agreed on a defined approach for the revision and harmonization of Eurocode 3 as early as April 2010: The questions relating to the revision and harmonization of Eurocode 3 are solved in cooperation between CEN/ TC250/SC3 and the Working Groups of SC3 and are elaborated in the form of proposals for amendments.

These proposals are then sent to CEN for approval and for final inclusion in the Eurocode. The Working Groups consist of members who are specialists in particular areas of expertise and who are nominated by the National Standardization Bodies (NSBs) of the different member countries. The SC3 submitted its last technical review in the form of amendments to the existing parts of Eurocode 4

Fig. 2

Structure and overview of existing Eurocode 3

3 during the meeting of the CEN/TC250 in Delft in November 2013. In the future, technical modifications will be carried out within the scope of the mandate work. The only exception is for amendments relevant to safety, which can still be submitted and decided on for the existing versions of Eurocode 3.

Meanwhile, SC3 has also agreed to follow the same procedure for the development of and agreement on technical changes that are to be implemented in the new version of Eurocode 3. These agreed “amendments” were put into the “basket” for the time when the Project Team started its work and were then implemented in the new versions. Further, to advise and follow the work of the Project Teams, the Working Groups of SC3 play an important role.

Tab. 2 gives an overview of the future structure of Eurocode 3 and the different SC3 Working Groups responsible for the different parts.

In general, the structure of Eurocode 3 has been kept the same compared with the existing code, see Fig. 2. Small modifications to the structure of Eurocode 3 are explained in the following.

As an example of following the principle of “Enhanced ease of use by avoiding or removing rules of little practical use in design”, TC250/SC3 decided to withdraw Eurocode 3: Design of steel structures – Part 4-3: Pipelines.

There are many other EN standards for pipelines for a specific common purpose, whereas Part 4-3 seemed to have been used very little. However, when drafting the decision for withdrawal, it turned out that there was an

Steel Construction 14 (2021), No. 1

00_STCO_0121_Buch.indb 4

03.02.21 11:15

Tab. 2 Structure of future Eurocode 3 on steel structures and SC3 Working Groups responsible

Part of Eurocode 3

Type Topic

Working group

General rules and rules for ­buildings

WG1

EN 1993-1-2

Structural fire design

WG2

EN 1993-1-3

Supplementary rules for cold-­ WG3 formed members

EN 1993-1-4

Stainless steels

WG4

EN 1993-1-5

Plated structural elements

WG5

EN 1993-1-6

Strength and stability of shell structures

WG6

EN 1993-1-7

Plate assemblies with elements WG7 under transverse loads Design of joints

WG8

Fatigue

WG9

EN 1993-1-10

Material toughness and through-thickness properties

WG10

EN 1993-1-11

Design of structures with tensi- WG11 on components

EN 1993-1-12

Additional rules for steel grades WG12 up to S960

EN 1993-1-13

Steel beams with large web openings

WG20

EN 1993-1-14

Design assisted by finite element analysis

WG22*

EN 1993-2

Steel bridges

WG13

EN 1993-3

Towers, masts and chimneys

WG14

Silos

WG15

Tanks

WG16

Piling

WG18

Crane supporting structures

WG19

Design of sandwich panels

WG21

EN 1993-1-9

EN 1993-4-1 EN 1993-4-2 EN1993-5 EN 1993-6 EN 1993-7

Application parts

EN 1993-1-8

General parts

EN 1993-1-1

rent draft has mainly been developed within the mandate as a special task and by a Project Team of CEN/TC250/ SC4 responsible for composite steel concrete structures.

A final document has been developed further in TC250/ SC3/WG20 and is now being distributed in SC3 for decision [4].

ARTICLE

U. Kuhlmann, C. Schmidt-Rasche, F. Jörg, V. Pourostad, J. Spiegler, M. Euler: Update on the revision of Eurocode 3

In order to improve clarity by simplifying routes through the Eurocodes, the current content of EN 1993-1-12 on additional rules for the extension of EN 1993 up to steel grades S700 has been distributed to the relevant other parts of Eurocode 3 (since the application of these parts has been extended to high-strength steels – HSS), meaning that the current version of EN 1993-1-12 could be withdrawn. However, SC3 decided to develop a new EN 1993-1-12 with a different scope, namely, high-strength steels up to grade S960. This activity is not covered by the mandate given by the EU and will be finalized later when sufficient knowledge and experience is available. Regarding the general aims, this development supports the inclusion of the latest development by extending the scope to new materials, new products, new methods and new market requirements.

Furthermore, a new part EN 1993-7 on the design of sandwich panels will be added to complement the mandated work. This again is a sign of the inclusion of the latest developments by extending the scope to new materials, new products, new methods and new market requirements.

As a very innovative development, a new part EN 1993-114 on design assisted by finite elements, which anticipates the wider use of finite element analysis in the design of steel structures in the future, will be added. Here, first of all an Ad-Hoc-Group (AHG FE) consisting of members of various SC3 Working Groups developed a first draft, transferring, among other things, rules from other parts of Eurocode 3, such as Annex C of EN 1993-1-5, to this general part. Meanwhile, a dedicated Working Group WG22 is dealing with this subject.

* prior to AHG FE

3.2 Austrian National Annex to Part 4-3 covering the design of penstocks (high-pressure water pipelines used in hydroelectric applications) which seemed to be in use.

Therefore, it was decided to develop a Technical Specification based on the Austrian National Annex to allow the use of these design methods. A preliminary work item for the development of TS 1993-4-301: Eurocode 3 – Penstocks has been accepted.

Further, the current parts EN 1993-3-1 (masts and towers) and EN 1993-3-2 (chimneys) have been merged into one EN 1993-3, thus avoiding overlaps in the content of the current two parts.

EN 1993-1-13 is a new part on steel beams with large web openings (e.g. cellular and castellated beams). The cur

00_STCO_0121_Buch.indb 5

Development of EC3 within the framework of Mandate M/515

For the work within the mandate, the 20 parts of Eurocode 3 have been subdivided into 13 tasks. For these 13 tasks, the technical contents were developed in the form of so-called Project Proposals in collaboration with the convenors of the respective Working Groups and coordinated within SC3 [1].

As EN 1993-1-1 and EN 1993-1-8 are the basic parts of Eurocode 3, it is necessary to harmonize a number of issues with other parts, so these two parts were dealt with right at the beginning in Phase 1. Furthermore, four SC3 tasks, most of them dealing with stability, were assigned to the early part of Phase 2 of the mandate. The material-specific parts of Eurocode 3, e.g. EN 1993-1-4 Steel Construction 14 (2021), No. 1 5

03.02.21 11:15

U. Kuhlmann, C. Schmidt-Rasche, F. Jörg, V. Pourostad, J. Spiegler, M. Euler: Update on the revision of Eurocode 3 Tab. 3 Tasks of Mandate M/515 concerning Eurocode 3

Task ref.

Task phase

Corresponding Part of EN 1993

Task name

SC3.1

1

EN 1993-1-1

Design of sections and members according to EN 1993-1-1

SC3.2

1

EN 1993-1-8

Joints and connections according to EN 1993-1-8

SC3.3

2

EN 1993-1-3

Cold-formed members and sheeting. Revised EN 1993-1-3

SC3.4

2

EN 1993-1-5

Stability of plated structural elements. Revised EN 1993-1-5

SC3.5

2

EN 1993-1-6, -1-7

Harmonization and extension of rules for shells and similar structures. Revised EN 1993-1-6 and EN 1993-1-7

SC3.6

2

EN 1993-1-2

Fire design of steel structures. Revised EN 1993-1-2

SC3.7

3

EN 1993-1-4

Stainless steels. Revised EN 1993-1-4

SC3.8

3

EN 1993-1-9

Steel fatigue. Revised EN 1993-1-9

SC3.9

3

EN 1993-1-10

Material and fracture. Revised EN 1993-1-10

SC3.10

4

EN 1993-2, -1-11

Steel bridges and tension components. Revised EN 1993-2 and EN 1993-1-11

SC3.11

4

EN 1993-3

Consolidation and rationalization of EN 1993-3

SC3.12

4

EN 1993-4

Harmonization and extension of rules for storage structures. Revised EN 1993-4-1 and EN 1993-4-2

SC3.13

4

EN 1993-5, -6

Evolution of EN 1993-5 Piling and EN 1993-6 Crane supporting structures

and EN 1993-1-10, are assigned to Phase 3, whereas Phase 4 of the mandate primarily covers the application parts, e.g. EN 1993-2 on steel bridges. The assignment of the tasks to the phases is shown in Tab. 3.

drafts for the CEN Enquiry by DIN as the SC3 Secretariat responsible. Finally, in the SC3 meeting in October 2019, there was an official decision in SC3 that prEN 1993-1-1 should be proceeded to the CEN Enquiry, whereas for prEN 1993-1-8 this decision was taken in April 2020.

3.3

The planned timetable for all parts and phases of Eurocode 3 is given in Tab. 4.

Status of development of Eurocode 3 and its parts

As part of the Project Teams’ contract within the mandate, they have to deliver a “Final Draft” at a certain point in time, which is sent out to the NSBs for the so-called Informal Enquiry. National Mirror groups comment on these drafts, the comments are collected and the Project Teams consider them and, if possible, modify the drafts accordingly. At the end of the Project Team contract, these modified drafts are handed over to the relevant subcommittee in order to solve any unanswered questions and find a harmonized view on them, and also to prepare the text for the official CEN Enquiry. SC3 decided at a relatively early stage on a “publication plan” for the various drafts in order to schedule this procedure (SC3 Decision 20/2018).

Further, it was decided to attain official Technical Approval of SC3 based on the single drafts before starting the final editing and correction. So, for example, prEN 19931-1:2020 gained Technical Approval in October 2018, which allowed the other Project Teams in the following phases to rely on the content of this basic general part of Eurocode 3 for the development of their own parts.

This enables optimal harmonization to be achieved within the different parts of Eurocode 3. Reference groups of four to seven experts were established in WG1 and WG8 to give advice or seek confirmation by the Working Groups if needed for the necessary editorial changes or small technical corrections during the preparation of the 6

CEN/TC250 has fixed, for all Eurocodes, possible dates for the start of the formal CEN Enquiry and necessary preparatory times beforehand. This preparatory time includes phases for the checking of the draft by the TC250 secretariat, for the editing by CCMC (the CEN institution responsible) and for the translation into German and French by DIN and AFNOR. During the CEN Enquiry of about 16 weeks, the draft is distributed in all member countries and official agreement and comments are requested by all NSBs. Following that, the draft is returned to the subcommittee for review of the comments and possible modifications of the text if necessary. This modified draft then runs through the same procedure as for the formal CEN Enquiry in order that it can be sent out to the member countries for the Formal Vote, which lasts about eight weeks. The agreement by the NSBs to the Formal Vote should not contain any technical comments, only editorial remarks. After editorial corrections, if necessary,

by CCMC and translation, the draft is sent out to the NSBs to be published in the different countries together with a National Annex.

The whole implementation procedure for new Eurocodes may seem a rather protracted process, but the various possibilities for commenting and correcting represent an important chance to influence the content.

Steel Construction 14 (2021), No. 1

00_STCO_0121_Buch.indb 6

03.02.21 11:15

Tab. 4 Planned timetable for development of EC3

Task phase

Corresponding part of EN 1993

Start of informal enquiry

Draft available for SC3

SC3 decision Start of formal Technical ­Approval of SC3 for start of CEN CEN Enquiry Enquiry

1

EN 1993-1-1

December 2017

June 2018

October 2018

October 2019

September 2020

1

EN 1993-1-8

December 2017

June 2018

March 2019

March 2020

March 2021

2

EN 1993-1-3

October 2019

June 2020

October 2020

March 2021

March 2022

2

EN 1993-1-5

October 2019

June 2020

October 2020

March 2021

March 2022

2

EN 1993-1-6, -1-7

October 2019

June 2020

March 2021

March 2022

March 2023

2

EN 1993-1-2

October 2019

June 2020

October 2020

March 2021

March 2022

3

EN 1993-1-4

October 2020

June 2021

October 2021

March 2022

March 2023

3

EN 1993-1-9

October 2020

June 2021

October 2021

March 2022

March 2023

3

EN 1993-1-10

October 2020

June 2021

October 2021

March 2022

March 2023

4

EN 1993-2, -1-11

March 2021

February 2022

October 2022

March 2023

March 2024

4

EN 1993-3

March 2021

February 2022

October 2022

March 2023

March 2024

4

EN 1993-4

March 2021

February 2022

October 2022

March 2023

March 2024

4

EN 1993-5, -6

March 2021

February 2022

October 2022

March 2023

March 2024

4

Technical review of selected code rules

4.1

EN 1993-1-1

To enhance ease of use, the focus of the revision of EN 1993-1-1 was on simplifying and clarifying the stability rules, unifying the rules between general and application parts and reducing the number of rules (for lateral torsional buckling in particular). In the current code there are seven different options for verifying lateral torsional buckling, which were reduced to just three in the new version prEN 1993-1-1:2020 [5], again following the principle of “limiting the inclusion of alternative application rules”: standard method (see 8.3.2.1 and 8.3.3), simplified method (8.3.2.4) and general method (8.3.4). One decisive step here was the replacement of the two different sets of lateral torsional buckling curves for the “general case” (EN 19931-1, cl. 6.3.2.2), which usually concerns sections without pronounced torsional properties, and the “special case” (EN 1993-1-1, cl. 6.3.2.3), mainly for rolled and similar welded cross-sections, by a new approach that has been developed by Taras [6] and can also be followed in more detail in [7]. In addition, of the, currently, two methods for beam-column design, only “Method 2”, as given in Annex B of the current EN 1993-1-1, has been retained and integrated into the main text. The content of “Method 1”, as given in Annex A, has been transferred to a Technical Specification, “CEN/TS 1993-1-101 Eurocode 3 – Design of steel structures – Part 1-101: Alternative interaction method for members in bending and compression” [8], to allow for the continued use of these rules in the countries that have traditionally chosen to use Annex A exclusively.

For the sake of clarity, the new section 7 “Structural analysis” in the draft prEN 1993-1-1:2020 [5] has been

00_STCO_0121_Buch.indb 7

ARTICLE

U. Kuhlmann, C. Schmidt-Rasche, F. Jörg, V. Pourostad, J. Spiegler, M. Euler: Update on the revision of Eurocode 3

restructured compared with the current section 5 on structural analysis, while largely retaining the same content. The new section 7 links the calculation of the internal forces with the verification at the ultimate limit state.

This section deals with the conditions under which second-order effects have to be considered for the calculation of internal forces, whether and which imperfections have to be assumed and if a stability member check may be performed. Similar guidance is currently given in EN 1993-1-1, cl. 5.2.2. However, it has been shown that these rules often led to misunderstandings in practice and are interpreted very differently depending on traditional approaches. Within the revision, these different views and traditions were harmonized and put together in a flow chart, see Fig. 3, which clearly connects the type of structural analysis and the choice of imperfections with the way of verifying the member resistance at the ultimate limit state.

Depending on the extent and type of consideration of structural deformations according to second-order theory and imperfections, three approaches are possible: – Complete calculation of internal forces according to second-order theory including the consideration of global and local imperfections (method M5).

– Partial consideration of second-order effects and imperfections in the global analysis and partial consideration through individual member stability checks (methods M2 to M4).

– For simple systems, through individual stability checks of equivalent members, considering buckling lengths corresponding to the overall structural behaviour (alternative method EM).

Steel Construction 14 (2021), No. 1 7

03.02.21 11:15

U. Kuhlmann, C. Schmidt-Rasche, F. Jörg, V. Pourostad, J. Spiegler, M. Euler: Update on the revision of Eurocode 3

Fig. 3

Methods of structural analysis applicable to ultimate limit state design checks (Fig. 7.3 in prEN 1993-1-1:2020 [5])

The choice of method is clearly based on certain decisions concerning the need to consider second-order effects. The list of methods starts with the simplest case, i.e. a first-order analysis suffices (method M0) and ends up with a calculation based on second-order theory also taking into account torsional effects and global and local imperfections, in-plane and out-of-plane.

During the development and validation of new design rules for the next generation of EN 1993-1-1, it became apparent that a standardized procedure was needed to assess the reliability level of these rules. The basis for this procedure is formed by uniform sets for the statistical distribution of the mechanical and geometric properties of European steel products. The new, informative Annex E explicitly states the most important assumptions and procedures on which the determination of the recommended values of the partial safety factors γM relies. As a new feature introduced to contribute to clarity and transparency, a new, informative Annex E is given in prEN 1993-11:2020 which contains the basic assumptions for the cali8

bration of partial factors. The recommended partial factors for the design of buildings as given for ultimate limit states in para. 8.1 [5] are based on calibrations assuming certain distributions for material strength as well as geometry. As stated, the intended users of this annex are mainly the National Standardization Bodies, which are responsible for structural reliability in general and thus for the setting of the various Nationally Determined Parameters (NDPs) in Eurocode 3, for which the values of the partial factors γM represent one of the most prominent examples.

New tables in Annex E contain the relevant statistical parameters for the most important mechanical (Tab. E.1) and geometric properties (Tab. E.2). They are derived from a database that is representative for the materials and products currently available on the European market which satisfy the relevant European product standards.

More background is also given in [7]. These values are not intended for direct use by designers but should aid National Mirror Committees when agreeing or disagreeing

Steel Construction 14 (2021), No. 1

00_STCO_0121_Buch.indb 8

03.02.21 11:15

on the partial factors. They also form a basis for discussions with steel producers regarding identifying possibilities for ways in which appropriate product qualities may be guaranteed. This kind of information might finally be part of a Technical Specification or a code supplied by steel producers.

4.2

EN 1993-1-5

Fig. 4

Definition of dimensions of a non-rectangular panel

To improve the existing rules in EN 1993-1-5 [9] on plate buckling in view of the next generation of prEN 1993-15:2020 for EN 1993-1-5 “Plated structural elements”, socalled amendments were developed at a very early stage.

These amendments were decided on by SC3 and then put in the “basket” up to the time when the Project Team started its work and could implement these improved rules in the new draft without major discussions. More than 25 new amendments (2011–2020) have been developed for implementation in the new draft; they include:

ingly used in the design of new bridges due to architectural and/or structural advantages, are explained in the following. The application of the effective width method according to the existing EN 1993-1-5 [9] is limited to rectangular panels with parallel flanges. According to the existing rules [9], the effective width method is only valid for an angle Φ < 10°, see Fig. 4. However, the design approach for non-rectangular panels is not clearly explained.

– – – – – – –

Based on numerical and experimental investigations, design rules for non-rectangular buckling were proposed in [12] to [15]. This proposal has been integrated into the new version prEN 1993-1-5:2020 [10]. In doing so, the validity of the effective width method has been increased to 17.5° and more clarity for the design of non-rectangular panels is provided.

Shear resistance of longitudinal stiffeners Resistance of longitudinal stiffeners to direct stresses Resistance of girders subjected to patch loading Rules for corrugated webs F-M-V interaction Biaxial compression Consideration of torsional stiffness of closed-section stiffeners – Flange-induced buckling Aiming for “ease of use” and more clarity, again the structure in the new version prEN 1993-1-5:2020 [10] has largely been improved; for example: – the former Annex C (informative) “Finite Element Methods of Analysis (FEM)” mainly moved to EN 19931-14, – the former Annex D (informative) “Plate girders with corrugated webs” integrated into the main text, and – the former Annex E (normative) “Alternative methods for determining effective cross-sections” integrated into the main text.

According to the new rules, the buckling verifications of non-rectangular panels should be carried out based on the action effects at each end of the panel: – at a distance 0.5b1 from the end of the panel with smaller width (b1) (section 1, see Fig. 5), – and a distance of 0.5b2 if

0.4 a if

In particular, the former Section 10 “Reduced stress method” was completely reorganized and improved to achieve better clarity so that in future this method, which had been used mainly in Germany and Austria, may also be accessible for others. Again, a flow chart developed within the framework of a German BASt project [11] helps to explain the different steps in the verification.

MEd,2 Mf,Rk,2 MEd,2 Mf,Rk,2

≥

<

MEd,3 Mf,Rk,3 MEd,3 Mf,Rk,3

from the panel end with larger width (b2) (section 2 or 3, see Fig. 5)

where: MEd,2 and MEd,3 are the bending moments acting at the section at a distance 0.5b2 and 0.4a respectively from the panel end with larger width (see cross-sections 2 and 3 in Fig. 5).

One big achievement resulting from discussions with each other and with the relevant Working Group 5 was that the Project Team was able to reduce the number of NDPs from the current 15 to just four in the final draft [10].

Mf,Rk,2 and Mf,Rk,3 are the characteristic plastic moments of resistance of the cross-section consisting of the effective area of the flanges only at a distance of 0.5b2 and 0.4a respectively from the panel end with larger width.

As an example of improvements to design rules, the new rules for non-rectangular steel plates, which are increas-

The comparison of the bending moments at sections 2 and 3 with the flange bending resistances allows the user

00_STCO_0121_Buch.indb 9

ARTICLE

U. Kuhlmann, C. Schmidt-Rasche, F. Jörg, V. Pourostad, J. Spiegler, M. Euler: Update on the revision of Eurocode 3

Steel Construction 14 (2021), No. 1 9

03.02.21 11:15

U. Kuhlmann, C. Schmidt-Rasche, F. Jörg, V. Pourostad, J. Spiegler, M. Euler: Update on the revision of Eurocode 3

Fig. 5

Position of sections for verification of non-rectangular panels

to check which is the critical verification beforehand: the one for section 2 or for section 3. According to the rules for the design of non-rectangular panels, the critical section should be used for all verifications such as bending (M), shear (V) and M-V interaction. The gross cross-section should also be checked at both ends of the panel.

Owing to the geometry of the inclined compression flange, the shear force may be modified. The force distribution due to the inclined compression flange is shown in Fig. 6, where Nx,f is the horizontal force resulting from the bending moment. The inclined flange force NFlange is composed of this horizontal force Nx,f and the vertical force Vz,f acting on the web. The modified shear force in the web VMod is calculated by Eqs. (1) and (2). The shear (V) and M-V interaction should be verified using the modified shear force VMod. (1) Vz,f = N x,f ⋅ tan(Φ ) VMod = VEd − Vz,f (2) One of the main questions in the design of girders with a variable cross-section concerns the buckling coefficients.

Differently from rectangular panels, which always have higher stresses on the support side, this is not always the case for non-rectangular panels. In some cases, under bending, there are higher stresses on the side with lower web depth. The larger side is often more relevant for the buckling analysis than the smaller side; however, the stresses are usually smaller. That is why both sides of the panel need to be checked, see Fig. 5.

non-rectangular (real) shape of the panel. The panel may be modelled by applying the real stresses at the end of the panel as acting stresses. If the exact determination of the critical stress is not possible with LBA, the critical stresses or buckling coefficients can be calculated on the safe side by assuming the panel is rectangular but with the larger width. The corresponding stresses at the end of the panel are applied on both sides of panels. The critical load factors acr determined may be used in buckling verifications for all sections. Since, in the case of a non-rectangular panel, the stresses vary at each section, a unique slenderness should be determined for each section using the critical load factors acr of the panel. Finally, using the unique slenderness of each section, the reduction factors or the effective cross-section should be determined and buckling verifications carried out.

4.3

EN 1993-1-8

The use of high-strength steels (HSS) represents one of the main developments for modern steel structures. However, for the particular situation of joining HSS elements, the present design rules, e.g. in EN 1993-1-8 [16], for the design of joints are in many cases inadequate because the recent rules were developed for standard steels and then transferred to high-strength steels. This is obvious from Fig. 7, where the current weld strength is shown in grey.

The weld strength of S460 is in fact lower than for S355.

Several research projects [17], [18], which included a large number of tests on fillet welds, resulted in the development of a realistic and coherent design model for determining the load-carrying capacity of welded connections for HSS; meanwhile, this has been accepted for the future version of Eurocode 3 by TC250/SC3.

New correlation factors βw have been defined for S460 and S690 steels to achieve a constant level of safety. This results in an improved loadbearing capacity for S460, but a reduced loadbearing capacity for S690, see Fig. 7. Correlation factors for S420 to S700 have been chosen accordingly.

In addition, based on [19], a new formula has been introduced which differentiates between fu,PM (parent materi-

The critical stresses or buckling coefficients may be calculated using linear buckling analysis (LBA) considering the

Fig. 6

Influence of inclined compression flange

10

Steel Construction 14 (2021), No. 1

00_STCO_0121_Buch.indb 10

Fig. 7

Comparison of weld strength now (grey) and in the future (blue)

03.02.21 11:15

al) and fu,FM (filler material), see Eq. (3). Using this formula it is possible to cover mismatch effects, i.e. higher (overmatching) or lower (undermatching) strength of the filler metal compared with the parent metal. Undermatching may have advantages regarding ductility, weldability and quality.

(

)

0.25 ⋅ fu,PM + 0.75 ⋅ fu,FM (3) σ ⊥2 + 3 ⋅ τ ⊥2 + τ 2 ≤ and β w,mod ⋅ γ M2

σ⊥ ≤

2

Filler metal strength class

42

46

69

89

Ultimate strength of filler metal fu,FM [N/mm2]

500

530

770

940

Correlation factor βw,mod [–]

0.89

0.85

1.09

1.19

For filler metals different to those given in Tab. 5, the correlation factor should be chosen conservatively according to the given values.

0.9 ⋅ fu,PM

γ M2

where: fu,PM nominal ultimate tensile strength of the parent metal, which is of lower strength grade fu,FM nominal ultimate tensile strength of the filler metal, see Tab. 5 and according to EN ISO 2560, EN ISO 14341, EN ISO 16834, EN ISO 17632 and EN 18276 bw,modt modified correlation factor that depends on the filler metal strength, see Tab. 5 From the results it can be seen that the strength of fillet welds is dominated by the filler metal (75 %). This design model may be used for fillet-welded connections in steel grades equal to or greater than S460 and with different parent and filler metal strengths. Additionally, this method can be used for partial penetration butt welds.

Another important change of prEN 1993-1-8:2020 is the restructuring of the existing chapter 5 “Analysis, classification and modelling” and chapter 6 “Structural joints connecting H or I sections” into new chapters 7 “Structural analysis” and 8 “Structural joints connecting H or I sections” which clearly describe only the procedure and the basic principles, see [20], whereas the details of the components and application rules for specific joints – such as moment-resisting beam-to-column joints and splices connecting H or I sections, simple connections and column bases – are given in new, normative annexes: – Annex A (normative) “Structural properties of basic components” – Annex B (normative) “Application rules for momentresisting beam-to-column joints and splices” – Annex C (normative) “Application rules for simple connections” – Annex D (normative) “Application rules for column bases”

4.4

Tab. 5 Ultimate strength of filler metals fu,FM and modified correlation f­ actor βw,mod according to Tab. 6.2 [20]

ARTICLE

U. Kuhlmann, C. Schmidt-Rasche, F. Jörg, V. Pourostad, J. Spiegler, M. Euler: Update on the revision of Eurocode 3

EN 1993-1-9

Without changing the basic rules of the existing part EN 1993-1-9 Fatigue [24], but with the aim of clarification, the future prEN 1993-1-9:2020 [21] will distinguish between fatigue design concepts representing the design philosophies (such as damage-tolerant and safe-life concepts) and the different fatigue design methods that are

00_STCO_0121_Buch.indb 11

the tools used for the design concepts. One major change is the introduction of specific recommendations for other stress-based design methods, in particular the hot-spot stress method and the notch stress method, besides the well-known nominal stress method. To distinguish between the different stress methods, a far more precise stress definition has been added to clarify how hot-spot and notch stresses should be computed. As before, the main document of prEN 1993-1-9:2020 focuses on the fatigue verification based on the nominal stress method because of its great practical importance. Specific annexes are additionally provided for the hot-spot stress and the notch stress methods.

Another important change in comparison to the existing EN 1993-1-9 [24] concerns the detail tables, which are the heart of the nominal stress method and have been completely revised (Fig. 8). Up to now the tables represented the corresponding details in descending order of detail category. Therefore, all details in a table are more or less mixed. In contrast, for user-friendliness, the revised tables in the new draft [21] treat the details in sequence. The user gets better illustrations and an improved and clarified compilation of different execution qualities and associated detail categories for each detail.

As before, the tables start with a “detail category” column on the left followed by a “constructional detail” column with illustrations. In comparison to the current standard, the illustrations have essentially been improved. For many constructional details, the illustrations have been scaled up so that the point of potential fatigue failure is clear and to support the literal characterization in the “description” column. Moreover, a “symbol” column has been added for welded details to indicate the appropriate weld quality compatible with the detail category considered. The introduction of weld symbols facilitates the communication between design office and workshop and is far better for preventing misunderstandings.

In general, the use of the detail tables requires a weld quality level B according to EN ISO 5817 [22], an accredited assignment of personnel and an extent of non-destructive testing (NDT) as specified by EN 1090-2 [23].

Consequently, the last column in each table only contains supplementary requirements beyond the specifications of EN 1090-2.

Steel Construction 14 (2021), No. 1 11

03.02.21 11:15

U. Kuhlmann, C. Schmidt-Rasche, F. Jörg, V. Pourostad, J. Spiegler, M. Euler: Update on the revision of Eurocode 3

Fig. 8

Extract from revised detail table for built-up members [21]

5

Summary and conclusions

This paper has shown the normative evolution for steel structures within the framework of the development of the 2nd Generation of Eurocodes. In doing so, the revision process within the scope of Mandate M/515 of the Eurocodes in general and the 20 parts of EN 1993 in particular is described, which aims at improvements to and harmonization of the existing codes. Besides the general revision and maintenance of the Eurocodes, some selected technical issues are explained. They also represent some of the new developments based on recent research,

which present new chances for steel structures and the further development of the design of steel structures, e.g. the use of high-strength steels. Thanks to diverse international research activities and the implementation of research results in the new harmonized code version, the competitiveness of steel structures will be increased.

Acknowledgements Open access funding enabled and organized by Projekt DEAL.

References This paper follows partially the paper “Development of Eurocode 3 and research contributions” by Kuhlmann, Ulrike; Schmidt-Rasche, Christina; Spiegler, Jennifer; Jörg, Fabian; Pourostad, Vahid; and Euler, Mathias for the VII ACHE CONGRESSO [25].

[1] CEN TC250 N993 (2013) Response to Mandate M/515 (Mandate for amending existing Eurocodes and extending the scope of structural Eurocodes) “Towards a second Generation of EN Eurocodes”, Brussels, May 2013.

[2] CEN TC250 N1250 (2020) Policy guidelines and procedures (version 9.1), Brussels, Mar 2020.

[3] CEN TC250 N2511 CEN TC250 (2020) Presentation, by the Chair, virtual meeting, 14-15 May 2020.

[4] CEN TC250 SC3 N3150 (2020) Final document of EN 1993-1-13, Feb 2020.

[5] prEN 1993-1-1:2020 (2020) Eurocode 3: Design of steel structures – Part 1-1: General rules and rules for buildings, draft as proceeded to CEN Enquiry, Sept 2020, CEN TC250 SC3 N3159.

[6] Taras, A. (2011) Contribution to the Development of Consistent Stability Design Rules for Steel Members. Institute for Steel Structures and Shell Structures, Graz University of Technology, vol. 16.

12

[7] Knobloch, M.; Bureau, A.; Kuhlmann, U.; da Silva, L.S.; Snijder, H. H.; Taras, A.; Bours, A.-L.; Jörg, F. (2020) Structural Member Stability Verification in the New Part 1-1 of the Second Generation of Eurocode 3 – Part 1: Evolution of Eurocodes, background of partial factors, cross-section classification and structural analysis in: Steel Construction 13, No. 2, pp. 98–113, https://doi.org/10.1002/ stco.202000016; Part 2: Member buckling design rules and further innovations in: Steel Construction 13, No. 3, pp.

298–222, https://doi.org/10.1002/stco.202000027.

[8] CEN/TS 1993-1-101 (2019) Eurocode 3 – Design of steel structures – Part 1-101: Alternative interaction method for members in bending and compression, 4th draft, 18 Mar 2019, CEN/TC250/SC3 N2808.

[9] EN 1993-1-5 (2006) Eurocode 3: Design of steel structures – Part 1-5: Plated structural elements, EN 1993-1-5:2006 + AC:2009.

[10] prEN1993-1-5 (2020) Design of steel structures – Part 1-5: Plated structural elements. Final document, Apr 2020, CEN/TC 250/SC3 N 3135.

[11] Kuhlmann, U.; Schmidt-Rasche, C.; Frickel, J.; Pourostad, V. (2017) Untersuchungen zum Beulnachweis nach DIN

Steel Construction 14 (2021), No. 1

00_STCO_0121_Buch.indb 12

03.02.21 11:15

EN 1993-1-5. Berichte der Bundesanstalt für Straßenwesen, Brücken- und Ingenieurbau Heft B 140, BASt, FE.89.0313/2015, available at https://bast.opus.hbz-nrw. de/opus45-bast/frontdoor/deliver/index/docId/1816/file/ B140_Internet_PDF.pdf.

[12] Pourostad, V.; Kuhlmann, U. (2020) Report on investigation of buckling behaviour of non-rectangular panels, background document, May 2020, CEN/TC 250/SC 3/WG 5 N 197.

[13] Simões da Silva, L.; Kuhlmann, U.; Može, P.; Pedro, J. O.; Hendy, C. et al. (2019) Optimal and aesthetic design of curved steel bridges (OUTBURST), Research Fund for Coal and Steel, grant agreement No. RFCS-2015-709782.

[14] Pourostad, V.; Kuhlmann, U. (2018) Experimental investigations on girders with non-rectangular panels in: Proc. of 8th Intl. Conf. on Thin-Walled Structures, ICTWS 2018, Lisbon.

[15] Pourostad, V.; Kuhlmann, U. (2019) Experimental and numerical investigations of unstiffened steel girders with nonrectangular panels subjected to bending and shear in: Proc. of Intl. Colloq. on Stability & Ductility of Steel Structures, SDSS 2019, Prague.

[16] EN 1993-1-8 (2005) Eurocode 3: Design of steel structures – Part 1-8: Design of joints, EN 1993-1-8:2005 + AC:2009.

[17] Kuhlmann, U.; Vormwald, M.; Werner, F.; Köhler, G. et al.

(2008) Forschungsvorhaben P 652: Wirtschaftliche Schweiß­ verbindungen höherfester Baustähle. FOSTA Forschungsvereinigung Stahlanwendung e.V., Düsseldorf: Verlag und Vertriebsgesellschaft.

[18] Kuhlmann, U. Rasche, C. (2014) Forschungsvorhaben P 812: Tragfähigkeit von Kehlnahtverbindungen höherfester Baustähle S690 im Stahlbau. FOSTA Forschungsvereinigung Stahlanwendung e.V., Düsseldorf: Verlag und Vertriebsgesellschaft.

[19] Rasche, C. (2012) Zur Bestimmung der Tragfähigkeit von Kehlnahtverbindungen höherfester Baustähle. Dissertation No. 2012-1, Institute of Structural Design, University of Stuttgart.

[20] prEN 1993-1-8:2020 (2020) Eurocode 3: Design of steel structures – Part 1-8: Design of joints, draft after including comments, 8 Apr 2020, CEN TC250 SC3 N3098.

[21] prEN 1993-1-9:2019 (2020) Eurocode 3: Design of steel structures – Part 1.9: Fatigue, 2nd draft, Apr 2020, CEN/TC 250/SC3 N 2850.

[22] EN ISO 5817:2014-06 (2014) Welding – Fusion-welded joints in steel, nickel, titanium and their alloys (beam welding excluded) – Quality levels for imperfections (ISO 5817:2014).

[23] EN 1090-2:2018-09 (2018) Execution of steel structures and aluminium structures – Part 2: Technical requirements for steel structures.

[24] EN 1993-1-9 (2005) Eurocode 3: Design of steel structures – Part 1-9: Fatigue, EN 1993-1-9:2005 + AC:2009.

[25] Kuhlmann U.; Schmidt-Rasche C.; Spiegler J.; Jörg F.; Pourostad V.; Euler M. (2020) Development of Eurocode 3 and research contributions, VII Congreso de la Asociación Española de Ingeniería Estructural ACHE, 24-26 Jun 2020.

Authors Prof. Dr.-Ing. Ulrike Kuhlmann sekretariat@ke.uni-stuttgart.de Institute of Structural Design University of Stuttgart Pfaffenwaldring 7 70569 Stuttgart, Germany

Jennifer Spiegler, MSc jennifer.spiegler@ke.uni-stuttgart.de Institute of Structural Design University of Stuttgart Pfaffenwaldring 7 70569 Stuttgart, Germany

Dr.-Ing. Christina Schmidt-Rasche (corresponding author) christina.schmidt-rasche@ke.uni-stuttgart.de Institute of Structural Design University of Stuttgart Pfaffenwaldring 7 70569 Stuttgart, Germany

Dr.-Ing. Mathias Euler mathias.euler@ke.uni-stuttgart.de Institute of Structural Design University of Stuttgart Pfaffenwaldring 7 70569 Stuttgart, Germany

ARTICLE

U. Kuhlmann, C. Schmidt-Rasche, F. Jörg, V. Pourostad, J. Spiegler, M. Euler: Update on the revision of Eurocode 3

Fabian Jörg, MSc fabian.joerg@ke.uni-stuttgart.de Institute of Structural Design University of Stuttgart Pfaffenwaldring 7 70569 Stuttgart, Germany Vahid Pourostad, MSc vahid.pourostad@ke.uni-stuttgart.de Institute of Structural Design University of Stuttgart Pfaffenwaldring 7 70569 Stuttgart, Germany

00_STCO_0121_Buch.indb 13

How to Cite this Paper Kuhlmann, U.; Schmidt-Rasche, C.; Jörg, F.; Pourostad, V.; Spiegler, J.; Euler, M. (2021) Update on the revision of Eurocode 3. Steel Construction 14, No. 1, pp. 2–13. https://doi.org/10.1002/stco.202000048 This paper has been peer reviewed. Submitted: 13. August 2020; accepted: 14. December 2020.

Steel Construction 14 (2021), No. 1 13

03.02.21 11:15

DOI: 10.1002/stco.202000061

Gioacchino Sarcina, Francesco Poltronieri, Marco Raccagni, Siro Dal Zotto, Lorenzo Sartori, Vito Cardella, Andrea Morbin

REPORT

Genoa San Giorgio Bridge The realization of an iconic artifact A bridge that slowly crosses Polcevera Valley, step by step, in silence, almost asking for permission; a bridge that will be like a ship, a big white vessel moored in the valley; a bridge that can’t be banal in its simplicity; a bridge made by Italian excellences who, through an intense activity of coordination, planning and the work of expert professionals, had to carry out the work as soon as possible. It is through the words of its designer, architect and senator for life Renzo Piano, that we want to introduce the new Genova San Giorgio Bridge. The steel contractor’s approach to the realization of the work is summed up in the words of the CEO Giuseppe Bono: “The bridge must be an expression and a symbol of the country all over the world.

All this is Fincantieri, what we have done so far and what we will do. Fincantieri represents something unique in our country, with introduction of its unparalleled integration model.” The steel contractor has made the replacement of former Morandi bridge possible only two years after the tragic events of 14 August 2018, bringing the road system of the Autostrada dei Fiori motorway back to normal.

Keywords Genoa; Fincantieri; steel bridge; compositive structure

1 Introduction The temporary association of companies Fincantieri Infrastructure, Webuild and Italferr based on the design idea of the architect Renzo Piano, was awarded the contract for all the construction works necessary for the structural and functional restoration of the Polcevera Viaduct in Genoa through a direct assignment received by the Extraordinary Commissioner for Reconstruction, Marco Bucci with an assignment dated 18 December 2018.

Fincantieri Infrastructure therefore received the assignment from the newly established consortium company called PERGENOVA to carry out the detail design and the fabrication, assembly and installation of the metal structural works.

Rina Consulting was appointed to manage the construction and therefore control of product quality, management and risks related to the execution of the works, while architectural management was entrusted to Architect Renzo Piano. The work, for the purpose of use and interference with the railway areas, was carried out according to the following specifications: 14

– ANAS: Special tender specifications – Technical Rules for the execution of the contract – Part 2 IT. PRL.05.17 Rev. 1.0 – Major works of art bridges and viaducts – RFI in the area of relevance and as required: General technical tender specifications for civil works Part II – Section 6 RFI DTC YES PS SP IFS 001 C – Concrete and steel conglomerate works

2

From the idea to the design

The new bridge was built on a route substantially parallel to that of the former Morandi Bridge, connecting the Coronata tunnel on the western side with the A10-A7 junction on the eastern side. The access ramp to the bridge for vehicles transiting on the A7 coming from Milan is part of the new structure.

The work has a development on the main axis of 1,067 m, consisting of 14 spans of 50 m, 1 of 41 m, 1 of 26 m and 3 central spans crossing the Polcevera river at 100 m. The access ramp consists of 4 continuous bays for 110 m overall. The main deck is supported by 18 piers, all with the same elliptical section with a major axis of 9.50 m and a minor axis of 4.00 m. The ramp section is supported by 3 piers, always elliptical in shape but with axes of 5.00 and 2.50 m. In operation, the deck has an overall transverse dimension of 32.00 m and a cross-sectional height of 4.82 m.

The section of the deck and its layout, in particular due to the presence of a curve on the west side, required the use of a torsion-rigid section. In particular, the latter was obtained with 2 longitudinal beams with a middle m distance of 7.00 m, a curved calendared bottom (with a typical thickness of 20 mm, which increases to 40 mm for the 100 m spans) and a slab at the top made of collaborative concrete. The bottom is not limited to being a mere formal aspect of the structure but is configured as a load-bearing element, fulfilling the function of the lower floor of the caisson section. During assembly, in the absence of the slab, the bearing function of closing the upper floor of the box was performed by a floor bracing with coupled angles. The continuity of the central core is ensured by full penetration welded joints.

The span segments had typical lengths of 13.60 m and 15.20 m, the pier segments had a standard length of 6.00 m and had two sturdy projecting metal structures at

© 2021 Ernst & Sohn Verlag für Architektur und technische Wissenschaften GmbH & Co. KG, Berlin. Steel Construction 14 (2021), No. 1

00_STCO_0121_Buch.indb 14

03.02.21 11:15

ments extended for fusion welding of metallic materials” and EN 1090-1:2009+A1:2011 EXC4 for the Execution of CE certified steel structures. The basic products were purchased from leading companies in the sector in accordance with the relevant European CE certified product standards. The materials used were mainly UNI EN 10025-2: 2005 S355J2+N steel sheets, S355K2+N and UNI EN 10025-3: 2005 S460N, S460NL steel.

Fig. 1

The architectural shape of the ship’s keel commissioned by the architect Renzo Piano

the bottom intrados that connect the deck beam to the supports.

Two appendages descend alongside the beams of the pier with the dual function of seismic retention and a point of contrast to the jacks necessary for lifting the deck in maintenance operations during the operation of the work.

REPORT

G. Sarcina, F. Poltronieri, M. Raccagni, S. Dal Zotto, L. Sartori, V. Cardella, A. Morbin: Genoa San Giorgio Bridge – The realization of an iconic artifact

While the existing works were demolished on the construction site in Genoa and the work areas freed up for subsequent construction of the sub-foundation and foundation works, the main structures of the metal deck were produced at the steel contractors production sites. The production has been developed in accordance with the usual strategy of the Fincantieri Group, which carries out production on the basis of the deadlines necessary for the realization of the individual elements, amplifying the work by priority and objective, in order to complete the works necessary for the construction of an entire span in in the shortest possible time. The “Fast Track” methodology inevitably conditioned the site operations, and it

The parts external to the central core, the „side panels“, create triangular elements made up of pairs of tie-strut elements with a constant distance between the middle points of 4.55 m; the lower struts are welded together by a 10 mm thick bottom plate which completes the architectural shape of the deck keel. The side panels are connected to the central core by bolted joints (Fig. 1).

The section is completed by the “panels”, made up of a continuous metal sheet, acting as the edge beam of the slab, and of the protruding metal sheets that support the walkways, passageways for systems, windows and photovoltaic panels. The panels are continuous along the length of the deck, with full penetration welded joints, and connected to the crankcases by bolted joints.

It is therefore evident that the deck structure with a mixed steel-concrete section has two different resistance mechanisms, namely the torsion-rigid one for the „central core“ and the tie-strut mechanism for the „side panels“.

3

From design to production

The structural engineer decided that the main structures of the work were to be built in accordance with the necessary specifications according to the maximum level of execution class EXC4, according to product standard UNI EN 1090-2:2011 referred to in the Technical Standards for Construction in 2018.

All the production sites involved have, in addition to UNI EN ISO 9001: 2015 “Quality management system” certification, also UNI EN ISO 3834 Part 2 “Quality require

00_STCO_0121_Buch.indb 15

Fig. 2

General view of deck from Ponente side

Steel Construction 14 (2021), No. 1 15

03.02.21 11:15

G. Sarcina, F. Poltronieri, M. Raccagni, S. Dal Zotto, L. Sartori, V. Cardella, A. Morbin: Genoa San Giorgio Bridge – The realization of an iconic artifact

was also necessary for the reinforced concrete works to be carried out simultaneously in such a way as to give enough anticipation to the laying of the deck (Fig. 2).

The Fincantieri Group used the sites in Valeggio sul Mincio (VR), Castellammare di Stabia (NA) and Sestri Ponente (GE) to produce the Genoa Bridge for the construction of the metal structures the deck was made of.

Only through the preliminary analysis of the potential and skills of the individual sites was it possible to focus the objective of each plant and maximise productivity.

The dressing elements of the macro elements and all the upper structures such as longitudinal beams, transverse elements and profiles were made, welded and checked at the production site Valeggio S/M equipped with automatic welding systems such as the T-Master, with tandem configuration, and manipulators with one and two opposing welding heads; the technologies used maximize the repeatability of the welding process, ensuring its quality.

The macro elements that form the bottom of the deck were made in the shipyards of Castellammare di Stabia and Sestri Ponente with a bottom plate welded in a single solution through the use of automatic „Panel Line“ welding equipment, to then be structured with longitudinal beams and transverse stiffeners. In an equally strategic way, the pier elements, structural elements of considerable constructive complexity due to the presence of heavy stresses and welds of particular difficulty and size, were separated from in-line production. The decision to make the 18 pier segments as complete structural elements was fundamental to optimise construction times. After the completion of the geometric control activities and the execution of Non-Destructive Testing (NDT), the structural elements were painted with a highly durable C5 VH paint cycle in a very aggressive environment in accordance with UNI EN ISO 12994 – 2 and a decisive finishing colour wanted by the Architectural Management of RAL Design 220 80 05 with a surface gloss of 30 %. The macro elements made at the production sites of Castellammare di Stabia and Sestri Ponente were transported by barges across the Tyrrhenian Sea to the pier near the mouth of the Polcevera river (Fig. 3); once disembarked and positioned on particular multi-axle and high lift trailers, they

were transported to the construction site with big overnight transport vehicles.

The maximum width of 10 m of the macro elements was analysed in the design phase to allow the particular transport method, performed with a few spare centimetres in relation to the passage areas.

The entire metal deck has a total weight of about 17,500 tons of which about 77 % was processed at Valeggio S/M. Part of this material was delivered directly to the shipyard in Val Polcevera while 30 % was transported to the Naval production sites where the structural elements were welded to the metal sheets of the previously prepared keeled bottom. The construction and shipment of the 262 macro segments based on the management programme prepared and monitored daily was essential for respecting the project’s challenging implementation deadlines.

4

Assembly and monitoring of the works

The spans were assembled starting from the calendered bottoms placed on provisional works on which each segment was progressively based with the diaphragms, main beams, side panels and, finally, the panels. The upper main beams were welded to the lower beams along with the bottom of the segment by means of longitudinal corner bead welding. The segments were subsequently welded together at full penetration before being moved to be raised.

The joint preparation, preheating and welding control activities were supervised by the welding coordinators and checked upon completion of the same in accordance with the inspection plan with visual, magnetic and ultrasound methods. All the personnel used for welding activities on the ground and at height were in possession of licenses issued by the accredited third party Accredia.

The upper transverse elements and the diaphragms were assembled by means of bolted joints using HRC bolts.

This particular bolt allows the reduction of the tightening control times required by the standards to ensure the successful application of the tightening torque.

All the movements of the segments and the macro elements of the spans were carried out with SPMT (Self Propelled Modular Transport) trolleys, in modules with 4 or 6 axes that can be assembled according to transport needs. The system offered great versatility in displacements and made it possible to move from the smallest macro-segments, weighing about ten tons, up to 100 m fully assembled spans of 1,800 tons (Fig. 4).

Fig. 3 Loading on barge of the macro blocks in Castellammare di Stabia (Naples)

16

The construction site faced extremely adverse environmental conditions, with almost 100 days of hydrogeological weather alert from September 2019 to June 2020 with whole days of intense rain or strong wind. In addition to this, in a paroxysm of complications, the Covid19 pandemic exploded in Italy. The first strong containment countermeasures that almost stopped the nation were es-

Steel Construction 14 (2021), No. 1

00_STCO_0121_Buch.indb 16

03.02.21 11:15

Fig. 4

Movement with SPMT trolleys of a 100 m span

tablished at the most important moment of the assembly, when the lifting above the river was in progress and the lifting of the span above the railway was imminent. To the professional tension due to the importance of the phase to be overcome, the physical fatigue of the previous months, the stress caused by the incessant media attention given to the construction site, human concern for health reasons was added. It was at this moment that all the people involved gave the greatest sign of strength and cohesion, capable of reshaping the way of working to ensure common safety, managing to maintain the same very high pace that had been sustained up to that moment, with the collective goal of completing the work.

5

REPORT

G. Sarcina, F. Poltronieri, M. Raccagni, S. Dal Zotto, L. Sartori, V. Cardella, A. Morbin: Genoa San Giorgio Bridge – The realization of an iconic artifact

Fig. 6

50m spam ready for tandem lifting

Fig. 7

Tandem lifting of the span between piers 3 and 4

Movement of the decks

The lifting was divided into two types, with cranes and lifts with strand jacks. A pair of tandem cranes were used for the 50 m spans. A single heavy-duty crane was used for the shoulder lifts (SA-P1, P1-P2, P17-P18 and P18-SB) and ramp lifts. Strand jacks were used for the 100 m spans and the two key lifts of P2-P3 and P11-P12 (Fig. 5).

The tandem lift technique involved the assembly of the segments in two main configurations.

Fig. 5

Four spam assembled in Levante site

00_STCO_0121_Buch.indb 17

Steel Construction 14 (2021), No. 1 17

03.02.21 11:15

G. Sarcina, F. Poltronieri, M. Raccagni, S. Dal Zotto, L. Sartori, V. Cardella, A. Morbin: Genoa San Giorgio Bridge – The realization of an iconic artifact

Fig. 8

Movement with SPMT of a 100 m span and lifting equipment with strand jack

– The two initial lifts (P5-P6 and P14-P15) were made with a macro element consisting of the two central pier segments and the central part of the span, to create a self-supporting structure; – The subsequent lifts were carried out by moving the entire span and the subsequent stack of stone, relying on the previous element moved using special brackets.

The spans thus configured raised in tandem had a weight of between 400 and 600 tons (Fig. 6).

The lifting sub-contractors made a total of five crawler cranes available, all operating simultaneously between February and March 2020: – Two Terex-Demag CC2800, maximum capacity 600 tons – A Terex-Demag CC3800, maximum capacity 650 tons – Two Terex-Demag CC6800, maximum capacity 1250 tons The tandem lifting took place by coupling a CC6800 with a CC2800 (or alternatively the CC3800) configured with 78 m arms, choosing the gripping points to maximise the efficiency of crane capacity (Fig. 7).

It was not possible to intervene as described above for the end areas of the deck, due to the impossibility of creating spaces close to the shoulders, due to the interference of persistent motorway traffic and the complex orography with steep slopes. For these sections, the single lift technique was adopted with large-capacity cranes and the use of temporary towers to break down the spans into subsegments of a weight suitable for the crane’s capacity compatible with the large outreaches required.

Fig. 9

Lifting phase of the 100m span between piers 8 and 9

considerable weights involved for lifting and to resolve interference with the substructures, it was necessary to resort to the lifting technique using strand jacks (Fig. 8).

For each lift, four pairs of cable recovery jacks were used connected to the deck to be lifted with dedicated eyebolts and stiffeners.

To raise the spans from 100 m from the side of the deck at high altitude, a system of lifting beams and eyebolts made it possible to balance the lifting actions, while on the opposite side this function was performed by a block of ballasts. Each jack has a limit capacity of 1,400 tons and a cable recovery stroke of 450 mm, which in practice translates into a deck lifting speed of about 7 m/h (Fig. 9).

Before lifting each of these spans, it was necessary to position the stack segment on the next alignment to install the strand jacks and the adjustment system for inserting the spans. Structures were installed under the segments of P9, P10 and P11 which made it possible, thanks to pairs of jacks positioned along the three main axes, to move the pier segment in order to precisely align the spans at a height. The raised spans, with an overall length of 94 m, were inserted into an opening just 5 cm wider. This precision was achieved thanks to the cutting of the ends of the spans on the ground according to the angle of the edges of the piers, surveyed topographically, aided by a regulation

For these lifts (SA-P1, P1-P2, P17-P18 and P18-SB) and the ramp lifts, a single CC6800 was used with a change of boom configuration at 114 m for the west side, 102 m for the eastern side and 78 m for the ramp.

The 100 m spans and the two 50 m closing spans (P2-P3 and P11-P12) were instead completely assembled on the ground, including pre-slabs, slow reinforcement of the slab and system elements inside the deck, arriving at a maximum total weight of approximately 1,800 tons. Due to the 18

Fig. 10 Taking charge of the span with SPMT trolleys in the Polcevera riverbed

Steel Construction 14 (2021), No. 1

00_STCO_0121_Buch.indb 18

03.02.21 11:15

1.50 m for movement onto the Polcevera and about 3.00 m for positioning above the railway, requiring the use of special temporary structures to be interposed between the deck and SPMT trolleys (Figs. 10, 11).

REPORT

G. Sarcina, F. Poltronieri, M. Raccagni, S. Dal Zotto, L. Sartori, V. Cardella, A. Morbin: Genoa San Giorgio Bridge – The realization of an iconic artifact

The first lift was carried out on 1 October 2019 in the Ponente part of the construction site, while the first lift in the Levante part of the construction site was realised on 15 December 2019.

Fig. 11 100 m span above the Polcevera river ready for lifting

On 28 April 2020, with the key closure of the P11-P12 span, the two banks of the Val Polcevera were reunited.

The lifting operations were definitively concluded with the positioning of the last span of the ramp on 29 May 2020, just 333 days after the arrival of the first structural element on site (Fig. 12).

6

Final activities and testing

Once the deck at height was completed, with the assembly of the side panels, panels, the installation of the slabs and the mild reinforcement, before casting the slab, the weighing of the deck and the lowering up to the design height remained to be performed.

The spans were laid on the piers 265 mm higher than the design height, to allow the weighing of the deck and the application of the design constraints, as well as to have adequate ease in the assembly of the provisional and final supports.

The final supports of the deck, double-surface pendulum isolators, could not be directly loaded during the transitional assembly phase since they were not designed for the application of movements and rotations necessary only during the spans’ laying and alignment phase.

Fig. 12 Lifting connection of the coupling structure to the bridge

system that closed the opening once the joints were correctly aligned, ensuring the millimetre tolerances necessary for making joints with full penetration at a height.

For the Polcevera and railway crossing spans it was necessary to carry out preliminary lifting due to the differences in height between the areas where the SPMTs had to move and due to the height of the obstacles. (Via 30 Giugno, Via Perlasca and the railway grounds) This lift (in other words jack-up) raised the decks with respect to the support height for the assembly by about

00_STCO_0121_Buch.indb 19

When the operations at height were finished, the deck was placed accurately on the piers, sensitive due to their slenderness to excessive decentralization that thermal variations could result in during assembly at height. For this operation, provisional elements were made which encapsulated, on each pier, two pairs of vertical jacks and a pair of horizontal jacks, resting on a sliding guide made up stainless steel-teflon which allowed the required longitudinal and vertical displacements to be obtained.

The jacks, equipped with precision pressure gauges, therefore made it possible to measure the constraint reactions and to adjust the measured value with small constraints until it corresponded to the theoretical values. At the end of the weighing, the bridge was lowered step by step to the desired height and then grouting of the supports was caried out. The structural continuity between the deck, support and pier, was therefore completed, a situation that effectively sanctioned the conclusion of the assembly of the metal deck.

Steel Construction 14 (2021), No. 1 19

03.02.21 11:15

G. Sarcina, F. Poltronieri, M. Raccagni, S. Dal Zotto, L. Sartori, V. Cardella, A. Morbin: Genoa San Giorgio Bridge – The realization of an iconic artifact

The casting of the concrete slab, laying of the road surface and dressing it with safety barriers, photovoltaic panels and protective windows, as well as the installation of robotic means for the control and cleaning of the deck, allowed the static and dynamic testing of the works to start.

For the dynamic testing, an operational modal analysis (OMA) was carried out with the aid of Tromino® tromographs synchronized to uniaxial velocimeters suitably positioned on the spans. Thanks to the measurement of the vibrations induced by natural microtremors (wind, traffic, nearby production activities) it was possible to check the correspondence of the real vibration of the structure with the theoretical vibration. A further dynamic type test to verify any horizontal displacements on the supports or piers was performed with a braking test with 8 fully loaded trucks that travelled over the deck at a speed of 50 km/h, at P9, which braked synchronously to a stop. The test did not show any appreciable displacement of the transducers positioned on the supports.

Fig. 13 General view of Ponte San Giorgio

A total of 56 5-axle trucks (tractor plus trailer) loaded up to 46 tons and 4 SPMT modules loaded to 130 tons were used for the static testing, for a total of 12 tests (4 with negative moment on Piers 4, 10, 15 and pier 3 of the ramp, 7 with positive moment on spans SPA-P1, P3-P4, P4-P5, P9-P10, P14-P15, P2-P3 of the ramp and a test on

Fig. 14 Italy on Ponte San Giorgio

20

Steel Construction 14 (2021), No. 1

00_STCO_0121_Buch.indb 20

03.02.21 11:15

the coupling between the ramp and main axis), during which 100 % of the stress test required by the design was reached. The single typical positive moment test required 24 vehicles, for a total of more than 1,000 tons, while for the negative moment test of pier 10 required 44 vehicles spread over the two adjacent spans. The SPMTs were used on the ramp spans where the reduced width of the road platform would have allowed the positioning of an insufficient number of trucks to reach the stress level to be verified. The measured lowering corresponded fully to the expected values, of about 2.00 cm deflection in the 50 m Spans and 8.00 cm for the 100 m spans.

For the testing and monitoring activities, the range of instruments used was completed by the strain gauge sensors installed on the metal carpentry in the middle of spans P3-P4 and P9-P10 and piers 4, 10 and 15 and the strain gauge bars embedded in the concrete of the slab of the above-mentioned piers and on pier 3 of the ramp. This set of sensors made it possible to verify, in real time, the evolution of the stress state of the section while the tests progressed and will continue to measure the deformations of the deck during the life-cycle of the structure, allowing constant monitoring of the structure over time in a simple and reliable manner (Figs. 13, 14).

Authors Eng. Gioacchino Sarcina (corresponding author) Gioacchino.Sarcina@fincantieri-infrastructure.it Fincantieri Infrastructure S.p.A. Via del Lavoro, 1 37067 Valeggio sul Mincio, Verona, Italy

Eng. Siro Dal Zotto Siro.DalZotto@fincantieri-infrastructure.it Fincantieri Infrastructure S.p.A. Via del Lavoro, 1 37067 Valeggio sul Mincio, Verona, Italy

7 Conclusion

REPORT

G. Sarcina, F. Poltronieri, M. Raccagni, S. Dal Zotto, L. Sartori, V. Cardella, A. Morbin: Genoa San Giorgio Bridge – The realization of an iconic artifact

An iconic project managed by leading companies in the sector that have managed to continuously supply a construction site that managed to meet the deadlines promised to the City of Genoa and above all to its citizens. A success achieved only with very detailed planning of the activities and thanks to the work and skills of people who felt as if they were an integral part of a project characterised by efficiency, safety and quality. The bridge, in addition to healing a wound in the city of Genoa, mapped out a method with which to deal with the execution of the large-scale works in Italy, Competence – Efficiency – Planning.

Project team Architect: Arch. Renzo Piano Steel structural engineer: Italferr S.p.A. Rina Consulting S.p.A. Project supervisor: Main contractor: Pergenova S.C.p.A Steel main fabricator: Fincantieri Infrastructure S.p.A. Fincantieri S.p.A. Steel sub fabricator: Lifting sub contractor: Fagioli S.p.A. Lifting sub contractor: Vernazza Autogru S.r.l.

Civil contractor: Webuild S.p.A. Vito Cardella Vito.Cardella@fincantieri-infrastructure.it Fincantieri Infrastructure S.p.A. Via del Lavoro, 1 37067 Valeggio sul Mincio, Verona, Italy Andrea Morbin Andrea.Morbin@fincantieri-infrastructure.it Fincantieri Infrastructure S.p.A. Via del Lavoro, 1 37067 Valeggio sul Mincio, Verona, Italy

Eng. Francesco Poltronieri Francesco.Poltronieri@fincantieri-infrastructure.it Fincantieri Infrastructure S.p.A. Via del Lavoro, 1 37067 Valeggio sul Mincio, Verona, Italy Eng. Marco Raccagni Marco.Raccagni@fincantieri-infrastructure.it Fincantieri Infrastructure S.p.A. Via del Lavoro, 1 37067 Valeggio sul Mincio, Verona, Italy Eng. Lorenzo Sartori Lorenzo.Sartori@fincantieri-infrastructure.it Fincantieri Infrastructure S.p.A. Via del Lavoro, 1 37067 Valeggio sul Mincio, Verona, Italy

00_STCO_0121_Buch.indb 21

How to Cite this Paper Sarcina, G.; Poltronieri, F.; Raccagni, M.; Dal Zotto, S.; Sartori, L.; Cardella, V.; Morbin, A. (2021) Genoa San Giorgio Bridge – The realization of an iconic artifact. Steel Construction 14, No. 1, pp. 14–21. https://doi.org/10.1002/stco.202000061

Steel Construction 14 (2021), No. 1 21

03.02.21 11:15

DOI: 10.1002/stco.201900037

ARTICLE

Abdulkadir Cüneyt Aydin, Aysan Ardalani, Mahyar Maali, Mahmut Kiliç

Numeric modelling of innovative semi-rigid connections under cyclic loading This paper presents the analytical results of six steel bolted T‑connection models and four steel bolted beam-to-column connection models with top and seat angles. This study was undertaken to analyse the influence of bolted T-connections instead of welded connections and the influence of angles with and without stiffeners on the behaviour of the beam-to-column connections under hysteretic loading. The aim was to compare the energy dissipation of different connections with each other.

The energy dissipation characteristics are obtained from the main characteristics of moment-rotation hysteresis curves.

This study shows that the energy dissipation decreased by about 2–29 % and 2–13 % for bolted T-connection and top-andseat-angle connection models respectively after switching from one cycle to another in five hysteretic loadings.

Keywords semi-rigid connections; T-connections; top-and-seat-angle connections; beam stiffeners; moment-rotation; energy dissipation

1 Introduction It is known that the behaviour of beam-column joints in steel frames plays a noticeable role in presenting the actual behaviour of structures [1]. Further, the moment-rotation curves, which are the visual expressions of the actual behaviour of beam-to-column connections, have been discovered in different experiments [2]. Although carrying out experimental tests is too expensive and unsuitable for everyday practice tests, the accurate behaviour of beamto-column connections can be obtained through experimental tests, and these are usually used for research purposes only [3, 4]. These experiments have been conducted since 1917, when the first experimental testing of the rigidity of steel frame joints was carried out at the University of Illinois by Wilson and Moore [5].

The four most important databases from experiments are: a. Goverdhan database [6], which was developed in 1984, containing the results of 230 tests from the USA. b. Nethercot, the first European database [7, 8], developed in 1985, which contains results from more than 70 experiments on steel connections. c. Steel connection database [9, 11]. This database collected the results of experimental tests carried out from 1936 to 1986 by Kishi and Chen [12] from all over the world. They followed the work of Goverdhan in the USA and they studied the results of 303 tests. Later, in 1995, 46 additional experimental tests on steel frame 22

joints were conducted by Abdalla and Chen [13], and their results were added to this database. d. SERICON databank [14, 15], which contains composite combinations and was developed by Arbed Recherches and Aachen University [16]. Afterwards, SERICON II was extended in 1998 by Cruz et al. [17].

By using these databases, the classification of mathematical models experimentally tested from 1958 to 1990 is limited to the following seven types of steel beam-to-column connection: i. Single web angle ii. Double web angle iii. Header plate iv. Top and seat angles v. End plate without column stiffeners vi. End plate with column stiffeners vii. T-stub However, there are many different types of beam-to-column connection that are not identified in these databases.

Owing to the important role of beam-column joints in steel structures, the use of bolted connections known as semi-rigid connections is suggested for steel frameworks in structures. The semi-rigid joints of steel structures play the most important role in the resistance, rigidity, rotation capacity and energy dissipative features. Rigid connections, which are frameworks with welded joints, are too expensive and involve difficult assembly conditions, whereas flexible connections have neither a sufficient stiffness nor the necessary resistance to static and dynamic loads [1], see Fig. 1.

The common behaviour of the beam-column connections is categorized as rigid and pinned to make frame analysis simpler. Additionally, investigations have shown that in steel structures the actual behaviour of the majority of connections is neither perfectly rigid nor perfectly hinged, so they behave as “semi-rigid” connections. Owing to the unique properties of moment-rotation relationships in semi-rigid connections, it is easy to observe the strength, stiffness and rotation capacity from the moment-rotation curve.

Many different experimental tests on beam-to-column connections of steel frameworks have been examined in recent years. The study of the different characteristics of semi-rigid connections was excluded by many research-

© 2020 Ernst & Sohn Verlag für Architektur und technische Wissenschaften GmbH & Co. KG, Berlin. Steel Construction 14 (2021), No. 1

00_STCO_0121_Buch.indb 22

03.02.21 11:15

Fig. 1

ARTICLE

A. C. Aydin, A. Ardalani, M. Maali, M. Kiliç: Numeric modelling of innovative semi-rigid connections under cyclic loading

Rotational deformation of semi-rigid connections

ers, including the work of Astaneh et al. [18], who investigated the hysteretic behaviour of steel double angle connections under severe cyclic seismic loading and examined six different connections in which angles were bolted to the column flange using A325 bolts and welded to the beam web. Azizinamini and Radziminski [19] investigated the static and cyclic behaviour of top and seat flange angles and double web angles in semi-rigid steel beam-to-column connections. Chen and Lui [20] investigated the non-linear and not easily resolvable structure for the behaviour of semi-rigid connections.

On the other hand, moment-rotation curves are necessary for presenting the actual behaviour of connections.

Further, the transformation of moment from beam to column is achieved through a moment connection such as a flush end-plate connection and stiffened or unstiffened extended end-plate connections [21]. Shi et al. [22], by carrying out experimental tests on and a theoretical analysis of stiffened extended end-plate connections, were able to ascertain the moment-rotation behaviour of these connections. Actually, they were able to control local buckling and increase shear capacity in a beam web by attaching stiffeners generally to the beam’s web or flanges. Although there has been no investigation of the use of a flat stiffener that fitted onto the angles in beam-to-column joints either in Eurocode 3 or in the literature [23], Shi et al. [22] were able to identify an adequate moment of inertia to control deformations of planes. Maali et al. [24] investigated the influence of angles and beams with stiffeners on the behaviour of beamto-column connections. The results were obtained from experimental tests on 20 full-scale specimens of steel bolted connections with top and seat angles and beam stiffeners under static loading. As a result, by increasing the thickness of the stiffener beam and the length L of the top-and-seat-angle connection, the maximum bending moment, the bending moment capacity and the stiffness increased. However, the maximum bending moment, the bending moment capacity and the stiffness were reduced by increasing the thickness of the stiffener angles. In addition, by increasing the thickness of the stiffener beam and stiffener angles, the energy dissipation also increased [25–37].

The aim of the present work is to analyse the behaviour of two types of semi-rigid beam-to-column connections

00_STCO_0121_Buch.indb 23

under hysteretic loadings, which included an investigation of the behaviour of bolted T-connections, the influence of the use of stiffeners and the change of length L of top-and-seat-angle connections by using the ANSYS Workbench program. In bolted T-connections, the handtightened full-threaded M10 and M14 grade 8.8 bolts were tested for all six models. In top-and-seat-angle connections, two different angle lengths and three different stiffener thicknesses were considered, and these connections also used the hand-tightened full-threaded M8 grade 8.8 bolts. The moment-rotation curves were obtained to identify the properties of the connections analysed, such as rotation capacity, maximum moment and energy dissipation.

2

Semi-rigid connections

The common behaviour of the beam-column connections is categorized as rigid and hinged to make frame analysis simpler. Furthermore, the relevant literature has shown that the majors of the connections are as “semi-rigid” connections, and the moment-rotation behavior is a proposed way to observe strength, stiffness and rotation capacity, etc.

3

Description of the models

This article presents the results of two groups of beam-tocolumn connections. The first group contains six fullscale models of steel bolted connections in the form of bolted T-connections, labelled as B240-T300-2-14, B240T300-1-14, B240-T270-2-14, B240-T240-1-14, B160T140-2-10 and B160-T200-1-10 (B = beam section, T = column section, the ordinal number of rows of bolts in the beam web and the diameter of bolts respectively). As a second group, four models were chosen for beam-tocolumn connections with top and seat angles, which are labelled similarly as L91-tp6-BS5 (1), L91-tp6-BS5 (2), L82-tp8, and L82-tp10. The first and second groups of 10 models were created and tested for hysteretic loading, numerically. As a result of simulations, the hysteretic loading, the loading times is decided to get lasted after five cycles. The details of the two types of model are shown in Fig. 2 and Fig. 3.

Steel Construction 14 (2021), No. 1 23

03.02.21 11:15

A. C. Aydin, A. Ardalani, M. Maali, M. Kiliç: Numeric modelling of innovative semi-rigid connections under cyclic loading

Fig. 2

Two types of FE model and mesh pattern for bolted T-connections

3.1

Mechanical properties of the models

The steel grade considered for the beam and column sections was ST37. The length chosen for the beam and column was 1 500 mm. Hand-tightened full-threaded grade 8.8 bolts were selected because of the rupture that occurs first in the bolts. The material properties were considered as bilinear isotropic with yield strength values fy = 250, 275 and 640 MPa for all the beams and angles, columns and bolts respectively. Young’s modulus E was assumed to be 210 GPa, Poisson’s ratio 0.3.

3.2

Method of modelling connections

A three-dimensional finite element model for bolted Tconnections and top-and-seat-angle connections which accounts for non-linear material and geometry was developed using the finite element method and ANSYS Workbench software. All the analysis was done as transient analysis. As a result of a preliminary analysis, five cycles of loading were decided on for all 10 models. Further, “Auto Mesh” was selected as the type of meshing for all models. In fact, a bigger mesh in beam and column and smaller mesh in section parts was defined to shorten the analysis time.

3.2.1 Bolted T-connections The connection of the beam and column sections with one and two rows of web bolts was modelled. Handtightened full-threaded M14 and M10 grade 8.8 bolts were considered for all types of model in all analyses.

The influence of the beam stiffeners, angle stiffeners and lengths L of top-and-seat-angle connections on the behaviour of moment-rotation curves of models has been evaluated [22, 33–38]. So, in this study the use of beam and angle stiffeners and their influence on the behaviour of connections was considered for all types of model.

4

Analysis of models

The ground parts of the column were defined as a fixed support. The displacement of the web of the beam was fixed in the X direction. The surface contact between beam and column was defined as frictionless. The surface contact between bolts and nuts was defined as bonded. The surface contact between the holes in beams and columns and the bolts was defined as no separation.

The models were analysed under hysteretic loading. The force was applied as a transient between 1.1 and 3.8 kN, with different values for each model. In the analysis settings section, the number of steps was defined as two.

The bolt pretension, which was identified for each bolt, is the tension load developed in a fastener while tightening. So, in the first step, the bolt pretension load was equal to 25 kN, which was selected according to the literature and the bolt diameters. In the second step, the time was arranged to be 20 s, and the hysteretic loading was five cycles. In two steps, the analysis was defined by time, and the values of the initial time step, maximum and m time steps were assumed to be 0.05, 0.000001 and 0.1 s respectively.

Tab. 1 Details of material data

Material Property

Yield strength (MPa)

Tangent modulus (MPa)

Bolts

Bilinear isotropic hardening

640

1 450

Column

Bilinear isotropic hardening

275

1 450

Beam

Bilinear isotropic hardening

250

1 450

Angle

Bilinear isotropic hardening

250

1 450

3.2.2 Top-and-seat-angle connections with stiffeners Angle stiffeners 6, 8 and 10 mm thick were designed as a welded joint for the top-and-seat-angle connections, and beam stiffeners 5 mm thick were designed for the L91 and L82 model types. Hand-tightened full-threaded M8 grade 8.8 bolts were considered for all types of model in all analyses.

24

Steel Construction 14 (2021), No. 1

00_STCO_0121_Buch.indb 24

03.02.21 11:15

Fig. 3

ARTICLE

A. C. Aydin, A. Ardalani, M. Maali, M. Kiliç: Numeric modelling of innovative semi-rigid connections under cyclic loading

Two types of FE model and mesh pattern for top-and-seat-angle connections

Directional deformation, maximum shear stress and equivalent stress (von Mises) are important properties when finding the actual result for each model. By using these properties, it was possible to derive the force-deformation and the moment-rotation hysteresis curves. As a result of hysteretic loading, by completing the elastic deformations, plastic deformations were generated which caused energy dissipation in the models. Further, the value of this energy dissipation was calculated from the area under the moment-rotation hysteresis curve.

5

Analysis results

The force-deformation curve that explains the relationship between the applied force P and the corresponding deformation D between the members of connections was derived from the deformation of the specified node on the end of a beam affected by the load that was applied to this point. On the other hand, the M-q curve describes the relationship between the applied moment M and the corresponding rotation q between the members of connections. Essentially, the bending moment is derived by multiplying the distance between the load application points L and the applied force P at the beam’s end point:

M = PL (kNmm)

(1)

Further, the rotational deformation of the connection q is derived from the displacement D that occurs between the members: arctan ( ∆ ) (2) θ= (degree) L

Fig. 4

Details of bolted T-connection model

b. Model B240-T300-1-14(2) and B240-T240-1-14(4) bolted T-connection The models were analysed under vertical loading equal to 1.1 and 1.3 kN respectively. The connections had one row of M14 web bolts. c. Model B160-T140-2-10(5) and B160-T200-1-10(6) bolted T-connection The models were analysed under hysteretic loading equal to 3.75 and 1.3 kN respectively. The connections had two rows and one row of M10 web bolts respectively.

The M-q hysteresis curves of six types of bolted T-connection are shown in Fig. 6.

5.1. Characteristics of the analyses

The curves in Fig. 6 show that:

a. Model B240-T300-2-14(1) and B240-T270-2-14(3) bolted T-connection The models were analysed under hysteretic loading equal to 3.65 and 3.6 kN respectively. The connections had two rows of M14 web bolts.

– The maximum moment decreased when the rows of web bolts in the connection changed from two to one.

– The displacement and rotation increased when the rows of web bolts in the connection changed from two to one.

00_STCO_0121_Buch.indb 25

Steel Construction 14 (2021), No. 1 25

03.02.21 11:15

A. C. Aydin, A. Ardalani, M. Maali, M. Kiliç: Numeric modelling of innovative semi-rigid connections under cyclic loading Tab. 2 Details of bolted T-connections

Model

H= hymin/h1

Xmax Xmin Section thickness Beam (mm) (mm) of T-connections section

Number of rows of Bolt diameter bolts in beam web (grade 8.8)

B240-T300H‑Xmax-2-14 (1)

0.82

215

–

IPE 300

IPE240

2

14

B240-T300H‑Xmin-1-14 (2)

0.63

–

89

IPE 300

IPE240

1

14

B240-T270H‑Xmin-2-14 (3)

0.82

–

89

IPE 270

IPE240

2

14

B240-T240H‑Xmin-1-14 (4)

0.63

–

89

IPE240

IPE240

1

14

B160-T140H‑Xmax-2-10 (5)

0.57

126

–

IPE 140

IPE160

2

10

B160-T200H‑Xmin-1-10 (6)

0.63

–

54

IPE 200

IPE160

1

10

FE model

* HEB160 was used as column section in all models. ** Xmin = one row of bolts, Xmax = two rows of bolts, hy = length of angle, h1 = depth of beam web

– The maximum moment decreased with a reduction in the beam thickness. d. L91-tp6-BS5(1) and L91-tp6-BS5(2) top-and-seat-angle connection The model was analysed under hysteretic loading equal to 3.45 and 2.95 kN respectively. The length of angles, thickness of angle stiffeners and thickness of web stiffener were determined as 91, 6 and 5 mm respectively. e. L82-tp8(3) and L82-tp10(4) top-and-seat-angle connection The models were analysed for hysteretic loading equal to 3.5 and 3 kN respectively. The length of angles was chosen to be 82 mm and the thickness of angle stiffeners as 8 and 10 mm respectively.

The M-q hysteresis curves of four types of top-and-seatangle connections are shown in Fig. 7.

26

Fig. 5

Top and seat angle geometry and proposed three-dimensional semi-rigid joint

Steel Construction 14 (2021), No. 1

00_STCO_0121_Buch.indb 26

03.02.21 11:15

Tab. 3 Details of top-and-seat-angle connections

Model

Top & seat ­flange angle

Length of angle L (mm)

Stiffener thickness of top & seat angle tp (mm)

Web beam stiffeners

Stiffener ­thickness of beam (mm)

Bolt ­diameter (grade 8.8)

Xmax ve Ymax (mm)

L91-tp6-BS5 (1)

L60x60x6

91

6

YES

5

8

5.4

L91-tp6-BS5 (2)

L60x60x6

91

6

YES

5

8

5.4

L82- tp8 (3)

L60x60x6

82

8

NO

–

8

5.4

L82- tp10 (4)

L60x60x6

82

10

NO

–

8

5.4

ARTICLE

A. C. Aydin, A. Ardalani, M. Maali, M. Kiliç: Numeric modelling of innovative semi-rigid connections under cyclic loading

FE model

* IPE160 was selected as the beam section and HEB as the column section in all models. ** Xmax, Ymax = width of top and seat angles

The curves in Fig. 7 show that: – The displacement increased with a reduction in the length of angles in the stiffened models.

– The maximum moment increased with an increase in the stiffener thickness of the top and seat angle.

– The moment resistance increased when using a stiffener in the beam web.

– The rotational capacity decreased for the stiffened models.

– The rotational capacity increased with an increase in the length of angles.

There are two examples of M-q graph in the first load cycle of models, see Fig. 8 and Fig. 9.

The maximum moment values of bolted T-connections are presented in Fig. 8 and Tab. 3. The maximum moment for the B240-T300-1-14(2) model compared with the B240-T300-2-14(1) model decreased by about 70 %, with the decreasing ordinal number of web bolt rows from two to one. The maximum moment for the B240-T270-2-14(3) model compared with the B240-T300-2-14(1) model decreased by about 1.37 % with a change in the thickness of T-connections of IPE 300 to IPE 270 and reduction in the X value from 215 to 89 mm. The maximum moment for the B240-T240-1-14(4) model compared with the B240

00_STCO_0121_Buch.indb 27

T300-1-14(2) model increased by about 15.38 % with a change in the thickness of T-connections of IPE 300 to IPE 240 and a reduction in the X value from 215 to 89 mm. The maximum moment for the B160-T140-2-10(5) model and the B160-T200-1-10(6) model increased due to the use of a smaller bolt diameter (10 mm).

The energy dissipation values of bolted T-connections are presented in Tab. 4 and Fig. 9 for five-cycle loading. After the elastic deformation was completed, as a result of five hysteretic loadings, the energy dissipation values for the generated plastic deformation were 39, 23, 16, 12 and 10 % respectively in the first model, 39, 20, 16, 13 and 12 % respectively in the second model, 42, 21, 15, 12 and 10 % respectively in the third model, 38, 23, 16, 13 and 10 % respectively in the fourth model, 49, 20, 13, 10 and 8 % respectively in the fifth model, and 32, 23, 17, 15 and 13 % respectively in the sixth model.

Therefore, after switching from one cycle to another, as a result of five hysteretic loadings, the energy dissipation capacity decreased by about 16, 7, 4 and 2 % respectively in the first model, 19, 4, 3 and 1 % respectively in the second model, 21, 6, 3 and 2 % respectively in the third model, 15, 7, 3 and 3 % respectively in the fourth model, 29, 7, 3 and 2 % respectively in the fifth model, and 9, 6, 2 and 2 % respectively in the sixth model.

Steel Construction 14 (2021), No. 1 27

03.02.21 11:15

A. C. Aydin, A. Ardalani, M. Maali, M. Kiliç: Numeric modelling of innovative semi-rigid connections under cyclic loading

Fig. 6

Moment-rotation hysteresis curves of bolted T-connections

The energy dissipation for the B240-T300-1-14(2) model compared with the B240-T300-2-14(1) model decreased by about 87.4, 89, 87.6, 86.5 and 85.6 % with a decrease 28

in the ordinal number of web bolt rows from two to one, a reduction in the X value from 215 to 89 mm and H value from 0.82 to 0.63 mm. The energy dissipation for

Steel Construction 14 (2021), No. 1

00_STCO_0121_Buch.indb 28

03.02.21 11:16

Fig. 7

ARTICLE

A. C. Aydin, A. Ardalani, M. Maali, M. Kiliç: Numeric modelling of innovative semi-rigid connections under cyclic loading

Moment-rotation hysteresis curves of top-and-seat-angle connections

the B240-T270-2-14(3) model compared with the B240T300-2-14(1) model decreased by about 0.84, 16.22, 10.43, 8.65 and 8.45 % with a change in the thickness of the T-connections of IPE 300 to IPE 270 and a reduction in the X value from 215 to 89 mm. The energy dissipation for the B240-T240-1-14(4) model compared with the B240-T300-1-14(2) model increased by about 70.7, 75.4, 72.6, 85.3 and 68.13 % with a change in the thickness of the T-connections of IPE 300 to IPE 240. The energy dissipation for the B160-T200-1-10(6) model compared with the B160-T140-2-10(5) model decreased in the first two cycles by about 45 and 1.99 % respectively, and increased in the last three cycles by about 13.66, 19.95 and 24.18 % respectively with a decrease in the ordinal number of web bolt rows from two to one, and a change in the thickness of the T-connections of IPE 140 to IPE 200. The highest value of energy dissipation as shown in Tab. 4 and Fig. 9

00_STCO_0121_Buch.indb 29

was found for the B160-T140-2-10(5) model in the first cycle.

The maximum moment values of top-and-seat-angle connections are presented in Fig. 10 and Tab. 5. The maximum moment for the L91-tp6-BS5(2) model compared with the L91-tp6-BS5(1) model decreased by 14.49 % upon removal of the stiffener to the top and seat angle.

The maximum moment for the L82-tp10(4) model compared with the L82-tp8(3) model decreased by about 15.42 % upon removal of the stiffener to the top and seat angle and an increase in the thickness of the stiffener angles from tp 8 to tp 10. The maximum moment for the L82-tp8 and L82-tp10 models increased by about 3.87 and 2.82 % respectively with a reduction in the length L of the top and seat angle from 91 to 82 mm. The maximum moment for the L82-tp8(3) model compared with the L91Steel Construction 14 (2021), No. 1 29

03.02.21 11:16

A. C. Aydin, A. Ardalani, M. Maali, M. Kiliç: Numeric modelling of innovative semi-rigid connections under cyclic loading Tab. 4 Maximum moment values of bolted T-connections

Fig. 8

Model

Maximum moment (KNmm) Cycle

1

5 231.436

2

1 576.575

3

5 159.7

4

1 863.225

5

5 374.761

6

1 992.29

M-q diagram for the first load cycle of model B240-T300-H-Xmax-2-14

Fig. 10 Maximum moments of bolted T-connections Fig. 9

M-q diagram for the first load cycle of model L82- tp8

tp6-BS5(1) model increased by about 3.875 % upon removal of the beam stiffener. The maximum moment for the L82-tp10(4) model compared with the L91-tp6-BS5 (2) model increased by about 2.8 % upon removal of the beam stiffener.

After the elastic deformations were completed, as a result of five hysteretic loadings, the energy dissipation values for the plastic deformations generated were 29, 23, 19, 16 and 13 % respectively in the first model, 35, 22, 17, 14 and 12 % respectively in the second model, 30, 22, 18, 16 and 14 % respectively in the third model, and 34, 23, 17, 14 and 12 % respectively in the fourth model.

Therefore, after switching from one cycle to another, as a result of hysteretic loading, the energy dissipation capacity decreased by about 6, 4, 3 and 3 % respectively in the first model, 13, 5, 3 and 2 % respectively in the second model, 8, 4, 2 and 2 % respectively in the third model, and 11, 6, 3 and 2 % respectively in the fourth model.

The energy dissipation values of top-and-seat-angle connections are presented in Fig. 11 and Tab. 6 for five-cycle loading. The energy dissipation for the L91-tp6-BS5(2) model compared with the L91-tp6-BS5(1) model decreased by about 1.66, 19.18, 22.54, 24,99 and 28.04 % upon removal of the stiffener to the top and seat angle.

The energy dissipation for the L82-tp10(4) model compared with the L82-tp8(3) model decreased by about 0.62,

Tab. 5 Energy dissipation values of bolted T-connections

B240-T300-HXmin-1-14 (2)

B240-T270-HXmin-2-14 (3)

B240-T240-HXmin-1-14 (4)

B160-T140-HXmax-2-10 (5)

B160-T200-HXmin-1-10 (6)

1

700.65

88.746

694.74

302.77

1251.6

688.19

2

409.65

44.715

343.19

181.58

508.92

498.77

3

283.53

35.095

253.94

127.90

326.54

378.19

4

223.83

30.125

204.47

101.25

252.99

316.03

5

189.05

27.109

173.07

85.05

207.16

273.22

Cycle

B240-T300H-Xmax-2-14 (1)

Energy dissipation (kN.mm.degree)

Model

30

Steel Construction 14 (2021), No. 1

00_STCO_0121_Buch.indb 30

03.02.21 11:16

ARTICLE

A. C. Aydin, A. Ardalani, M. Maali, M. Kiliç: Numeric modelling of innovative semi-rigid connections under cyclic loading

Fig. 11 Energy dissipation diagram for bolted T-connections

Tab. 6 Maximum moment values of top-and-seat-angle connections

Model

Maximum moment (kNmm) Cycle

1

4 944.639

2

4 228.161

3

5 143.971

4

4 350.906 Fig. 12 Maximum moments of top-and-seat-angle connections

9.98, 16.53, 21.05 and 24.24 % upon removal of the stiffener to the top and seat angle. These results show that the rate of decrease for models with the stiffener to the top and seat angle is higher than that of the models without stiffeners for the angle. The energy dissipation for the L82-tp8(3) model compared with the L91-tp6-BS5(1) model increased by about 11.63, 4.89, 6.08, 8.85 and 10.36 % with a reduction in the length L of the top and seat angle from 91 to 82 mm. The energy dissipation for the L82-tp10(4) model compared with the L91-tp6-BS5 (2) model increased by about 12.55, 14.6, 12.85, 13.41 and 14.86 % with a reduction in length L of the top and seat angle from 91 to 82 mm. The energy dissipation for the L82-tp8(3) model compared with the L91-tp6-BS5(1)

model increased by about 11.63, 4.89, 6.08, 8.85 and 10.36 % upon removal of the beam stiffener. The energy dissipation for the L82-tp10(4) model compared with the L91-tp6-BS5 (2) model increased by about 12.55, 14.6, 12.85, 13.41 and 14.86 % upon removal of the beam stiffener.

6 Conclusions The aim of this study was to analyse the behaviour of bolted T-connections and top-and-seat-angle connections

Cycle

Energy dissipation (kN.mm.degree)

Tab. 7 Energy dissipation values of top-and-seat-angle connections

00_STCO_0121_Buch.indb 31

L91-tp6-BS5 (1)

L91-tp6-BS5 (2)

L82-tp8 (3)

L82-tp10 (4)

1

2 847.04

2 799.83

3 221.69

3 201.75

2

2 222.55

1 796.26

2 336.81

2 103.44

3

1 799.45

1 393.77

1 915.94

1 599.31

4

1 505.33

1 129.05

1 651.42

1 303.85

5

1 310.02

942.618

1 461.39

1 107.14

Steel Construction 14 (2021), No. 1 31

03.02.21 11:16

A. C. Aydin, A. Ardalani, M. Maali, M. Kiliç: Numeric modelling of innovative semi-rigid connections under cyclic loading

Fig. 13 Energy dissipation diagram for top-and-seat-angle connections

under hysteretic loading, evaluate the moment-rotation hysteresis curves and compare the quantity of energy dissipation that was derived from calculating the area under each loop of the moment-rotation curves for each model.

Therefore, the general conclusions that can be presented from this work are as follows: – For bolted T-connections • The maximum moment was increased by changing the thickness of the T-connections and changing the X values of the T-connections from Xmin to Xmax. In addition, the moment was affected by changing the diameter of the bolts.

• The displacement and rotational capacity were decreased by reducing the thickness of the connection’s web. Further, connections with long bolts showed a better capacity for rotation. By using bolts of the same grade and diameter, the rotational capacity was decreased when the ordinal number of web bolt rows in the connection was changed from two to one.

• By using bolts of the same grade and diameter, the energy dissipation was decreased when the ordinal number of web bolt rows in the connection had changed from two to one.

• The energy dissipation decreased by about 2–29 % after switching from one cycle to another in five hysteretic loadings.

– For top-and-seat-angle connections: • The moment was increased by using the stiffener in the beam web. Increasing the angle length and the thickness of stiffeners in connections also caused an increase in moment values.

• The displacement was increased by decreasing the angle length.

• For the stiffened top-and-seat-angle connections, the rotational capacity and energy dissipation values were increased by decreasing the angle length.

• The energy dissipation decreased by about 2–13 % after switching from one cycle to another in five hysteretic loadings.

During this study we used only von Mises stresses in the computer models and plastic deformations occurred as a result of these stresses. As a result of plastic deformations, energy dissipation occurred due to hysteretic loading.

However, the temperature due to plastic deformation during the test was not considered in the models.

References [1] Babu, S.; Sreekumar, S. (2012) A study on the ductility of bolted beam-column connections in: International Journal of Modern Engineering Research (IJMER) 2(5), pp. 3517– 3521.

[2] Sağıroğlu, M.; Aydın, A. C. (2015) Design and Analysis of non-linear space frames with semi-rigid connections in: Steel and Composite Structures 18(6), pp. 1405–1421.

[3] Faella, C.; Piluso, V.; Rizzano, G. (2000) Structural steel semirigid connections: theory, design and software in: New Directions in Civil Engineering., CRC Publishers.

32

[4] Díaz, C.; Martí, P.; Victoria, M.; M. Querin, O. (2011) Review on the modeling of joint behavior in steel frames in: Journal of Constructional Steel Research 67, pp. 741–758.

[5] Wilson, W. M.; Moore, H. F. (1917) Tests to determine the rigidity of riveted joints in steel structures. Engineering Experiment Station, Bulletin 104, University of Illinois, Urbana, USA. [6] Goverdhan, A. V. (1984) A collection of experimental moment-rotation curves and valuation of prediction equations

Steel Construction 14 (2021), No. 1

00_STCO_0121_Buch.indb 32

03.02.21 11:16

for semi-rigid connections (master thesis), Vanderbilt University, Nashville (TN).

[7] Nethercot, D. A. (1985) Steel beam-to-column connections: a review of test data and its applicability to the evaluation of joint behaviour in the performance of steel frames. CIRIA report 338.

[8] Nethercot, D. A. (1985) Utilization of experimentally obtained connection data in assessing the performance of steel frames in: Chen W. F. (ed.) Connection flexibility and steel frames. Detroit: Proc. of session sponsored by ASCE Structural Division.

[9] Steel Structures Research Committee (1931) First report.

London: Dept. of Scientific & Industrial Research, HMSO. [10] Steel Structures Research Committee (1934) Second report.

London: Dept. of Scientific & Industrial Research, HMSO. [11] Steel Structures Research Committee (1936) Final report.

London: Dept. of Scientific & Industrial Research, HMSO. [12] Kishi, N.; Chen, W. F. (1986) Steel connection data bank program, Structural Engineering, 2nd ed., Report No. CESTR86-18, School of Civil Engineering, Purdue University, West Lafayette.

[13] Abdalla, K. M.; Chen, W. F. (1995) Expanded database of semi-rigid steel connections in: Computers & Structures 56(4), pp. 553–564.

[14] Weynand, K. (1992) SERICON I-databank on joints building frames in: Proc. of COSTC1, 1st State of the Art Workshop on Semi-Rigid Behavior of Civil Engineering Structures, pp. 463–474.

[15] Weynand, K.; Huter, M.; Kirby, P. A.; Simões, da Silva L. A. P.; Cruz, P. J. S. (1998) SERICON-databank on joint in building frames in: Proc. of COSTC1, 1st State of the Art Workshop on Semi-Rigid Behavior of Civil Engineering Structures, pp. 463–474.

[16] Gerardy, J. C.; Schleich, J. B. (1991) Semi-rigid action in steel frame structures. Report No. 7210-SA1507, Arbed Recherches, Luxembourg.

[17] Cruz, P. J. S.; Simões da Silva L. A. P.; Rodrigues D. S.; Simões R. A. D. (1998) SERICON II, database for the semirigid behaviour of beam-to-column connections in seismic regions in: Journal of Constructional Steel Research 46(1– 3), pp. 233–234.

[18] Astaneh Asl, A.; Nader, M. N.; Malik, L. (1989) Cyclic Behavior of Double Angle Connections in: J.Struct.Eng. 115(5), pp. 1101–1118.

[19] Azizinamini, A.; Bradbum, J. H.; Radziminski, J. B. (1985) Static and cyclic behavior of semi-rigid steel beam-column connections, Dept. of Civ. Engrg., Univ. of South Carolina, Columbia, S.C. [20] Chen, W. F.; Lui, E. M. (1991) Stability Design of Steel Frames. London: CRC Press.

[21] Abolmaali, A.; Kukreti, A. R.; Razavi, H. (2003) Hysteresis Behaviour of Semi-Rigid Double Web Angle Steel Connections in: Journal of Constructional Steel Research 59, pp.

1057–1082.

[22] Shi, Y.; Shi, G.; Wang, Y. (2007) Experimental and Theoretical Analysis of the Moment-Rotation Behaviour of Stiffened Extended End-Plate Connections in: Journal of Constructional Steel Research 63, pp. 1279–1293.

[23] European Committee for Standardization (CEN) (2005) Design of steel structures. Part 1.8: Design of joints. Stage 49 draft, Brussels.

00_STCO_0121_Buch.indb 33

[24] Maali, M.; Kılıç, M.; Aydın, A. C. (2016) Experimental Model of the Behaviour of Bolted Angles Connections with Stiffener in: International Journal of Steel Structures 16(3), pp. 719–733.

[25] Maali, M.; Kılıç, M.; Sağıroğlu, M.; Aydın, A. C. (2017) Experimental Model for Predicting the Semi-Rigid Connections Behaviour with Angles and Stiffeners in: Advances in Structural Engineering 20(6) pp. 884–895.

[26] Maali, M.; Kılıç, M.; Aydın, A. C. (2019) Experimental behavior of bolted connections with stiffeners in: Steel Construction Design and Research 12, No. 2, pp. 105–113.

[27] Maali, M.; Kılıç, M.; Yaman, Z.; Ağcakoca, E.; Aydın, A. C. (2019) Buckling and Post-Buckling Behavior of Various Dented Cylindrical Shells Using CFRP Strips Subjected to Uniform External Pressure: Comparison of Theoretical and Experimental Data in: Thin-Walled Structures 137, pp. 29– 39,.

[28] Maali M.; Aydin A. C.; Showkati H.; Sağıroğlu M.; Kiliç M. (2018) The effect of longitudinal imperfections on thinwalled conical shells in: Journal of Building Engineering 20, pp. 424–441.

[29] Sagiroglu, M.; Maali, M.; Kılıç, M.; Aydın, A. C. (2018) A Novel Approach for Bolted T-Stub Connections in: International Journal of Steel Structures 18, No. 3, pp. 891–909.

[30] Aydin, A. C.; Özkaya, S. G. (2018) The finite element analysis of collapse loads of single-spanned historic masonry arch bridges (Ordu, Sarpdere Bridge) in: Engineering Failure Analysis 84, pp. 131–138.

[31] Aydın, A. C.; Maali, M.; Kılıç, M.; Sagiroglu, M. (2015) Experimental Investigation of Sinus Beams with End-Plate Connections in: Thin-Walled Structures 97, pp. 35–43.

[32] Aydın, A. C.; Kılıç, M.; Maali, M.; Sagiroglu, M. (2015) Experimental Assessment of the Semi-rigid Connections Behavior with Angles and Stiffeners in: Journal of Constructional Steel Research 114, pp. 338–348.

[33] Maali, M.; Aydin, A. C.; Sagiroglu, M. (2015) Investigation of innovative steel runway beam in industrial building in: SADHANA Academy Proc. in Engineering Sciences, pp.

2239–2251.

[34] Abidelah, A.; Bouchair, A.; Kerdal, D. E. (2012) Experimental and Analytical Behavior of Bolted End-Plate Connections with or without Stiffeners in: Journal of Constructional Steel Research 76, pp. 13–27.

[35] Limaa, L. R. O.; Veradea, S. A. L.; Vellascob, P. C. G.; Silvac, L. S. (2002) Experimental and mechanical model for predicting the behavior of minor axis beam-to-column semi-rigid joints in: International Journal of Mechanical Sciences, 44, pp. 1047–1065.

[36] Korucuk, F. M. A.; Maali, M.; Kılıc, M.; Aydın, A. C. (2019) Experimental Analysis of the Effect of Dent Variation on the Buckling Capacity of Thin-Walled Cylindrical Shells in: Thin-Walled Structures 143, pp. 1–13.

[37] Sağıroğlu, M. (2018) Experimental evaluation of the postfire behavior of steel T-component in the beam-to-column connection in: Fire Safety Journal 96, pp. 153–164.

[38] Sagiroglu, M., Aydin, A.C. (2015) Design and analysis of non-linear space frames with semi-rigid connections in: Steel and Composite Structures, Int. Journal 18, pp.1405– 1421.

ARTICLE

A. C. Aydin, A. Ardalani, M. Maali, M. Kiliç: Numeric modelling of innovative semi-rigid connections under cyclic loading

Steel Construction 14 (2021), No. 1 33

03.02.21 11:16

A. C. Aydin, A. Ardalani, M. Maali, M. Kiliç: Numeric modelling of innovative semi-rigid connections under cyclic loading Authors Abdulkadir Cüneyt Aydin (corresponding author) acaydin@atauni.edu.tr Ataturk University Engineering Faculty Department of Civil Engineering 25030, Erzurum Turkey

Mahmut Kiliç mahmut.kilic@atauni.edu.tr Ataturk University Engineering Faculty Department of Civil Engineering 25030, Erzurum Turkey

Aysan Ardalani aysan.ardalan@gmail.com Ataturk University Engineering Faculty Department of Civil Engineering 25030, Erzurum Turkey Mahyar Maali mahyar.maali@erzurum.edu.tr Erzurum Technical University Faculty of Engineering & Architecture Department of Civil Engineering 25050, Erzurum Turkey

How to Cite this Paper Aydin, A. C.; Ardalani, A.; Maali, M.; Kiliç, M. (2021) Numeric modelling of innovative semi-rigid connections under hysteric loading. Steel Construction 14, No. 1, pp. 22–34. https://doi.org/10.1002/stco.201900037 This paper has been peer reviewed. Submitted: 29. August 2019; accepted: 24. January 2020.

Prof. Markus Knobloch, Prof. Ulrike Kuhlmann, Prof. Andreas Taras et al.

Structural member stability in the second generation of Eurocode 3 26 March 2021 · 10.00–12.00 a.m. CET

www.ernst-und-sohn.de/stco-seminar

STCO-OLS-2-Knobloch.indd 23

34

08.01.2021 11:57:24

Steel Construction 14 (2021), No. 1

00_STCO_0121_Buch.indb 34

03.02.21 11:16

1185.ind

Partnership with academic institutions Ernst & Sohn with their parent company John Wiley & Sons, Inc. has signed a contract with the Projekt DEAL in 2019.

The Projekt DEAL represents as a consortium about 700 academic institutions in Germany. In order to support the general furthering of scientific research, Wiley and the Project Deal have together initiated three new initiatives as a partnership.

The trendsetting agreement will enable researchers from all the Projekt DEAL institutions to publish articles in Wiley journals with open access.

You can find more information about the agreement in the press release from Wiley.

2

Steel Construction

Volume 12 May 2019 ISSN 1867-0520

Design and Research

 Authorised

authors from participating institutions can publish with open access and profit from reading access to the journals of Wiley and Ernst & Sohn.

– Eurocode 4 Development – Local buckling strength of HSS stub cruciform column – Reusing steel parts from single-storey buildings – MOCAPE – Experimental behaviour of bolted connections with stiffeners – Box girder selection for cable-supported railroad bridges – Tension-shear interaction of HS bolts in fire – Dynamic behaviour of unbraced steel frames resting on soft ground

Ernst & Sohn is involved in this partnership with the journals Civil Engineering Design and Steel Construction and from 2019 will offer publications under the open access model.

ISSN 2625-073X

 Authors

VOLUME 2 / OCTOBER 2020

from Projekt DEAL institutions can publish research and overview articles with open access in Wiley journals, maintaining the copyright to their works without further costs.

– European buckling curves for aluminium members – Review of Wöhler’s fatigue strength research

04

Print issues of Steel Construction, which is also available in a printed version, can be ordered in addition to the online variant. This provides the reader with supplementary industry reports and product information.

If you have any questions, please contact: marketing@ernst-und-sohn.de For more information and to check eligibility, visit: www.ernst-und-sohn.de/DEALWiley

www.ernst-und-sohn.de/en/deal 1185.indd 12 00_STCO_0121_Buch.indb 1

1185126_hk

Ernst & Sohn +49 (0)30 470 31-236 marketing@ernst-und-sohn.de 03.11.20

03.11.2020 16:44:06 03.02.21 11:16

Chefredakteur: Prof. Dr. Konrad Bergmeister Editorial Board: Prof. Dr. Peter Mark, Prof. Dr. Manfred Curbach, Prof. Dr. Oliver Fischer, Prof. Dr. Jan Akkermann, Dipl.-Ing. Torsten Schoch

Call for Papers Civil Engineering Design

engl. Sprache, 6 Ausgaben pro Jahr interdisziplinärer und materialunabhängiger Ansatz

ISSN 2625-073X

hybride Open-Access Zeitschrift, ausschließlich Online VOLUME 2 / DECEMBER 2020

-

05/ 06

fokussiert auf wissenschaftliche Veröffentlichungen erfahrener Beirat, kurze Begutachtungsund Veröffentlichungszeiträume Manuskripteinreichung und Begutachtungsverfahren über ScholarOne Einfachblindgutachten unabhängiger Experten

Die Zeitschrift Civil Engineering Design befasst sich mit innovativen theoretischen, numerischen und experimentellen Methoden für aktuelle und neuartige Baustoffe wie Beton, Stahl, Aluminium, Glas, Holz, Mauerwerk, Verbundwerkstoffe und allen Aspekten der konzeptionellen, baulichen und leistungsbezogenen Planung, der experimentellen Prüfung und der numerischen Modellierung von Errichtung, Instandhaltung und Abriss für den gesamten Lebenszyklus von Bauwerken. Abgerundet wird dies durch die Einbeziehung der Geotechnik und Bodenmechanik aus bautechnischer Sicht.

1219.indd 11 00_STCO_0121_Buch.indb 2

EINREICHUNGEN Sie sind eingeladen am Start dieser neuen Zeitschrift aktiv teilzunehmen, sie zu formen und die Entwicklung ihrer Ausrichtung zu bestimmen. mc.manuscriptcentral.com/cend Dirk Jesse (Managing Editor) + 49 (0)30 470 31-275 dirk.jesse@wiley.com

09.12.2020 13:24:34 03.02.21 11:16

ARTICLE

Ali Munesi, Mohammadkazem Sharbatdar, Majid Gholhaki

ARTICLE

DOI: 10.1002/stco.201900047

An investigation into the factors influencing the cyclic behaviour of buckling-restrained steel plate shear walls Steel plate shear walls (SPSW) are being increasingly used in steel or concrete structures as lateral load-resisting systems.

Shear buckling is one of the major shortcomings of the SPSW and so to address this issue, buckling-restrained steel plate shear walls (BRSPSW) have started to appear. Owing to the novel concept of this structural system, this paper aims to investigate the effect of factors influencing the response of BRSPSWs. For this purpose, a parametric study was conducted using ABAQUS software. Based on the results acquired from the hysteretic curves, an increase in the concrete compressive strength does not markedly affect the ductility and energy dissipation capacity. Moreover, it was observed that as the width of the gap between concrete panel and steel plate grows, the energy dissipation and response modification factor are reduced. Besides, the results indicate that as steel strength increases, so energy dissipation increases from 0.7 to 11.7 %.

Accordingly, based on a comparison between the rate of improvement in shear capacity arising from an increase in the strength of the concrete panels, frame and steel plate, it is concluded that it would be much more rational to increase the concrete strength so that a high shear capacity can be achieved for the BRSPSW. Lastly, in all models, as the gap width increases from 0 to 20 mm and 20 to 35 mm, ductility decreases by 41 and 30 % respectively.

and concrete panels that are connected to either one or both sides of the plate using shear connectors. In these walls there is usually a gap between the plate and the panels to allow the panels to act as a stiffener [8, 9].

Numerous studies have been conducted on stiffened and unstiffened SPSWs, whereas the behaviour of BRSPSWs has not been sufficiently investigated [10].

Astanehasl and Qiuhong [11, 12] originally conducted a series of tests on BRSPSWs and comparisons were made with the behaviour of SPSWs. The comparisons indicated that damage induced in the concrete panels and bolts are less intense than those of SPSWs and also that the gap in BRSPSWs leads to these panels being damaged less when subjected to large cyclic loads.

In another study, Arabzadeh et al. [13] concluded that the application of the BRSPSW system requires the presence of strong columns in multi-storey buildings as high bending forces develop and the presence of such columns could significantly enhance the seismic performance of the system.

Keywords buckling-restrained shear plate steel wall (BRSPSW); gap width; stiffness; strength; response modification factor R; concrete panel thickness; steel plate

1 Introduction Steel plate shear walls (SPSW) are regarded as economic systems that properly absorb seismic energies and provide high levels of strength to resist lateral loads [1]. In the past, to prevent out-of-plane buckling triggered by shear yielding, either thick plates or several stiffeners had to be employed [2]. SPSWs without stiffeners have been utilized in recent years with the aim of reducing costs and facilitating the construction process [3–5]. To limit the slenderness of the SPSWs in order to develop shear yielding instead of shear buckling, the stiffeners have to be welded to the steel plates, which impose additional costs on the project.

Recently, a simpler technique has been developed in which precast concrete panels are employed to restrain the out-of-plane deformations, and these are technically known as buckling-restrained steel plate shear walls (BRSPSW) [6, 7]. The BRSPSW consists of a steel plate

00_STCO_0121_Buch.indb 35

Fig. 1

Schematic view of a buckling-restrained steel plate shear wall (BRSPSW)

© 2020 Ernst & Sohn Verlag für Architektur und technische Wissenschaften GmbH & Co. KG, Berlin. Steel Construction 14 (2021), No. 1 35

03.02.21 11:16

A. Munesi, M. Sharbatdar, M. Gholhaki: An investigation into the factors influencing the cyclic behaviour of buckling-restrained steel plate shear walls

Similarly, Rasouli et al. [14] perceived that to enhance the shear capacity, a specific thickness is required for the panels beyond which not only does the capacity not increase, but also the seismic mass of the structure increases and leads to unsatisfactory effects on the structure.

Li and Li [15] studied the seismic behaviour of composite steel plate shear walls (BRSPSW) in which the concrete had been replaced by an engineered cementation composite (ECC) to tackle the brittle shear failure mechanism. Their numerical analyses indicated that the use of ECC leads to a better performance compared with the concrete.

Shafiei et al. [16, 17] applied numerical approaches to study the effect of panel thickness on the behaviour of the BRSPSW and concluded that such panels improve the shear strength and energy absorption capacity. In a followup study, they investigated the effect of openings on the behaviour of the BRSPSWs and observed that in the presence of the square opening, global and local elastic buckling is effectively prevented by the concrete panels, yielding first starts in the infill plate.

In 2018 Meghdadian and Ghalehnovi [18] attempted to study the effect of an opening on the seismic behaviour of the composite steel plate shear walls. They concluded that the inclusion of the opening reduces the stiffness and energy absorption capacity of the wall. To compensate partially for these losses, they proposed placing reinforcing bars or steel plates at the corners of the opening.

Pachideh et al. [19] proposed a novel simplified model called the three-strip model in which the infill plates of the SPSWs were replaced by three tension-only strips. To evaluate the efficiency of the proposed model, the capacity curves of structures equipped with SPSWs obtained from both experimental tests and numerical models were compared and, promisingly, an acceptable agreement between the results was achieved. By conducting a para­ meter study, Pachideh et al. managed to find that the wall aspect ratio and the flexibility of the boundary columns do not affect the accuracy of the proposed approach and that the three-strip and conventional strip models both yield comparatively identical results. In another study, Pachideh and Gholhaki [20] assessed damage indices for the SPSWs based on Park-Ang and lateral displacement and. They concluded that the displacement damage index defines the boundary limits in such a way that structures could be categorized in IO and LS performance level, which is likely a drawback compared with the other two indices. Yadegari et al. [21] conducted a series of non-linear seismic analyses on multi-storey structures equipped with composite steel plate shear walls (CSPSW). They concluded that the boundary columns and reinforced concrete (RC) panel together provide a high shear strength for the frame (up to 30 %) which is typically overlooked by AISC 341-10 [9]. In 2019 Pachideh et al. [22] managed to determine damage indices for SPSW frames with different height ranges. Accordingly, under different 36

performance levels, damage to each structure was calculated using the Park-Ang damage index, maximum relative displacement index, deformation index and plastic ductility index. Based on the results, it was found that the use of SPSWs in taller buildings leads to more desirable results compared with low- and medium-rise structures.

Afshari and Gholhaki [23] carried out a numerical study of the rate of decrease in shear strength of SPSWs incorporating openings with arbitrary locations. They managed to develop empirical and dimensionless equations to determine the value of strength degradation due to the presence of openings. The numerical results indicated that the proposed equations could be reliably employed for all rectangular panels with a width-to-height ratio > 1 and square panels with any thickness.

Gholhaki et al. [24] conducted a numerical investigation into the effect of subpanel size on the non-linear behaviour of the SPSWs. For this purpose, they considered five cases of SPSW, both stiffened and unstiffened, and then conducted a pushover analysis to acquire response modification and ductility factors. Based on the results, as the subpanel size decreases, so the non-linear characteristics of the SPSW are enhanced significantly. In another study, Gholhaki et al. [25] studied the overstrength, ductility and response modification factors of the structures benefitting from the SPSWs as their lateral load-resisting system using incremental dynamic analyses (IDA). The results indicate that for high-, medium- and low-rise structures, response modification factors have to be nearly 8 and 9.

Based on the literature, it is concluded that the seismic performance of BRSPSWs has not received much attention yet and more studies are required in order to obtain a better insight into the seismic design parameters of such systems. Hence, this study aims to help practitioners gain a better understanding by investigating the effects of the factors with a dominant influence on such systems. For this purpose, the width of the gap between steel plate and concrete panel, the strength of the surrounding columns, the compressive strength of concrete and the yield strength of the plate were selected to evaluate their effects on response modification factor, ductility, rate of energy dissipation and stiffness of the system.

2

Numerical modelling verification

The commercial finite element software ABAQUS/ Explicit was used for the numerical modelling [26]. The 3D solid elements (C3D8R) were selected to simulate the concrete materials in all models for which full integration was used to calculate the required parameters (C3D8R: 8-node linear brick element). Shell elements (S4R) were used for the steel plates whose computations were conducted via a reduced integration approach. Three-dimensional beam elements (B31) were used for longitudinal reinforcement and 2-node three-dimensional truss elements (T3D2) for transverse reinforcing bars. It should be noted that in all models, the large displacement effects

Steel Construction 14 (2021), No. 1

00_STCO_0121_Buch.indb 36

03.02.21 11:16

Fig. 2

ARTICLE

A. Munesi, M. Sharbatdar, M. Gholhaki: An investigation into the factors influencing the cyclic behaviour of buckling-restrained steel plate shear walls

Test setup and configuration [13]

Tab. 1 Properties of steel components

Steel sections

Elastic modulus [MPa]

Ultimate strength [MPa]

Yield strength [MPa]

Flanges of beams and columns

308

479

200 000

Webs of beams and columns Steel plates Bolts Rebars

285 268 1 080 336

446 415 1 290 492

200 000 2 000 000 200 000 203 000

Tab. 2 Concrete properties

Tensile strength [MPa]

Compressive strength [MPa]

Elastic modulus [MPa]

4

43

30 071

have been taken into account so that the local buckling and post-buckling behaviour of the coupling beams could be simulated. Moreover, the model tested experimentally

by Arabzadeh et al. was taken as the reference for verification (see Fig. 1) [13].

3

Constitutive models

The concrete damaged plasticity model provided in ABAQUS was employed to define the concrete material.

This approach accounts for both tensile and compressive failures of concrete material that is a three-dimensional continuum plasticity-based model [26]. The values of compressive strength and modulus of elasticity are given

00_STCO_0121_Buch.indb 37

Tab. 3 Sections used for experimental specimens

Column

2IPE100+2PL100×5

Beam Thickness of steel plate (mm) Bolt diameter (mm) Rebar diameter (mm) Thickness of concrete panel (mm)

2IPE100 2 20 3 30

in Tab. 2. In addition, the classical metal plasticity model provided in ABAQUS was utilized for simulating the steel behaviour. This model uses the von Mises yield surface with dependent plastic flow to enable the definition of the isotropic yielding. Using this model, it is possible to Steel Construction 14 (2021), No. 1 37

03.02.21 11:16

A. Munesi, M. Sharbatdar, M. Gholhaki: An investigation into the factors influencing the cyclic behaviour of buckling-restrained steel plate shear walls Tab. 4 Sizes of elements used in sensitivity analysis

Type of element

Element size (mm)

Number of elements

Total number of elements

Frame

30

1 312

5 662

Concrete panel

20

1 250

5 662

Steel plate

30

324

5 662

Bolts

3

510

5 662

Rebars

5

2 266

5 662

define perfectly plastic or isotropic/kinematic hardening behaviour [26].

The model to be studied here is a one-storey frame including one bay with moment-resisting connections (scale 1:4).

The steel and concrete properties and the section specifications are given in Tab. 1–3.

4

Loading protocol

The models were loaded by the ATC-42 loading protocol as depicted in Fig. 3. As can be seen, the displacement control method was adopted to load the models laterally.

Sensitivity analysis To determine the optimal mesh size, different sizes were examined for each component. Accordingly, the mesh size for steel plate, frame, bolts and panels were in the

range 10 to 120, 10 to 40, 3 to 20 and 10 to 40 mm respectively. Eventually, based on the sensitivity analysis, the sizes given in Tab. 4, were selected.

5

Evaluation of the results

The numerical and experimental hysteretic curves are illustrated in Fig. 4 and, as can be seen, there is good agreement between them.

To scrutinize the process of verification and compare the results quantitatively, the backbone curves of both numerical and experimental models were plotted, and these contain useful data regarding the behavioural parameters of the specimens (Fig. 5).

Accordingly, initial stiffness, ultimate strength and ductility were the parameters taken for the sake of quantitative comparison.

As presented in Tab. 5, there is only a 5 % difference bet­ ween the experimental and numerical values, which verifies the validation and accuracy of the modelling process.

6

Parametric study

After the process of verification, to understand better the effects of key parameters on the behaviour of the CSPSW system, a parametric study was carried out using ABAQUS

Fig. 3

ATC-24 loading protocol

Fig. 4

a) Comparison between experimental and numerical hysteretic curves, and b) distribution of the stresses developed in the specimen

38

Steel Construction 14 (2021), No. 1

00_STCO_0121_Buch.indb 38

03.02.21 11:16

Tab. 5 Comparison of the behavioural parameters obtained from the capacity curves

Sample

Fu

Num

F0u Experimental Analysis

Exp

390 397

 µExp     µNum  4.6 4.5

K0

Num

K0

µ=

Exp

84.78 88.22

∆u ∆y

585 600

Du (mm)

Fu (kN)

K0 (kN/mm)

Dy (mm)

Vy (kN)

26 24

5.65 5.33

1.04 1.04

1.06 1.06

1.02 1.02

ARTICLE

A. Munesi, M. Sharbatdar, M. Gholhaki: An investigation into the factors influencing the cyclic behaviour of buckling-restrained steel plate shear walls

Tab. 6 Specifications of elements used in numerical models

Length

Dimensions

Element

Columns Beams Steel plate (mm) Bolts (mm) Rebar (mm) Concrete panel (mm)

BOX 300×300×8 PG F200×12W300×6 PL 300×300×3-4-5 20 8 CTHK 30-40-50

L = 3 000 L = 3 000 – – – –

software [19]. As shown in Fig. 6, the boundary columns were BOX 300×300 mm and the thickness of the steel plate and stiffeners 8 mm, and so the dimensions of the flanges and web of the beams was 150×8 and 300×8 mm respectively. As mentioned earlier, the loading protocol specified by ATC24 was applied to the models. The 3D image and cross-section of the wall are shown in Fig. 6.

The specifications of the models used for the numerical analyses are given in Tab. 6.

6.1

Influencing factors

The effects of concrete panel thickness, concrete compressive strength and width of the gap between the panels and steel plates were investigated in this study. The values considered for each one of these factors are presented in Tab. 7.

Fig. 5

Comparison between experimental and numerical load-displacement curves

Fig. 6

Schematic representation of the numerical models

00_STCO_0121_Buch.indb 39

As mentioned before, to study the behaviour of models, cyclic loading was applied and a hysteretic curve extracted for each model. Next, the backbone curves were plotted

Steel Construction 14 (2021), No. 1 39

03.02.21 11:16

A. Munesi, M. Sharbatdar, M. Gholhaki: An investigation into the factors influencing the cyclic behaviour of buckling-restrained steel plate shear walls Tab. 7 Model values of influencing factors for parametric study

Parameter

Dimensions

Thickness of concrete panel [P] Concrete compressive panel [C] Gap width [D]

30 25 0

40 35 20

Unit 50 45 35

mm MPa mm

to ascertain the behavioural parameters of dissipated energy, response modification factor, initial stiffness and ultimate strength.

6.2

Analysis of the results

This section attempts to study the behaviour of the BRSPSW by investigating the effect of the key behavioural para­ meters so that a comprehensive insight can be obtained and thus facilitate the design process of this novel structural system. It is worth noting that to study the behaviour more accurately, the role of the key parameters has been evaluated considering different strength states for the steel components. Subsequently, both steel grades, ST 37 and 52, were taken for the frame and steel plate. It

should be noted that in the respective table, W and F represent the steel plate and frame respectively.

6.3

Energy dissipation

During the cyclic loading, the fraction of the energy dissipated in each cycle is equal to the area under the loaddisplacement curve as shown in Fig. 8. Accordingly, some of the energy dissipated in all cycles will represent the total amount of energy dissipation.

Tab. 8 presents the values of dissipated energy. Figs. 8 to 10 enable a better investigation of the effect of each para­meter on the general behaviour of the system.

As can be seen in Fig. 8, a comparison of the dissipated energy rates indicates that an increase in compressive strength from 25 to 35 MPa has improved the energy dissipation but a further increase in the strength does not significantly affect the energy dissipation. Moreover, it can be seen that as the steel strength increases, so the rate of improvement in energy dissipation rises, with minimum and maximum rates of improvement equal to 0.7 and 11.7 % for W37-F37 and W52-F52 respectively.

However, it should be noted that in the case where highstrength steel is used for frame elements, the energy has been markedly dissipated (approx. 33 %). On this basis it can be concluded that the energy dissipation is more affected by the boundary elements (i.e. frames) than the steel plate and concrete panels.

Fig. 7

Energy dissipation at ith cycle

Fig. 8

Dissipated energy versus concrete compressive strength

40

Steel Construction 14 (2021), No. 1

00_STCO_0121_Buch.indb 40

Fig. 9 demonstrates the trend in energy dissipation variations versus the width of the gap between steel plate and concrete panels. As can be seen, an increase in the gap width generally had an adverse effect on the energy dissipation capacity. Importantly, there is a threshold limit for an increase in the gap width, beyond which

03.02.21 11:16

Tab. 8 Rate of energy dissipation versus change in effective parameters

No.

Variable parameter

Model

E [kN.m] W37–F37

W52–F37

W37–F52

W52–F52

P50

C25

T4

D00

288

306

430

392

P50

C35

T4

D00

290

310

456

444

3

P50

C45

T4

D00

295

310

460

444

4

P50

C25

T4

D00

270

306

339

392

1 2

Compressive strength

P50

C25

T4

D20

96

300

313

377

6

P50

C25

T4

D35

78

103.5

199

234

7 8 9

P30 P40 P50

C25 C25 C25

T4 T4 T4

D00 D00 D00

255 275 294

– – –

276 342 386

85 164 274

5

Gap width

Panel thickness

ARTICLE

A. Munesi, M. Sharbatdar, M. Gholhaki: An investigation into the factors influencing the cyclic behaviour of buckling-restrained steel plate shear walls

energy dissipation decreases drastically given the fact that exceeding this specific limit leads to buckling in the steel plate and, consequently, undermines the restrictive impact of the concrete panel. For instance, in the case of W52-F52, the rate of energy dissipation for gap widths of 0 and 20 mm is more or less the same, but as the width increases to 35 mm, the energy dissipation capacity declines by 38 %.

Fig. 10 illustrates the effect of concrete panel thickness on energy dissipation capacity. As can be seen, the increase in the thickness of the panels has enhanced the energy

dissipation capacity. Moreover, a comparison of the energy dissipation rates of W52-F37 and W37-F-52, which are equal to 324, 208 and 140 % for thickness values of 30, 40 and 50 mm respectively, reveals that an increase in the strength of frame elements reduces the ductility and the area under the capacity curves, proving the fact that less energy has been dissipated compared with the case where steel with a lower strength has been employed.

This result proves the great importance of the boundary elements for the general behaviour of the system in terms of energy dissipation.

6.4

Response modification factor R and ductility

The response modification factor is derived as presented in the following equation:

Fig. 9

Dissipated energy versus gap width

Ru =

Ve Ve Vd Vy = × × (1) Vs Vd Vy Vs

Where Ve, Vy and Vd represent, respectively, the base shear assuming elastic behaviour for the structure, the base shear when the global plastic state is reached and the capacity of the structure at the target displacement or the displacement corresponding to the maximum base shear.

Ductility is defined as the ratio of the displacements corresponding to failure to that of yield indicating the nonlinear extent of the behaviour.

Fig. 10 Dissipated energy versus concrete panel thickness

00_STCO_0121_Buch.indb 41

Figs. 12 and 13 demonstrate the influence of concrete compressive strength on the ductility ratio and the response modification factor. According to Fig. 12, an increase in compressive strength has not affected the ductility particularly, which is attributed to the direct relation between ductility and displacements and, consequently, stiffness, which is not affected by the concrete strength.

Fig. 13 indicates that an increase in concrete strength has enhanced the response modification factor. Interestingly, the response modification factor of the W37-F37 model Steel Construction 14 (2021), No. 1 41

03.02.21 11:16

A. Munesi, M. Sharbatdar, M. Gholhaki: An investigation into the factors influencing the cyclic behaviour of buckling-restrained steel plate shear walls

Fig. 11 Key parameters of the load-displacement curve used to calculate the response modification factor

Fig. 12 Ductility ratio versus concrete compressive strength

Fig. 14 Ductility ratio versus gap width

Fig. 13 Response modification factor versus concrete compressive strength

Fig. 15 Response modification factor versus gap width

has been more profoundly affected, increasing by 11 and 14 % when the strength rises from 25 to 35 MPa and 35 to 45 MPa respectively.

and 17. According to Fig. 16, an increase in panel thickness and, consequently, a rise in the stiffness allowing larger displacements to be resisted, has managed to increase the distance between yield and ultimate displacements and has eventually enhanced ductility. Also, as shown in Fig. 17, an increase in concrete panel thickness improved the response modification factor of all models.

Figs. 14 and 15 illustrate the trend in variations in ductility and response modification factor versus gap width.

According to Fig. 14, an increase in gap width has reduced the ductility, which is due to the rapid occurrence of the buckling in the steel plate. As can be seen, the rate of decline in all models is approximately equal and as the width increased from 0 to 20 mm and 20 to 35 mm, ductility decreased by 41 and 30 % respectively.

The trend in the ductility and response modification factor versus concrete panel thickness is presented in Figs. 16 42

6.5

Stiffness and shear capacity

Initial stiffness denotes the ratio of force to displacement obtained from the idealized load-displacement curve, and shear capacity represents the maximum strength of the system.

Steel Construction 14 (2021), No. 1

00_STCO_0121_Buch.indb 42

03.02.21 11:16

Tab. 9 Ductility and response modification factors for each of the key parameters

No.

Variable parameter

Model

W37-F37

W52-F37

W37-F52

W52-F52

µ

R

µ

R

µ

R

µ

R

P50

C25

D00

10

16

12

15

12

13

8

9

P50

C35

D00

12

18

12

15

12

14

12

12

3

P50

C45

D00

15

21

12

15

12

14

12

13

4

P50

C25

D00

15

19

12

14

12

18

17

17

1 2

Compressive strength

P50

C25

D20

8

16

6

14

8

14

10

12

6

P50

C25

D35

2

2

1

1

5

9

7

2

7

P30

C25

D00

14

16

12

13

5

6

3

4

P40

C25

D00

16

17.5

12

14

5

6

3

4

P50

C25

D00

19

20

18

16

13

16

7

9

5

8

Gap width

Panel thickness

9

Fig. 16 Ductility ratio versus concrete panel thickness

Fig. 18 Shear capacity versus concrete compressive strength

Fig. 17 Response modification factor versus concrete panel thickness

Fig. 19 Initial stiffness versus concrete compressive strength

As presented in Figs. 18 and 19, the increase in concrete strength improves the shear capacity and initial stiffness.

Although Fig. 18 illustrates the comparison between the improvement rate of the shear capacity due to an increase in concrete strength, it was found that the shear capacity of W37-F37 improved by 150 % but, in contrast, W52-F52 experienced only a 15 % improvement. Accordingly, it is concluded that to provide a high shear capacity it would be rational to increase concrete strength.

increases, which might be due to the occurrence of buckling in the steel plate and, consequently, a reduction in the capacity. Moreover, a similar trend can be seen in Fig. 21, which demonstrates the effect of gap width on initial stiffness. Based on this figure, W37-F37 has been severely affected, with its stiffness decreasing by 23.8 and 28 %.

Fig. 20 illustrates the effect of an increase in gap width. As can be seen, the shear capacity decreases as the gap width

00_STCO_0121_Buch.indb 43

ARTICLE

A. Munesi, M. Sharbatdar, M. Gholhaki: An investigation into the factors influencing the cyclic behaviour of buckling-restrained steel plate shear walls

The trend in variation due to the effect of concrete panel thickness on shear capacity and stiffness is shown in Figs. 22 and 23. As expected, it can be seen that both para­meters, stiffness and capacity, have been enhanced as the panel has been thickened.

Steel Construction 14 (2021), No. 1 43

03.02.21 11:16

A. Munesi, M. Sharbatdar, M. Gholhaki: An investigation into the factors influencing the cyclic behaviour of buckling-restrained steel plate shear walls Tab. 10 Trend in variations in initial stiffness and capacity

No.

Variable parameter

Model

W37-F37

W52-F37

W37-F52

W52-F52

C [kN]

K C [kN/mm]

K

C

K

C

K

P50

C25

D00

2 000

333

2 200

370

2 600

500

3 200

520

P50

C35

D00

2 500

400

2 650

370

3 000

520

3 350

530

3

P50

C45

D00

3 000

500

3 170

480

3 480

540

3 700

540

4

P50

C25

D00

2 000

437.5

2 200

360

2 600

500

3 000

483

P50

C25

D20

2 000

333

2 200

360

2 000

450

2 700

416

6

P50

C25

D35

1 600

240

1 780

350

1 600

367

1 700

325

7

P30

C25

D00

2 200

500

2 600

360

2 300

733

2 470

383

P40

C25

D00

2 500

500

2 700

360

2 600

833

2 850

416

P50

C25

D00

3 000

550

3 150

360

2 800

900

3 250

500

1 2

5

8

Compressive strength

Gap width

Panel thickness

9

Fig. 20 Shear capacity versus gap width Fig. 22 Shear capacity versus concrete panel thickness

Fig. 21 Initial stiffness versus gap width

7 Conclusion This study presents the results of studying the effects of influencing factors involved in the behaviour of BRSPSW systems, with the aim being to obtain a better understanding of the design approach. The most notable conclusions are as follows: – Based on the comparison of the energy dissipation, it is concluded that increasing the concrete compressive strength does not affect energy dissipation significantly.

44

Fig. 23 Initial stiffness versus concrete panel thickness

Conversely, when using steel elements with a higher strength, energy dissipation markedly improved by up to 33 %. In this respect it was observed that as steel strength increases, so the rate of improvement in energy dissipation rises, with minimum and maximum rates of improvement equal to 0.7 and 11.7 % for W37-F37 and W52-F52 respectively. On this basis it can be suggested that in terms of energy dissipation, the bounda-

Steel Construction 14 (2021), No. 1

00_STCO_0121_Buch.indb 44

03.02.21 11:16

ry elements play a more effective role in contrast to the planar elements including steel plate and concrete panels.

– It was found that as the gap widens, so energy dissipation is enhanced correspondingly. Importantly, it was observed that an increase in gap width has to occur up to a certain limit because once this limit is exceeded, the rate of improvement in energy dissipation is reduced, which is attributed to the higher probability of buckling in the steel plate and, consequently, under­ mines the effect of the concrete panel.

– Thickening the concrete panels in W37-F37, W52-F37 and W52-F52 resulted in better energy dissipation.

Moreover, comparing the rate of improvement in the energy absorbed by W52-F37 and W37-F52, whose values are 324, 208 and 140 % for thicknesses of 30, 40 and 50 mm respectively, demonstrated that increasing the strength of the frame elements is followed by a reduction in ductility and, consequently, less energy being dissipated compared with the case of using steel with a lower strength. This conclusion proves the great importance of the boundary elements for the general behaviour of the system regarding energy absorption.

– Based on the results, an increase in compressive strength does not significantly affect the ductility, which is attributed to the direct relation between ductility and displacement and, finally, stiffness, which is not greatly influenced by concrete strength. In addi­ tion, the results indicate that the increase in com­ pressive strength improves the response modification factor.

– Widening the gap between concrete panel and steel plate decreases the response modification factor, which is due to the fact that the buckling phenomenon is expedited and, as a result, the system will ex­ hibit lower strengths.

– The results indicate that as concrete strength increases, so both shear capacity and initial stiffness rise accordingly. The comparison between the increase in strength of the concrete and steel elements reveals that the capacities of W37-F37 and W52-F52 im­prove by 150 and 115 % respectively. In this respect, it is concluded that to provide high shear capacities for the system, it would be rational to increase the con­crete strength.

ARTICLE

A. Munesi, M. Sharbatdar, M. Gholhaki: An investigation into the factors influencing the cyclic behaviour of buckling-restrained steel plate shear walls

References [1] Ericksen, J.; Sabelli, R. (2008) A Closer Look at Steel Plate Shear Walls in: Modern Steel Construction, pp. 63–67.

[2] Takahashi, Y.; Takamoto, Y.; Takeda, T.; et al. (1973) Experimental study on thin steel shear walls and particular bracing under alternative horizontal loading in: IABSE Symp. on Resistance & Ultimate Deformability of Structures Acted on by Well-defined Repeated Loads, Lisbon, Portugal, pp. 185–191.

[3] Thorburn, L. J.; Kulak, G. L.; Montgomery, C. L. (1983) Analysis of steel plate shear walls, Structural Engineering Report No. 107, Dept. of Civil Engineering, University of Alberta.

[4] Robert, T. M.; Sabouri-Ghomi, S. (1992) Hysteretic characteristics of unstiffened perforated steel plate shear panels in: Thin-Walled Struct. 14 , pp. 139–151.

[5] Caccese, V.; Elgaaly, M.; Chen, R. (1993) Experimental study of the thin steel-plate shear wall under cyclic load in: J. Struct. Eng. 119 (2), pp. 573–587.

[6] Zhao, Q.; Astaneh-Asl, A. (2004) Cyclic behavior of traditional and innovative composite shear walls in: J. Struct.

Eng. ASCE 130 (2), pp. 271–284.

[7] Guo, L.; Li, R.; Rong, Q.; et al. (2012) Cyclic behavior of SPSW and CSPSW in composite frame in: Thin-Walled Struct. 51, pp. 39–52.

[8] Astaneh-Asl, A. (2002) Seismic behavior and design of composite steel plate shear walls, Steel Tips Report, Structural Steel Educational Council, USA. [9] ANSI/AISC 341-10 (2010) Seismic provisions for structural steel buildings, American Institute of Steel Construction, Chicago.

[10] Zhao, Q.; Astaneh-Asl, A. (2007) Seismic behavior of composite shear wall systems and application of smart structures technology in: Steel Struct. 7, pp. 69–75.

[11] Qiuhong, Z.; Astaneh-Asl, A. (2004) Seismic behavior of composite shear wall systems and application of smart

00_STCO_0121_Buch.indb 45

structures technology in: 13th World Conf. on Earthquake Engineering, Vancouver, Paper No. 2578.

[12] Qiuhong, Z.; Astaneh-Asl, A. (2004) Cyclic behavior of traditional and innovative composite shear walls in: Journal of Steel Structures 130, No. 2, pp. 60–75.

[13] Arabzadeh, A.; Soltani, M.; Ayazi, A. (2011) Experimental investigation of composite shear walls under shear loadings in: Thin-Walled Struct. 49, pp. 842–854.

[14] Rasouli, B.; Shafaei, S.; Ayazi, A.; Farahbod, F. (2016) Experimental and Numerical study on steel-concrete composite shear wall using light-weight concrete in: J. Constr. Steel Res. 126, pp. 117–128.

[15] Li, X.; Li, X. (2017) Steel Plates and Concrete-Filled Composite Shear Walls related Nuclear Structural Engineering: Experimental Study for Out-of-Plane Cyclic Loading in: Nuclear Engineering and Design, 315, pp. 144–154.

[16] Shafaei, S.; Ayazi, A.; Farahbod, F. (2016) The effect of concrete panel thickness upon composite steel plate shear walls in: J. Constr. Steel Res. 117, pp. 81–90.

[17] Shafaei, S.; Ayazi, A.; Farahbod, F. (2017) Concrete Stiffened Steel Plate Shear Walls with an Unstiffened Opening in: Structures, https://doi.org/10.1016/j.istruc.2017.07.004.

[18] Meghdadian, M.; Ghalehnovi, M. (2019) Improving Seismic Performance of Composite Steel Plate Shear Walls containing Openings, Journal of Building Engineering, https://doi. org/10.1016/j.jobe.2018.11.001.

[19] Pachideh, G.; Gholhaki, M.; Yadegari, A. (2016) Modeling and Analysis of Thin Steel Plate Shear Walls using the New Method in: 2nd Intl. Conf. on Civil Engineering, Architecture & Urban Planning Elites, 15 Nov 2016, London [20] Gholhaki, M.; Pachideh, G. (2015) Investigating of Damage Indexes Results Due to Presence of Shear Wall in Building with Various Stories and Spans in: Int J Rev Life Sci 5 (1), pp. 992–997.

Steel Construction 14 (2021), No. 1 45

03.02.21 11:16

A. Munesi, M. Sharbatdar, M. Gholhaki: An investigation into the factors influencing the cyclic behaviour of buckling-restrained steel plate shear walls

[21] Yadegari, A.; Pachideh, G.; Gholhaki, M.; Shiri, M. (2016) Seismic Performance of CSPSW in: 2nd Intl. Conf. on Civil Engineering, Architecture & Urban Planning Elites, 15 Nov 2016, London.

[22] Pachideh, G.; Gholhaki, M.; Daryan, A .S. (2019) Analyzing the damage index of steel plate shear walls using pushover analysis in: Structures 20, pp. 437–451, https://doi.org/­ 10.1016/j.istruc.2019.05.005.

[23] Afshari, M. J.; Gholhaki, M. (2018) Shear strength degradation of steel plate shear walls with optional located opening in: Archives of Civil & Mechanical Engineering 18, No. 4, pp. 1547–1561, https://doi.org/10.1016/j.acme.2018.06.012.

[24] Gholhaki, M.; Karimi, M.; Pachideh, G. (2019) Investigation of Subpanel Size Effect on Behavior Factor of Stiffened Steel Plate Shear Wall in: Journal of Structural & Construction Engineering 5, Special issue 4, serial No. 21, Winter 2019, pp. 73–87.

[25] Gholhaki, M.; Pachideh, G.; Rezayfar, O.; Ghazvini, S. (2019) Specification of Response modification factor for Steel Plate Shear Wall by Incremental Dynamic Analysis Method in: Journal of Structural & Construction Engineering 6, special issue 2, serial No. 25, Autumn 2019, pp. 211 224.

[26] ABAQUS/Explicit User’s Manual, version 6.1, Hibbitt, Karlsson, Sorensen, Inc., (HKS), 2010.

Authors Ali Munesi, PhD candidate munesiali@yahoo.com Dept. of Civil Engineering, Semnan University Semnan, Iran

How to Cite this Paper

Mohammadkazem Sharbatdar, Associate Professor (corresponding author) msharbatdar@semnan.ac.ir Dept. of Civil Engineering, Semnan University Semnan, Iran

This paper has been peer reviewed. Submitted: 31. October 2019; accepted: 1. May 2020.

Munesi, A.; Sharbatdar, M.; Gholhaki, M. (2021) An investigation into the factors influencing the cyclic behaviour of buckling-restrained steel plate shear walls. Steel Construction 14, No. 1, pp. 35–46. https://doi.org/10.1002/stco.201900047

Majid Gholhaki, Associate Professor mgholhaki@semnan.ac.ir Dept. of Civil Engineering, Semnan University Semnan, Iran

Bert Snijder, Henri Steenbergen

Structural basics Steel Design 1

Analysis and design of steel structures for buildings according to Eurocode 0, 1 and 3

Steel Design 1

 basics

of steel construction according to Eurocodes  major topics from actions to code-checking covered  result of long teaching experience

H.H. Snijder H.M.G.M. Steenbergen

Structural basics

The book is a well-illustrated, easy introduction to steel structures for buildings according to the Eurocodes. It covers structural safety and common load assumptions, modelling and material properties, major analysis methods as well as code-based design.

2020 · 271 pages · 219 figures · 39 tables ebook ISBN 978-3-433-61069-5

€ 49,99*

ORDER +49 (0)30 470 31–236 marketing@ernst-und-sohn.de www.ernst-und-sohn.de/en/steel-design 46

Steel Construction 14 (2021), No. 1 * All book prices inclusive VAT.

1283.indd 15 00_STCO_0121_Buch.indb 46

8/2020

04.08.2020 10:30:34 03.02.21 11:16

Komal Rajana, Andrés Alonso-Rodríguez, Konstantinos Daniel Tsavdaridis

ARTICLE

ARTICLE

DOI: 10.1002/stco.202000043

A wavelet-based approach for describing the mechanical behaviour of cellular beams This paper describes how a wavelet model comprised of a linear combination of sine terms is capable of representing the cross-section inertia variation along the length of cellular beams. This allows the efficient computation of deflections of cellular beams when these are deployed as a part of steelconcrete composite flooring systems. This method does not involve purely statistical approaches or piece-wise integration of moment-curvature relationships that lead to cumbersome matrix approaches and complicate the assessment of deflections. Despite its simplicity, the proposed approach is found to be reliable as it successfully predicts displacements obtained through finite element model representations of more than 260 cases with errors smaller than ±5 %. Furthermore, the proposed analytical description of cross-section inertia along the beam length is defined by only three parameters that can be inferred through linear expressions considering the geometrical characteristics of a perforated beam, namely, the ratio of flange to web thickness, the second moment of inertia of the steel beam and the ratio between beam length and depth, making it easy for widespread application by practitioners.

Keywords cellular beams; perforated beams; variable inertia; wavelets; structural steel design

1 Introduction Sustainable development is becoming a major concern worldwide, leading to a re-evaluation of current practices to ensure that current needs do not compromise the wellbeing of future generations [1]. In particular, a new development, the Doughnut framework, is becoming mainstream [2]. It calls for the implementation of industrial processes that limit the consumption of energy and resources within a band that effectively satisfies basic needs for a comfortable life without depleting the environment’s replenishment capability, and requires a highly optimal use of basic goods [3].

Steel construction has a high adverse environmental impact, as the production of new structural steel has been estimated to produce 1.85 t of equivalent CO2 per tonne of structural steel. This makes the steel industry responsible for 8 % of the total CO2 emissions related to the use of fossil fuels worldwide according to the World Steel Association [4]. Even if extensive recycling is implemented, the challenge ahead is daunting, as a large investment in infrastructure, estimated at between USD 7 and 9 trillion, needs to be allocated by 2040 [5]. Consequently, current practices would lead to a disproportionate impact on the

00_STCO_0121_Buch.indb 47

natural environment which would make the development of new infrastructure non-sustainable.

These figures call for more efficient use of structural steel in the construction industry. One interesting approach is the use of perforated steel beams that use less material and minimize the self-weight of structures. Furthermore, openings in girders and beams facilitate other construction tasks, particularly the installation of ventilation ducts, electricity cables and data networks, thus leading to further savings of resources and time. It has also been observed that the widespread use of perforated beams allows longer spans, which leads to airier, light-filled spaces that require fewer structural columns, making their deployment even more sustainable and cost-rational.

The design of perforated steel beams is more challenging than procedures for beams without openings, as several intricate behavioural patterns are introduced by creating openings in the web region. The discontinuities in the beam web compromise the validity of Euler’s plane theory [6] and lead to localized failure modes such as flange buckling and torsion as well as large section warping [7].

This prevents the stable achievement of substantial plastification of the cross-section and results in significant de­gradation of potential structural capacity. However, most of these issues have been addressed by research to some extent, leading to perforated beam designs that are cost-efficient and capable of reaching a structural capacity comparable to their unperforated counterparts [8, 9].

Several perforation shapes have been assessed, among them circular [10], hexagonal and octagonal [7, 11], elliptical [12] and topologically optimized [13]; even the use perforated H-beams has been explored [14], while Tsavdaridis and Galiatsatos [15] have addressed the issue of the optimal placing of stiffeners. Most recently, the trend in research and development concerning cellular beams has been towards reducing the overall depth of floor systems. This has led to diverse solutions, among them: Ultra Shallow Floor Beams (USFB) [16], where the top flange at least is completely encased within the concrete slab, Composite Slim Floor Beams (CoSFB), which fit hollow core planks between flanges [17], and Delta Composite Beams, which consider a perforated prismatic element with a trapezoidal cross-section. The openings in the latter system allow for continuity of reinforcement, if fully enclosed, or building services if only the top flange is embedded, making them convenient while achieving a notable fire-resistant behaviour [18].

Despite these research outcomes, current established

© 2020 Ernst & Sohn Verlag für Architektur und technische Wissenschaften GmbH & Co. KG, Berlin. Steel Construction 14 (2021), No. 1 47

03.02.21 11:16

K. Rajana, A. Alonso-Rodríguez, K. D. Tsavdaridis: A wavelet-based approach for describing the mechanical behaviour of cellular beams

design guidelines still underestimate the structural capacity of most widely used configurations of perforated beams by at least 15 %, sometimes by as much as 40 % [19]. This reveals the need to develop tools that facilitate widespread adoption.

In addition, web openings reduce the cross-section stiffness in a non-linear fashion along the beam length. Thus, it is expected that perforated beams will experience larger deflections than beams without openings for the same loads [20]. This issue can become critical for the design, as it compromises their function under serviceability conditions [21] due to fatigue and damage to non-structural elements, which have a deformation capacity in the elastic or nearly-elastic range which is less than a fifth of that observed for structural components [22, 23].

Therefore, engineering practice has been pressing for re­ liable methods of assessing the deflections of perforated beams. Pioneering research on the topic was carried out in the 1970s [24]. The most common approach for addressing this issue is through direct integration of loaddeflection relationships or the use of the virtual work method [25–29] considering discontinuous functions.

This leads to the formulation of matrices that must be solved for each particular case, which in turn leads to a proto-finite element model formulation that must be coupled with the general model of the whole structure for concise finite element model analyses. This level of complexity and lack of a way to establish general rules for the quick design of floor systems, which is usually done separately from the assessment of the frame resisting lateral loads, has not been widely applied by practitioners. Another approach for developing reliable methods of assessing deflections is to perform regression analyses on the results of finite element models [30], which can be easily applied to several cases. However, as relationships are statistical, the fundamental processes leading to them are obscured.

This paper aims to explore analytical expressions that are capable of describing the stiffness variation along the length which is observed in composite-perforated beams.

For that purpose, periodic expressions are need which are defined in non-dimensional scales, with wavelets being a prime candidate [31]. Furthermore, wavelets have been extensively used in signal analysis for filtering and signal compression [32], meaning that engineers are familiar with them. Therefore, this study modifies the MavoreidisPapageorgiou (MP) wavelet [33] for representing the variation of flexural inertia along the length of a beam with circular, evenly spaced openings, which are observed to have the best structural performance. This configuration leads to stable collapse mechanisms with a large deformation capacity that involves the development of four plastic hinges around the openings [8, 9]. The proposed function is a linear combination of sine functions which involves, at most, four parameters that can be inferred directly from the geometry of the beam. Therefore, deflections along the beam can be found analytically through 48

direct integration of moment-curvature relationships if the moment diagram is known. This approach has been benchmarked by finding the set of parameters that minimizes the squared difference between deflections predicted by the proposed stiffness variation and the results of finite elements, focusing on locations centred on midspan and spreading two-thirds of the beam length from it in both directions. The results indicate that relative deflection errors are less than 5 % for more than 99 % of all samples. As a consequence, the proposed stiffness variation is capable of providing insights into the expected deflections of flooring systems, which are usually simply supported on girders. Finally, reliable regression equations are provided, relating the beam geometry to parameters describing the stiffness variation of the beam, thus allowing easy use by practitioners.

2

Deflections of simply supported cellular beams with variable inertia

Euler’s plane section hypothesis leads to a direct relationship between moment demands, flexural inertia and deflection [34].

( ) = d 2u (1) EI ( x ) dx2 M x

where M(x) is the moment demand at ordinate x along the beam, E is the Young’s modulus and u is the deflection. For simply supported beams, M(x) is given by

()

M x =

wL wx2 x− (2) 2 2

Boundary conditions for a simply supported beam require that the deflection is zero at its extremes (x = 0 and x = L).

After integrating Eq. (1) twice and incorporating these conditions, the deflection is given by



M( x) dx −  ∫ ( ) ∫∫ EI ( x)  0

u x =

L

M( x)  dx x (3) EI( x) 

The flexural inertia can be alternatively expressed as

()

()

I ξ = EI0 S ξ (4)

After substituting Eq. (2) into Eq. (4) and introducing the additional normalizing variable x, Eq. (3) becomes

()

u ξ =

wL4   2 EI0  

∫∫

 ξ − ξ2 dξ −  S(ξ ) 

  − ξ2 dξ  ξ  (5) S(ξ )  

1ξ

∫0

The variable x takes values between 0 and 1, and S(x) should have an oscillatory behaviour capable of representing the effect of the cross-section’s changing inertia.

Similarly, the proposed model should scale well with length, being versatile enough to accommodate a varying number of perforations. Wavelets are well suited to these purposes.

Steel Construction 14 (2021), No. 1

00_STCO_0121_Buch.indb 48

03.02.21 11:16

One of the most versatile wavelet models available is the MP acceleration pulse [33]. Recently, it was shown that it can be represented as the sum of three sine terms, making it differentiable and integrable to any order [35]. How­ ever, the function defining it cannot take negative values, compromising its suitability to represent S(x ) in its basic form. In this study the MP pulse model has been tailored to fit the requirements of flexural stiffness variations in beams, leading to the following expression:

(

)

S ξ , Ae ,κ , γ =   γ + 1  sin  2π γ + 1 ξ − πγ         2γ     γ − 1  Ae − κ +  sin  2π γ − 1 ξ − πγ   ; 0 ≤ ξ ≤ 1 (6)      2γ   − sin 2πγξ − πγ     

(

2

(

)

)

(

)

where Ae, k and g are parameters that have been observed in this study to depend on the geometry of the cellular beam, namely, its length, its flange and web thicknesses and the gross inertia of the cross-section EI0. Fig. 1 shows plausible trends for S(x, Ae,k, g ) that have been observed for certain beam configurations considered in this study.

3 Methodology Firstly, a set of benchmarking test cases was formulated which considers typical layouts for flooring systems expected in residential and light retail properties. The base

model consists of I-beams 500 mm deep × 200 mm wide supporting a 100 mm deep concrete slab. This arrangement is subjected to a load of 50 kN/m. The layout of the benchmark cases follows the following limits on ratios between web depth, opening diameter and perforation c/c spacing, according to design guidelines [7]:

1.25 <

Hw < 1.75 (7) Do

1.08 <

S o < 1.5 (8) D o

ARTICLE

K. Rajana, A. Alonso-Rodríguez, K. D. Tsavdaridis: A wavelet-based approach for describing the mechanical behaviour of cellular beams

The thresholds defined in Eqs. (8) and (9) will prevent unexpected buckling and torsion of the web. Similarly, the first opening is at a distance greater than one half of its diameter from each end of the beam, to prevent crushing due to the reactions at the ends.

The following variations were then imposed on the base model: 1) beam lengths ranging from 2.2 to 6.8 m, 2) concrete slab widths equivalent to one quarter of the beam length, to account for composite action with the steel beam, following design recommendations [7], 3) flange and web thicknesses of 10, 15 and 20 mm, considering all their possible combinations, and 4) hole spacings of 23, 27, 33, 116 and 200 mm.

The first three cases were grouped as closely spaced perforations, whereas the latter two were denoted as average

Fig. 1 Examples of S: Ae = 1.3, k = 0.3, g = 5 on left; Ae = 0.5, k = 0.25, g = 5 on right

Fig. 2 Geometrical layout of test cases considered

00_STCO_0121_Buch.indb 49

Steel Construction 14 (2021), No. 1 49

03.02.21 11:16

K. Rajana, A. Alonso-Rodríguez, K. D. Tsavdaridis: A wavelet-based approach for describing the mechanical behaviour of cellular beams

Fig. 3 Overall view of FEM model: a) displacements, and b) Von Mises stresses as observed for the following test case: L = 5 000 mm, tf = 10 mm, tw = 10 mm, Hw = 500 mm, Do = 400 mm, WP = 200 mm, tc = 100 mm, bc = 1 000mm

and widely spaced perforations. A total of 267 test cases was defined, and they are summarized in the appendix (Tab. A1). A general layout of the geometrical characteristics of the specimens is presented in Fig. 2.

The behaviour of the test cases was assessed using the finite element method (FEM) implemented in Abaqus© [36] employing hexahedral, eight-node shell elements for both the concrete slab and the steel beam. The elements had an aspect ratio < 2 and a largest dimension < hw/20 for elements placed between openings, following ElSawhi et al. [37]. This arrangement has been observed to describe accurately the observed behaviour of composite beams during laboratory tests [38, 9] while leading to an efficient computational implementation [39]. Fig. 3 shows the FEM model.

An elastic, isotropic constitutive model was employed to represent both materials: unconfined concrete and structural steel. This is a suitable choice, as deflections during operation are of interest. The following elastic parameters were considered for its definition: Young’s modulus of steel = 200 GPa; Young’s modulus of concrete = 31 GPa, in accordance with Eurocode 2 [40]; Poisson’s ratio for steel = 0.3; Poisson’s ratio for concrete = 0.2.

The boundary conditions are presented in Fig. 4. Out-ofplane displacements at the supports were constrained by restricting displacements at the four corners of the beam ends, while allowing in-plane rotations. Axial displacements were restricted at the left-hand support, but permitted at the right-hand support, representing simple and roller supports respectively.

50

Fig. 4 Boundary conditions: a) left-hand support, and b) right-hand support

Fig. 5 Histogram of relative errors

Computation of analytical deflections according to Eq. (5) was done numerically considering the trapezoidal rule [41] for a given set of parameters, thus allowing the evaluation of relative errors between them and values found through FEM analyses, as shown by Eq. (9):

E=

∑

2

 u  1 − ai  (9)  i=1 uFemi  

N

Steel Construction 14 (2021), No. 1

00_STCO_0121_Buch.indb 50

03.02.21 11:16

where uai is the analytical deflections at the ith sampling location for a given test case and ufemi is the deflection according to the FEM model at the same place. The summation is performed across all sampling locations for a particular test case.

It is then possible to find the set of parameters for the proposed stiffness variation – namely, g, k and Ae – that would lead to minimum values for E in Eq. (9) for each case. This is done by applying the Mathcad implementation of the KNITRO algorithm [42].

4 Results A total of 98 % of observed errors among 1 096 deflection samples range between –5 and +5 %. Moreover, the 25–75 % interquartile range was observed for errors ranging between –1 and +1 %. The mean, median and mode values are –0.06, +0.06 and +0.07 % respectively, revealing how estimates are practically unbiased. Still, differences among these values show a slight skewness towards negative errors. In overall terms, the results are reliable enough to assess deflections under service conditions.

The g parameter in Eq. (6) determines the oscillatory characteristics of the wavelet model [43]. In particular, it takes a value of one half of the number of openings in the cellular beams Np, setting the number of peaks of S(x) along the beam length.

γ =

Np 2

(10)

Multivariate regression analyses allow prediction equations to be defined for the remaining stiffness parameters Ae and k in terms of the geometrical characteristics of cellular beams. Specifically, it has been observed that beam length, flange and web thicknesses and perforation spacing are the most relevant parameters for defining the stiffness variation pattern. In particular, the following expressions were found:

κ = 0.0634 − 0.0268 + 0.0091

I Tf − 1.1935 o3 (11) Tu bh

L + SWP h

Tab. 1 SWP values for beams with close and large stiffener widths

Spacing

k

Ae

Close (< 40 mm)

0.2478

0.0022

Large (> 200 mm)

–0.2208

0.2589

Together, both expressions provide a reliable way of defining the stiffness variation along the length of perforated beams, as their adjusted coefficients of determination reach 0.836 for Eq. (11) and 0.875 for Eq. (12), making their use well suited to design.

5

Ae = 0.4033 + 2.009κ − 0.1396 − 1.6534

Io bh

3

+ 0.0566

Tf Tu

(12)

L + SWP h

where SWP is a constant that takes different values depending on the narrowest width between perforations WP, as shown in Fig. 2. Three categories have been defined for this variable: close, for WP values < 40 mm; average, for WP values between 100 and 120 mm; large, for WP values > 200 mm. The value of SWP is zero for beams with an average spacing, while for the other categories it takes the values presented in Tab. 1.

00_STCO_0121_Buch.indb 51

Worked example

This example presents the design of an interior girder on the second floor of a three-level retail commercial centre that has a high-traffic, terrazzo floor finish. Girders are uniformly spaced at 6 m in both directions (NS-EW). As the girder will not be part of the lateral load support system, it will be simply supported on its framing columns.

The design will be performed in accordance with Euro­ code 2 [7] guidelines, while loads will be as prescribed by the ASCE SEI 7 [44] specifications, considering a girder spacing of 6 m. This leads to the design actions stated in Tab. 2.

Loads are supported by a 500 mm deep × 200 mm wide 50 kSI (345 N/mm2) steel I-beam that has flange and web thicknesses of 10 mm – values that make the section compact for flexure [7]. The beam supports an f′c = 35 N/mm2 nominal-strength 100 mm deep concrete slab provided with shear connectors to ensure combined deformation of the slab and the beam. The required moment demand is

Mu =

Wu L2 80 × 36 = = 360 kNm (13) 8 8

The structural design will follow a simplified approach.

Owing to the perforations, it is assumed that only the bottom flange will contribute to the moment capacity of the cross-section. If that is the case, the maximum tensile load that can be sustained is

ARTICLE

K. Rajana, A. Alonso-Rodríguez, K. D. Tsavdaridis: A wavelet-based approach for describing the mechanical behaviour of cellular beams

T = As ⋅ fy = b ⋅ tf ⋅ fy =

200 × 10 × 345 = 690 kN (14) 1000

where As is the area of the bottom flange, b the beam width, tf the bottom flange thickness and fy the steel yield stress (345 N/mm2). Consequently, the depth of the Tab. 2 Design actions considered in the example

Design action

Value [kN/m]

Dead load WD Live load WL Ultimate design load, Wu = 1.2WD + 1.6WL Service condition load, WS = WD + WL

37 22 80 65

Steel Construction 14 (2021), No. 1 51

03.02.21 11:16

K. Rajana, A. Alonso-Rodríguez, K. D. Tsavdaridis: A wavelet-based approach for describing the mechanical behaviour of cellular beams

equivalent Witney’s compressive block from the uppermost fibre of the slab is given by [45]

a=

690 000 T = = 16 mm (15) 0.85 ⋅ be ⋅ f 'c 0.85 × 1 500 × 28

where be is the equivalent width of the concrete slab, taken to be one quarter of its length [7], and f′c is the nominal strength of the concrete. Finally, the factored, nominal capacity of the cross-section where the perforations are largest is at least

 t c ∅Mn = ∅  d − f + e −  (16) 2 2  690 × 500 − 5 + 100 − 8 = 0.9 = 364 kNm 1000

(

)

The shear capacity of the steel beam, neglecting any contribution by the slab, is

∅Vn = ∅0.6 As fy = ∅ ⋅ h ⋅ tw ⋅ fy =

(17)

Fig. 6 Stiffness variation obtained for the example

thus providing an allowance for a connection plate for the beam. In total, 16 perforations can be made through the entire length of the beam, leading to g = 8. Consequently, the stiffness variation along the beam length is given by

0.9 × 0.6 × 500 × 10 × 345 = 931 kN 1000

2

(

while the shear demand at the support is

Vu =

wu L 80 × 6 = = 240 kN (18) 2 2

Thus, the shear capacity of the steel section is greater than 3.5 times the expected demand, while it provides just enough moment resistance, making it optimal.

The second step is the assessment of expected deflections.

Firstly, the second moment of inertia of the steel beam without perforations must be computed. In this example it is 3.481 × 108 mm4. Considering the high shear overstrength available, closely spaced openings will be considered. Then, according to Eqs. (11) and (12) the Ae value expected for the proposed section are

κ = 0.0634 − 0.0268 + 0.0091

10 3.481 × 108 − 1.1935 (19) 10 200 × 5003

6 000 + 0.2478 = 0.38 500

10 (20) 10 8 3.481 × 10 6 000 + 0.0566 + 0.0022 −1.6534 500 200 × 5003 = 1.70

Ae = 0.4033 + 2.009 × 0.38 − 0.1396

Perforations with a diameter of 320 mm are considered; the ratio Hw/D0 becomes 1.56, which is within the range specified by Eq. (7). Similarly, a spacing of 300 mm bet­ ween perforations leads to a ratio Sd/D0 = 1.09, also within the boundaries stated in Eq. (8). This is also within what is considered a close spacing in this study. The first and last perforations will be 215 mm from each support, which is larger than the one-half diameter threshold that will prevent crushing due to the reaction (Do/2 = 160 mm), 52

   9 sin π 3x − 8      16   7     7 S x = 1.70 − 0.38 + sin π  x − 8   ; (21)      3  16   8   − sin π  x − 8         3

)

()

0≤x≤6 where x is the beam coordinate in metres from the support. The stiffness variability obtained is depicted in Fig. 4. The mid-span deflection expected under service conditions can be obtained after evaluating the integrals in Eq. (5), considering the proposed stiffness variation and the serviceability load of 65 kN/m, resulting in a value x = 18 mm. That is in accordance with AISC-16 [7], which sets a threshold of 1/300 of the span, which in this example is 20 mm.

6 Conclusions This study proposes an analytical function for describing the inertia variation along the length of steel-concrete composite cellular beams. It considers a squared sum of trigonometric terms that allows for an oscillatory value of inertia that decreases when the cross-section is reduced due to the presence of openings, and then increases again when they are absent at the web-post area. The suitability of the proposed approach was verified by comparing the results of deflections assessed analytically with results of more than 260 cases with various lengths, hole spacings and web and flange thicknesses. Among more than 1 000 locations where deflection was investigated, it was observed than in more than 98 % of those locations, the range is below 5 %; while in the great majority (80 %) the range is between –3 and +2.5 %. Consequently, the pro-

Steel Construction 14 (2021), No. 1

00_STCO_0121_Buch.indb 52

03.02.21 11:16

posed function is well suited to describing the deflection of composite cellular beams under service conditions.

Furthermore, regression analyses performed on para­ meters that best describe this stiffness variation pattern found allow a direct link to the geometrical characteristics of steel-concrete composite perforated beams, with the most critical being the number of openings, the ratio between flange and web thickness and the inertia of the gross steel section. The relationships obtained offer practitioners reliability, as more than 80 % of the variability can be explained by the proposed statistical models.

variation of steel-concrete composite perforated beams along their length by a simple mathematical expression that can be straightforwardly implemented in any structural analysis software. It is expected that this outcome will contribute to boosting confidence when using composite and non-composite perforated beams, as it improves the understanding of their deformation characteristics without requiring the use of detailed finite element models or matrix formulations. Therefore, this study makes a significant contribution to making steel construction more sustainable by promoting a lower weight per capita solution that makes better use of the materials provided.

ARTICLE

K. Rajana, A. Alonso-Rodríguez, K. D. Tsavdaridis: A wavelet-based approach for describing the mechanical behaviour of cellular beams

Thus, this approach provides a valuable tool for practitioners, as it makes it feasible to represent the stiffness

References [1] United Nations (1987) Report of the world commission on environment and development: our shared future. Report A/42/427, General Assembly UN. New York.

[2] Boffey, D. (2020) Amsterdam to embrace ‘doughnut’ model to mend post-coronavirus economy. The Guardian, 8 Ap 2020.

[3] Raworth, K. (2017) Doughnut Economics: Seven ways to think like a 21st century economist. Chelsea Green Publishing, Chelsea VT. [4] World Steel Association (2020) Steel’s contribution to a low carbon future and climate resilient societies. World Steel Association, Brussels, Belgium.

[5] Oxford Economics (2017) Global Infrastructure Outlook.

Global Infrastructure Hub. Sydney, Australia.

[6] Benitez, M. A.; Darwin, D.; Donahey, R. C. (1998). Deflections of composite beams with web openings in: Journal of Structural Engineering 124(10), pp. 1139–1147.

[7] American Institute of Steel Construction, AISC (2016) Specifications for structural steel buildings. AISC 360, Chicago, Ill. [8] Chung, K. F.; Liu, T. C. H.; Ko, A. C. H. (2000) Investigation on Vierendeel mechanism in steel beams with circular web openings in: Journal of Constructional Steel Research 57, pp. 467–490 [9] Tsavdaridis, K.; D’Mello, C. (2009) Web buckling study of the behaviour and strength of perforated steel beams with different novel web opening shapes in: J. Constr. Steel Res. 67, pp. 1605–1620 [10] Erdal, F.; Saka, M. (2013) Ultimate load carrying capacity of optimally design steel cellular beams in: Journal of Constructional Steel Research 80, pp. 355–368 [11] Wang, P.; Kangrui, G.; Zhang, L. (2016) Shear buckling of web-post in a castellated steel beam with hexagonal web openings in: J. Constr. Steel Res 121, pp. 173–184 [12] Tsavdaridis, K.; D’Melo, C. (2012) Optimization of novelelliptically-based web openings shapes of perforated steel beams in: J. Constr. Steel Res 76, pp. 39–53 [13] Tsavdaridis, K.; Kingman, J.; Toropov, V. (2015) Application of structural topology optimisation to perforated steel beams in: Computers and structures 158, pp. 108–123 [14] Feng, R.; Zhan, H.; Meng, S.; Zhi, J. (2018) Experiments on H-shaped strength steel beams with perforated web in: Engineering structures 177, 3 pp. 74–394.

[15] Tsavdaridis, K.; Galiatsatos, G. (2015) Assessments of cellular beams with transverse stiffners an closely spaced web openings in: Thin-walled structures 94, pp. 636–650.

00_STCO_0121_Buch.indb 53

[16] Tsavdaridis, K.; D’Mello, C.; Huo, B. (2013). Experimental and computational study of the vertical shear behaviour of partially encased perforated steel beams in: Engineering structures 56, pp. 805–822.

[17] Ahmed, I.; Tsavdaridis, K. (2018) Life cycle assessment (LCA) and cost (LCC) studies of lightweight composite flooring systems in: Journal of Building Engineering 20, pp. 624–633.

[18] Maraveas, C. (2017) Fire resistance of DELTABEAM® composite beams: a numerical investigation in: Journal of Structural Fire Engineering 8(4), pp. 338–353.

[19] Akrami, V.; Erfani, S. (2016) Review and assessment of design methodologies for perforated steel beams in: Journal of Structural Engineering 142(2), pp. 1–14.

[20] Sonck, D.; Kinget, L.; Belis, J. (2015) Deflections of cellular and castellated beams. International Association for Shell & Spatial Structures Symposium, 17–20 Aug 2015, Amsterdam, Netherlands.

[21] Lawson, R. M.; Hicks, S. J. (2011) Design of composite beams with large openings. SCI P355. Steel Construction Institute, Berkshire, UK. [22] Charleson, A (2007) Architectural design for earthquake, a guide to the design of non-structural elements. New Zealand society for earthquake engineering, Wellington.

[23] Magenes, G.; Modena, C.; Da Porto, F.; Morandi, P. (2009) Behavior and design of new masonry buildings: recent developments and consequent effects of design codes in: Euro­ code 8 perspectives from the Italian perspective workshop.

Doppiavoice, Napoli, pp. 199–212.

[24] Dougherty, B. K. (1980) Elastic deformation of beams with web opening in: Journal of the Structural Division, ASCE 106(1), pp. 301–312.

[25] Donahey, R. C.; Darwin, D. (1986) Performance and design of composite beams with web openings. AISC Research project 21.82, American Institute of Steel Construction.

[26] Darwin, D. (1990) Steel and composite beams with web openings. AISC Design Guides, American Institute of Steel Construction.

[27] Ward, J. K. (1990) Design of composite and non-composite cellular beams. SCI P100. Steel Construction Institute, Berkshire UK. [28] Muller, C.; Hechler, O.; Bureau, A.; Bitar, D.; Joyeux, D.; Cajot, L. G.; Demarco, T.; Lawson, R. M.; Hicks, S.; Devine, P.; Lagerqvist, O.; Hedmann-Petursson, E.; Unosson, E.; Feld-

Steel Construction 14 (2021), No. 1 53

03.02.21 11:16

K. Rajana, A. Alonso-Rodríguez, K. D. Tsavdaridis: A wavelet-based approach for describing the mechanical behaviour of cellular beams

mann, M. (2006) Large web openings for service integration in composite floors. European Communities, Luxembourg.

[29] Zhou, D.; Li, L.; Schnell, J.; Kurz, W.; Wang, P. (2012) Elastic deflections of simply supported steel I-beams with a web opening in: Procedia Engineering 31, pp. 315–323.

[30] Panedpojaman, P.; Thepchatri, T. (2013) Finite element investigation on deflection of cellular beams with various configurations in: International Journal of Steel Structures 13(3), pp. 487–494.

[31] Daubechies, I. (1992) Ten lectures on wavelets. SIAM: Society for Industrial and Applied Mathematics. Philadelphia, PA. [32] Goodman, R. (2006) Discrete Fourier and wavelet transforms: an introduction through linear algebra with applications to signal processing. WSPC World Scientific, Singapore.

[33] Makris, N.; Vassiliou, M. (2011) Estimating time scales and length scales in pulselike earthquake acceleration records with wavelet analysis in: Bulletin of the Seismological Society of America. 101(2), pp. 596–618.

[34] Hibbeler, R. (2016) Mechanics of materials, 10th ed., Pearson. London, UK. [35] Alonso-Rodriguez, A.; Miranda, E. (2015) Assessment of building behavior under near-fault pulse-like ground motions through simplified models in: Soil Dynamics and Earthquake Engineering 79, pp. 47–58.

[36] Smith, M. (2009) Abaqus/standard user’s manual, ed. 6.9.

Dassault Systèmes Simulia Corp, Providence, RI.

Authors Komal Rajana komal_rajana@hotmail.com City University of London School of Mathematics, Computer Science & Engineering Northampton Square London EC1V 0HB, UK

Dr. Andrés Alonso-Rodríguez (corresponding author) andalon@gmail.com Technical Director Dideco Andean Region Cr 15 # 73-68 Bogotá, Colombia Dr. Konstantinos Daniel Tsavdaridis K.Tsavdaridis@leeds.ac.uk Associate Professor University of Leeds School of Civil Engineering Faculty of Engineering & Physical Sciences Woodhouse Lane, West Yorkshire Leeds LS2 9DY, UK

How to Cite this Paper Rajana, K.; Alonso-Rodríguez, A.; Tsavdaridis, K. D. (2021) A waveletbased approach for describing the mechanical behaviour of cellular beams. Steel Construction 14, No. 1, pp. 47–54. https://doi.org/10.1002/stco.202000043 This paper has been peer reviewed. Submitted: 13. June 2020; accepted: 17. August 2020.

54

[37] El-Sawhy, K. L.; Sweedan, A. M. I.; Martini, M. I. (2014) Moment gradient factor of cellular steel beams under inelastic flexure in: J. Constr. Steel Res. 98, pp. 20–34.

[38] Surtees, J. O.; Lui, Z. (1995) Report of Loading Tests on Cellform Beams. University of Leeds: Leeds, UK. [39] Abambres, M.; Rajana, K.; Tsavdaridis, K.; Ribeiro, T. (2018) Neural Network-Based Formula for the Buckling Load Prediction of I-Section Cellular Steel Beams in: Computers 8(1), p. 2.

[40] European Committee for Standardization CEN (2002) Euro­code 2: design of concrete structures – Part 1-1: general rules and rules for buildings. Brussels, Belgium.

[41] Kreyszig, E. (2017) Advanced engineering mathematics, 10th ed., Wiley, Hoboken NJ, USA. [42] Byrd, R.; Nocedal, J.; Waltz, R. (2006) Knitro: an integrated package for non-linear optimization in: Di Pillo G.; Roma M. (eds) Large-Scale Nonlinear Optimization. Nonconvex Optimization and Its Applications. Springer: Boston, pp. 35–59.

[43] Mavroeidis, G.; Papageorgiou, A. S. (2003) A mathematical representation of near-fault ground motions in: Bulletin of the Seismological Society of America 93(3), pp. 1099–1131.

[44] American Society of Civil Engineers (2016) Minimum design loads for buildings and other structures. ASCE, 3rd ed., Reston, VA. [45] Darwin D.; Dolan C.; Nilson A. (2015) Design of concrete structures. Mc-Graw Hill education, 15th Ed. New York, NY.

Appendix The following table shows all test cases considered in this study. For each one, all combinations of tf = 10, 15 and 20 mm and tw = 10, 15 and 20 mm were assessed, leading to a total of 270 models.

Tab. A1 Test Cases considered in this study

Number of L Do perforations [mm] [mm]

Number of L Do perforations [mm] [mm]

6

2 960 400 3 380 3 800 2 466 333 2 117 286

9

4 256 400 4 928 5 600 3 546 330 3 044 286

7

3 392 400 3 896 4 400 2 826 333 2 426 286

10

4 688 400 5 440 6 200 3 906 330 286 286

8

3 824 400 4 412 5 000 3 186 333 2 735 286

11

5 120 400 5 960 6 800 4 266 330 3 662 286

Steel Construction 14 (2021), No. 1

00_STCO_0121_Buch.indb 54

03.02.21 11:16

ARTICLE

Ewa Maria Kido, Zbigniew Cywiński, Hidetoshi Kawaguchi

ARTICLE

DOI: 10.1002/stco.202000025

Tradition and modernity in the structural art of steelglass structures in Japan The Committee on the Design, Construction and Production of Aesthetic Architecture, established by the Japanese Society of Steel Construction (JSSC), has for a long time stood for the promotion of appealing architecture – particularly in steel-glass structures. Such aesthetic architecture, despite being very modern, often expresses the tradition of the particular location and its culture. The choice of structural configuration is one of the tools for achieving relevant architecture. This paper, introducing attractive and innovative steel structures combined with glass, shows several examples typical of this trend in Japan.

Keywords Japanese architecture; spatial configuration; steel-glass structures; aesthetics

1 Introduction Several authors have discussed the aesthetics of Japanese architecture based on steel structures in relation to buildings and urban design [1–3], railway stations [4], air terminals [5] and passenger service centres [6]. The Japanese examples have been chosen because of their originality despite the requirements for satisfying the rigid seismic code [7] and the usual link with local traditions and aesthetics. This paper concentrates on recently completed popular steel-and-glass structures and their spatial arrangements, such as “point”, “line” and “plane”, and deals with train sheds, roofs, high-rise buildings and the façades to various stations, offices, cultural and commercial buildings – analysing their design in relation to structural aesthetics.

2

Background to structural art

Aesthetics, which gives structures form and content associated with local history and culture, is one of essentials of the “neo-infrastructure” that gets closer to people and nature [3]. The current architectural aesthetics of engineering structures usually relies not only upon the expression of its external elements (such as the façades of buildings), but goes beyond that, concentrating on the object’s structural form as a whole and its performance plus its local relations. It has already been shown by architects and engineers that the structure should result from the engineering needs and the aesthetic demands. For instance, the building is aesthetic when its efficient, innovative structure is combined within a shape that conforms to both the visual and economic factors. According to

00_STCO_0121_Buch.indb 55

Billington, the works of structural engineering design can be regarded as “structural art”, when they follow the “3E” criteria: “efficiency”, “economy” and “elegance”. “Elegance” is a term used often by structural engineers to express the aesthetics of engineering structures [8]. Structures can be beautiful on their own and when they are part of a broad architectural design.

Structural art has been created by famous designers in the past, such as Thomas Telford (1757–1834), Robert Stephenson (1803–1859), Isambard Kingdom Brunel ­ (1806–1859), Johan August Roebling (1806–1869), ­Gustave Eiffel (1832–1923), Robert Maillart (1872–1940), Eugène Freyssinet (1879–1962), Othmar Ammann (1879– 1965), Franz Dischinger (1887–1953), Fritz Leonhardt (1909–1999) and Christian Menn (1927–2018). In their lifetimes, all of them created beautiful and innovative structures, particularly bridges [9].

Further, architects have developed buildings based on innovative structures. Eero Saarinen (1910–1961) gave his structures a neo-futuristic style and symbolic associations.

His TWA Flight Center at JFK International Airport has a concrete shell structure shaped like “wings”. Frei Paul Otto (1925–2015) was an architect and structural engineer who specialized in tensile and membrane structures.

The beauty of these lightweight structures, such as the Olympic Stadium in Munich (1972), was derived from their lightness, bold elegance and unity with the natural landscape. Félix Candela Outeriño (1910–1997) was known for developing very picturesque thin shells made of reinforced concrete (e.g. Palacio de los Deportes in Mexico City). He was the teacher of the engineer-architect Santiago Calatrava, who is famous for his extraordinary buildings, beautiful bridges and expressive railway stations, artistically shaped by forces bearing the loads.

Today, structural art values are being respected by designers worldwide. In Germany the yearly reviews Ingenieurbaukunst [10] – referring to the latest achievements in engineering and architecture – show, among other things, the special concern for structural aesthetics.

3

Japanese structural art

That kind of art has developed consequently in Japan as well, taking advantage of the modernization of the country. Structural engineering has evolved since the Meiji Period (1868–1912) and was influenced by British, Ger-

© 2020 Ernst & Sohn Verlag für Architektur und technische Wissenschaften GmbH & Co. KG, Berlin. Steel Construction 14 (2021), No. 1 55

03.02.21 11:16

E. M. Kido, Z. Cywiński, H. Kawaguchi: Tradition and modernity in the structural art of steel-glass structures in Japan

structure with the traditional motif of the pagoda (Fig. 1).

Another distinctive tower in the city, the “Tokyo Tower” (1958), designed by architect Tachu Naito with Nikken Sekkei, reflects a tradition of advanced structural design.

Instead of employing welded connections, riveted joints were used to improve the building’s seismic design, despite increased structural loads.

Fig. 1

“Asahi Super Dry Hall”, 1989, and “Tokyo Skytree”, 2012

man and American technology. Architectural styles, such as Revivalism and Modernism, have been reflected not only in architecture and urban planning, but also in bridge design. The Bunriha Movement, which formed in 1920 and was the response to German Expressionism, developed aesthetics of separating the form from the structural expression. Bunriha and subsequent trends were the inspirations for Japanese aesthetics that developed throughout the 1920s and later, and included principles of Modernism, wayo kongo (a mix of Japanese and Western styles) and Metabolism. Since the 1960s, through Post-modernism, until the present, Japan has produced many significant works of structural art.

Since the 1980s, Japanese structural engineers, but also architects and industrial designers, have become very active in the discussion on aesthetics of bridges [11]. At that time, modern and post-modern architecture flourished widely in Japan – exploring unconventional shapes, new structures and materials. Today, the “Asahi Super Dry Hall” (Asahi Supa Dorai Horu) with its “Golden Flame” (1989) sculpture on the top, developed by the French designer Philippe Starck, can be considered as one of Tokyo’s symbolic structures (Fig. 1). This inverted pyramidlike building, covered with black granite and topped with a distinctive golden metal sculpture, is reflected in the elevation of the neighbouring high-rise Asahi Beer Azumabashi Building, which is clad in golden mirror glass.

Within recent years, Japanese architecture has turned broadly to structural systems of steel and glass [2]. Japanese engineers admire the light structures that can be found in traditional Japanese architecture, such as sukiya-style pavilions or chashitsu teahouses, but at the same time they must conform to the seismic requirements.

While the glass allows for a soft and smooth integration of new buildings into the mosaic of the existing urban tissue, steel provides structural systems that can be simultaneously economic, innovative and strong. Moreover, steel is the leading material for the large-span hybrid structures. Currently, new attractive buildings are employing modern construction technologies and materials – especially in membrane and frame structures, various roofs (glazed canopies, domes) and façades.

4

Systems of structural art

Structural systems with the apparent artistic values can be divided into three aesthetic categories: “points”, “lines” and “planes”. While some large structures display all these spatial attributes (e.g. roofs), some emphasize planes (e.g. façades) or points (e.g. structural joints) or lines (e.g. structural girders). In Japan, structural systems such as domes, roofs, atriums, façades and high-rise buildings which employ steel and glass are particularly visible in large sports stadiums, airport terminals, railway stations, high-rise office buildings and outstanding public buildings. Such buildings have, principally, steel-and-glass curtain walls and various steel-glass details. These materials lend these structures the ability to decrease greatly their visual weight, to provide transparency and natural light.

They inspire architectural design and together produce structural art.

4.1 Points Gradually, also other structural engineering objects, such as railway stations, along with the “station renaissance”, became a topic of aesthetic design. Traditional Japanese aesthetics, embracing diversity and contrast co-existing with each other as well as the perception of nature, have a big influence on contemporary design. The origins of aesthetic principles can be traced back to the specific “soul” of Japanese society [12], appreciation of natural phenomena and contemplation of natural surroundings.

Currently, Japan’s structural art, as in the example of bridges, has a strong background in tradition, culture and relation to the landscape [13]. The newest symbol of Japanese structural engineering, “Tokyo Skytree” (Nikken Sekkei, 2012), displays the fusion of the neo-futuristic 56

Steel-glass structures that employ outstanding spatial configurations are visible at modern railway stations [14].

Asahikawa Station (Asahikawa-eki, 2011) is an elevated large-span steel structure. It was designed by Hiroshi Naito (Naito Architect and Associates) and Japan Transportation Consultants. The train shed is supported by 20 built-up four-branch tubular columns with pin bearings resembling local trees (Fig. 2). In the structural design the condition assumed was that the bending stress undergoes no changes due to the loading at the shed column base; therefore, cast steel pin bearings were used. These “points” of the bearings are the essential elements supporting the steel-glass train shed [15].

Steel Construction 14 (2021), No. 1

00_STCO_0121_Buch.indb 56

03.02.21 11:16

Fig. 2

Asahikawa Station, Hokkaido, 2007 – four-branch columns

Fig. 3

“Terrace Canopy”, Tokyo, 2007 – steel tree-like columns

“Points” are also structurally and visually crucial in the supports for “Terrace Canopy” (Terasu kyanopı). This roof is located at Tokyo Midtown (Tokyo Middotaun, 2007), a new urban area developed by Mitsui Fudosan.

Dynamic steel columns resembling trees (Fig. 3) support the truss roof structure. It has been painted white for aesthetical reasons using a titanium oxide photocatalyst.

Such an approach expresses very well the aesthetic treatment in Japan. Structures are adapted to the specific rainy conditions. Structurally and visually crucial are the “points” at which the “tree branches” broaden out (Fig. 4).

The columns together with trees and greenery remind the observer of a real forest-like structure.

Another example of strong structural and visual “points” is “Oasis 21” (Oashisu 21, 2002) in Nagoya, designed by  nishi of the Obayashi Company.

Hideki Kasai and Koji O “Oasis 21” is a multifunctional facility containing a stage for events, shops, a green field and a bus terminal. Its outstanding feature is a large roof that consists of a spatial white truss with an oval plan form which is supported by tapered blue columns (Fig. 5). The joints are visually emphasized by the contrasting colours. The spatial configurations of steel structures usually involve more complicated spatial elements, such as “lines” and “planes”.

00_STCO_0121_Buch.indb 57

Fig. 4

“Terrace Canopy” – column details

Fig. 5

“Oasis 21”, Nagoya, 2002 – expressive joints between roof and ­columns

ARTICLE

E. M. Kido, Z. Cywiński, H. Kawaguchi: Tradition and modernity in the structural art of steel-glass structures in Japan

4.2 Lines “Lines” are usually rhythmically set structural members, e.g. girders and beams, which are the essential loadbearing elements of various structures, particularly roofs.

Both the roofs at “Tokyo Midtown” and “Oasis 21” are supported by steel beams and covered with glass. At “Tokyo Midtown” the beam “lines” are particularly light and delicate, whereas at “Oasis 21” they are more rigid and heavy. The new complex at the 5th Osaka Station, called the “Osaka Station City” (O saka Suteshon Shiti, 2011), is an example of what is in Japan an uncommon roof covering the space between the buildings and over the platforms. The “North Gate” and “South Gate” buildings of the station are connected by a bridge passage and covered by a domed roof. It was designed by the West Japan Railway Company and the JR West Japan Consultants Company. The roof, being a truss-framed structure, is supported on the north side at the 12th storey of the Steel Construction 14 (2021), No. 1 57

03.02.21 11:16

E. M. Kido, Z. Cywiński, H. Kawaguchi: Tradition and modernity in the structural art of steel-glass structures in Japan

Fig. 6

“Osaka Station City”, 2011 – station roof and plaza

Fig. 8

Kanazawa Station – “Motenashi Dome”, 2005

Fig. 7

“Osaka Station City” – roof

Fig. 9

Kanazawa Station – roof

“North Gate” and measures 180 × 100 m2 on plan (Fig. 6). It is located above the bridge passage that forms a plaza and, simultaneously, also passes over the platforms.

The basic component of the frame comprises concretefilled steel tubes and trusses which are inclined at an angle of 23° to achieve the maximum difference in level of 30 m (Fig. 7) [16]. The linear tubes – “lines” – are the most visually expressive elements. The roof finish consists of 12 rows of skylights to introduce daylight. For seismic resistance, a base with laminated rubber isolators was adopted; U-shaped dampers and oil dampers have also been installed.

4.3

Lines and planes

Very often, structures consist of at least two distinctive spatial arrangements: “lines” and “planes”. Steel-glass structures that employ various spatial configurations are particularly visible at modern railway stations [14]. Domes are strong visual elements. Kanazawa Station (Kanazawa-eki) in Kanazawa-city, Ishikawa Prefecture, was redeveloped in 2005 and adapted for the Hokuriku Shinkansen trains in 2015. Along with the redevelopment, a 58

large “Motenashi Dome” (Motenashi Domu) was constructed to cover a recreation area with water features, greenery and benches (Fig. 8). By reflecting the image of an open umbrella, it expresses the virtues of hospitability.

The dome measures 170 × 110 m2 on plan and is 29.5 m high and was designed by architect Ryuzo Saito (Shirae Building Research Institute) and structural engineer Masao Saito (Todekku Corporation). It employs spatial steel truss framing reinforced by the “lines” – beam ties.

The “planes” of the roof and the walls are fully glazed (Fig. 9).

“Lines” and “planes” are strongly associated with highrise building façades. One of the high-rise buildings at Shibuya Station, “Shibuya Hikarie” (2012), designed by Nikken Sekkei and Tokyu Architects & Engineers, is a frame structure made of concrete-filled steel tube columns and beams – including a “super-beam structure”.

“Hikarie” is a significant multifunctional high-rise station building 185.5 m high which consists of several blocks stacked up (Fig. 10). The major task in planning this structure was to include – besides the railway facilities – a 2000-seat theatre in the middle section of the building and to house several design offices in its high- and low-

Steel Construction 14 (2021), No. 1

00_STCO_0121_Buch.indb 58

03.02.21 11:16

Fig. 10 Shibuya Station, Tokyo – “Hikarie”, 2012

Fig. 11 “Abeno Harukas”, Osaka, 2014

rise sections. To accommodate the theatre within a column-free space, a structure with a minimum of four loadbearing columns was adopted. A “super-beam structure” having a truss depth equal to two storeys has been built to support the upper structure [17]. On both sides of the theatre, box-shaped concrete-filled steel tubes (CFT) are arranged as main pillars throughout the entire building.

On the elevation the horizontal “lines” divide the “planes” – the block’s curtain walls covered in glass with various degrees of permeability that take into account the function and reflect the concept of the traditional shoji screens. The structurally innovative “Hikarie” clearly expresses the concept of a multipurpose centre, which reflects well the present information technology age, thus becoming a landmark in Shibuya.

the structure in the lateral direction. The “Harukas” was upgraded, compared with other skyscrapers, by the criterion related to external forces which calls for no member to be plastically deformed by any level-2 external force.

This elegant structure has been meticulously designed considering Japan’s natural conditions and applying environmentally friendly construction methods.

The tallest building in Japan, “Abeno Harukas” (Abeno Harukasu, 2014), designed by César Pelli (Pelli Clarke Pelli Architects), is a part of the complex known as “Abenobashi Terminal Building”, which consists of Osaka Abenobashi Station, a department store and a hotel. The 300 m skyscraper has 60 storeys above ground and five below. The structure consists of a pure steel frame and a steel frame reinforced with concrete. On the elevation it has projected “planes” divided by structural “lines” (Fig. 11). The “Harukas” was constructed above the station and adjacent to the existing high-rise department store. Structurally, it has vertical voids that are connected to the horizontal outriggers, which form a “linked void structure” [18]. This allows the two tall buildings to move independently during earthquakes. The vibration dampers are located on the low-rise floors. The medium-rise floor void has outriggers on the 15th and 37th floors which suppress the deformation. The high-rise floor void serves as a passage for the air and simultaneously braces

00_STCO_0121_Buch.indb 59

ARTICLE

E. M. Kido, Z. Cywiński, H. Kawaguchi: Tradition and modernity in the structural art of steel-glass structures in Japan

One of the most beautiful structures among the cultural buildings is the library in Sendai, Miyagi Prefecture: “Sendai Mediateque” (Sendai Mediateku, 2001), designed by Toyoo Ito (Toyo Ito & Associates). Its spatial arrangement includes the “lines” of the tubes, composed of thickwall steel pipes, and the “planes”, floor slabs that are composed of a honeycomb-like network of steel sections filled with lightweight concrete, and the glass skin (Fig. 12). The first floor has been raised to include the gal-

Fig. 12 “Sendai Mediateque”, 2001

Steel Construction 14 (2021), No. 1 59

03.02.21 11:16

E. M. Kido, Z. Cywiński, H. Kawaguchi: Tradition and modernity in the structural art of steel-glass structures in Japan

4.4 Planes

Fig. 13 “Sendai Mediateque” – shaft details

Steel-glass façades are spatial arrangements that involve “planes”. High-rise structures, being the symbols of urban development projects in Japan, express particularly the aesthetic aspects of “planes”. The “Dentsu Headquarters Building” (Dentsu Honsha Biru, 2002), designed by Jean Nouvel, Jerde Partnership and Obayashi Corporation, is a 48-storey building (213 m) with a total floor area of 231 701 m2. Its outstanding features are the boomerangshaped office floors and the gently curving façade made of ceramic printed glass and covered with vertical and horizontal gradations (Fig. 15). The requirements were: a long service life, symbiosis with the environment and energy-savings. The shape of the boomerang – 120 m longside span and 41 m short-side span – required the shortspan bending deformations to be controlled. The structural features of the building include the adoption of a concrete-filled steel tube (CFT) structure like that of ­“Hikarie”, use of fire-resistant steel, securing the shortside span horizontal rigidity through the use of a “super mega-frame” system, adoption of seismic dampers and safeguarding stability by using vibration-control devices installed at the top of the building. The “Dentsu”, with its glass curtain walls and boomerang shape, reflects the sublime Japanese aesthetics. Despite being a large building, it looks lightweight and has become an attractive part of Tokyo’s cityscape.

Another distinctive skyscraper, the “JP Tower” (JP Tawa, 2012), has replaced the former building housing Japan Post. A large portion of the original five-storey low-rise frontage of Tokyo Central Post Office was preserved and redeveloped by Kengo Kuma (Kengo Kuma and Associates). The fact of preservation – by being replaced by a

Fig. 14 “International Library of Children’s Literature”, Tokyo, 2015

lery. This unique structure is composed of six floor slabs supported by 13 shafts made of latticed steel tube columns that rise from the ground to the roof. These shafts, varying in size, also contain building services, technological systems and escalators and stairs (Fig. 13). The vertical loadbearing elements are also reminiscent of the trees lining the boulevard in front of the building.

The combination of “lines” and “planes” is also displayed at the “International Library of Children’s Literature” (ILCL, Kokusai Kodomo Toshokan). The ILCL consists of the historical “Brick Building” built in 1906 and new the “Arch Building” designed by Tadao Ando (Tadao Ando Architect & Associates) and Nikken Sekkei, which was completed in 2015. The preservation project included the improvement of its structural stability and modernization works and has provided more space [19]. A new glass-box entrance to the original masonry building has a smooth glass “plane” and the vertical “lines” of the steel structure (Fig. 14). The simple design embraces the importance of a minimal intervention in order to preserve the historical building.

60

Fig. 15 “Dentsu Headquarters Building”, Tokyo, 2002

Steel Construction 14 (2021), No. 1

00_STCO_0121_Buch.indb 60

03.02.21 11:16

ARTICLE

E. M. Kido, Z. Cywiński, H. Kawaguchi: Tradition and modernity in the structural art of steel-glass structures in Japan

Fig. 17 “Mikimoto Ginza 2”, Tokyo, 2005 Fig. 16 “JP Tower”, Tokyo, 2012

corresponding structure – is connected to Japanese culture and the tradition of shikinen sengu – the ritual of the total rebuilding of Shinto shrines which occurs every 20 years. It serves also as a tool for transferring the knowledge about traditional building techniques from one generation to another. The steel-and-glass tower portion designed by Helmuth Jahn (JAHN) and Werner Sobek (Werner Sobek Group) has 40 storeys above ground and is 195.7 m high (Fig. 16). It integrates the outline of the existing building within its façade. Its sustainable design includes photovoltaic panels with 10 % light transmittance, which were adopted for the curtain walls.

It allows solar gains to be controlled while the absorbed radiation is converted into electricity. The high-performance building envelope integrates a triple-glazed ventilated cavity wall that reduces heat gains in warm seasons and heat losses in cooler seasons. Automated sunshades are located within the cavity to reflect solar radiation and to release the heat back into the cavity from where it can be vented out or retained to reduce heat losses during winter.

Commercial buildings located in a densely built-up urban centre often express their concept by relying on innovative structures for their façades. “Mikimoto Ginza 2” (Mikimoto Ginza 2, 2005) employs a composite structure – a “steel plate concrete structure” (CFSP) for the outer walls – forming a “tube structure”. Here, the vertical and horizontal loads are all borne by four outer peripheral surfaces [20]. The building, designed by Toyoo Ito (Toyo Ito & Associates, Architects) and Taisei Corporation, has nine storeys and a total floor area of 2295 m2. The CFSP is a structure in which concrete is filled and integrated between two steel plates connected by studs. The concrete filling contributes to the building’s rigidity and the

00_STCO_0121_Buch.indb 61

buckling resistance of the steel plates. This is a very thin wall-type structure in which the concrete layer of 200 mm is poured between 6–12 mm thick steel plates. There are no columns in the interior space, which allows a great amount of flexibility for the interior design. The steel plate carries the stresses of all the members. The welded part of the outer wall unit has been carefully polished and smoothed. The wall has been covered with a multi-layer pearl coating inspired by Mikimoto pearls. Such an innovative design allowed the realization of the architectural concept – the oval “holes” on the building elevation (Fig. 17). These openings appear to be arranged at random. However, since some of them are placed at the corners (where there would typically be a column), it proves that there is an underlying sophisticated construction system strong enough to compose such a façade. The design is based on a concept of expressing the brand through the structural design similar to the one applied at “Tod’s Omotesando” (2004), created by the same architect.

The main Mikimoto store – “Mikimoto Ginza Headquarters” (Mikimoto Ginza honten) – is a 12-storey building with an elevation made up of glass pieces designed by Hiroshi Naito and Kajima Design. It was completely rebuilt at Ginza, on the site of the historical building (1899), and opened in 2017. The flagship store’s façade made up of 38 000 glass pieces symbolizes the image of the “brightness of the spring sea” and is associated with the nature of the Mikimoto brand (Fig. 18) [21]. According to architect Naito, the importance of the design of this glass façade is that it puts a focus on the quality of how light is seen from the interior space rather than on the exterior design itself. To avoid the risk of breakage, 10 mm laminated glass was used instead of tempered glass. Generally, tempered glass is thought to be strong glass, but sometimes NiS (nickel sulphide) impurities may be present.

Steel Construction 14 (2021), No. 1 61

03.02.21 11:16

E. M. Kido, Z. Cywiński, H. Kawaguchi: Tradition and modernity in the structural art of steel-glass structures in Japan

Fig. 18 “Mikimoto Ginza Headquarters”, Tokyo, 2017

Compressive and tensile stress layers are generated inside the tempered glass, which attains its strength by balancing them. However, the impurities in the tensile stress layer increase and cause minute scratches, which may cause damage. On the other hand, float glass that has not been heat-treated does not suffer the risk of spontaneous failure, because no stress layer is created inside the glass.

The use of laminated glass was a measure to prevent it from falling if it breaks. The structure displays great quality of construction. The supporting material has small details welded to the wall-frame structure (FB) one by one, with a scoop-shaped receiving material (hot-dip galvanizing phosphoric acid treatment) to strengthen the presence of the glass itself (Fig. 19). The glass inside the 1.95 × 2.25 m unit frame was installed at the factory, and only the joints were worked on site. The installation of the glass pieces was completed in three months. This design originated from the unique sensibilities of Japanese architecture, displaying, through the openings, the outside world inside (e.g. the shadow of a leaf on a shoji screen in a tea-room chashitsu).

Steel-and-glass façades are important structural means of architectural expression. Some of these “planes” may have dynamic oval shapes. The building for the “National Art Center” (Kokuritsu Shin-Bijutsukan, 2007), designed

by Kisho Kurokawa, is an excellent example of such an expressive elevation (Fig. 20). The museum with a total floor area of 49 834 m2 consists of a vast exhibition space (130 × 60 m) – the largest in Japan – and an irregularly shaped 3000 m2 atrium. The 23 m high atrium has a steelglass façade with a three-dimensional curved surface. The roof of the atrium portion is supported by 15 slender flatsteel columns placed at intervals of about 2 m. The base isolation structure allowed for a column-free space in the atrium area. The upper structure of the building is a partly braced rigid steel frame. For the structural mullions, flat 62

Fig. 19 “Mikimoto Ginza Headquarters” – façade details

Fig. 20 “National Art Center”, Tokyo, 2007

steel elements were bent in the axial direction and made into a 3D truss. The frame structure is stiffened against buckling by horizontal truss beams every 3 m. The structure has been designed for the possibility of earthquakes, with the allowable stress designed for a horizontal quake.

The transparent atrium expresses the concept of the ambiguity of the traditional Japanese space, where the entrance portion is a part of the interior as much as the exterior.

5 Conclusion In Japan there are many other outstanding buildings that express the beauty of structural design, like some finished recently in 2019 (“Shibuya Scramble Square” at Shibuya Station and “Okura Hotel” in Tokyo), as well as numerous new ones that are currently under construction (“Toranomon Hills Station Tower” in Tokyo). The exam-

Steel Construction 14 (2021), No. 1

00_STCO_0121_Buch.indb 62

03.02.21 11:17

ples given here show that, nowadays, modern structural design is an essential tool in providing an aesthetic architecture. “Points”, “lines” and “planes”, as the basic configurations based on steel and glass, embody considerable potential for achieving innovative designs. Various façades using glass and steel also express traditional Japanese sensibilities. On historical buildings it is important to display the historical structures and details and at the same time ensure safety and durability. The transparency of glass allows a proper expression of the historical architecture and its beauty, generating thoughts of refinement and reflections. Both steel and glass evoke impressions of lightness, which decrease the perception of the intervention into the historical building fabric and underline the up-to-date shapes of the new high-rise buildings. Japanese

examples show that the awareness of tradition, building culture and aesthetics is very intense and well reflected in modern architecture, and that the overall outcomes are rewarding.

ARTICLE

E. M. Kido, Z. Cywiński, H. Kawaguchi: Tradition and modernity in the structural art of steel-glass structures in Japan

Acknowledgements The authors wish to thank Prof. Dr. Eng. Hideo Nakamura, professor emeritus at the University of Tokyo, visiting professor at the University of Stuttgart and president emeritus at Tokyo City University, for his support and guidance regarding the role of structural engineering infrastructure in Japan.

References [1] Kido, E. M.; Cywiński, Z. (2013) The new steel-glass architecture of buildings in Japan in: Steel Construction – Design and Research 6, No. 3, pp. 229–237.

[2] Kido, E. M.; Cywiński, Z. (2017) Aesthetic perception of steel-glass architecture in Japan in: Stahlbau 86, No. 6, pp. 515–526.

[3] Kawaguchi, H. (2019) Space design that grows with cities in: Urban Innovation, Asakura Publishing Co., Ltd., pp. 101–112.

[4] Kido, E. M.; Cywiński, Z. (2014) The new steel-glass architecture of railway stations in Japan in: Steel Construction – Design and Research 7, No. 3, p. 208–214.

[5] Kido, E. M.; Cywiński, Z. (2014) The new steel-glass architecture of air terminals in Japan in: Steel Construction – Design and Research 7, No. 4, pp. 246–251.

[6] Kido, E. M.; Cywiński, Z. (2015) The new steel-glass architecture of passenger service centres in Japan in: Steel Construction – Design and Research 8, No. 3, pp. 210–215.

[7] Ishiyama, Y. (2020) Earthquake Damage and Seismic Code for Buildings in Japan. http://ares.tu.chiba-u.jp/peru/pdf/ meeting/120817/M6_Ishiyama.pdf [accessed on 17 Feb 2020] [8] Billington, D. P. (1983) The tower and the bridge. Princeton: Princeton University Press.

[9] Kleinmanns, J.; Weber, C. (2009) Fritz Leonhardt 19091999. Die Kunst des Konstruierens. Stuttgart: Axel Menges.

[10] Bundesingenieurkammer (2019) Ingenieurbaukunst. Berlin: Ernst & Sohn.

Authors Dr. Eng. Arch. Ewa Maria Kido (corresponding author) kido@ctie.co.jp CTI Engineering Co. Ltd. Research Center for Sustainable Communities 2-14-5 Nihonbashi Kakigaracho, Chuo-ku, Tokyo 103-0014, Japan Tokyo City University, Dept. of Urban Engineering

Prof. dr hab. inż. Zbigniew Cywiński zcywin@wp.pl Faculty of Civil & Environmental Engineering Gdansk University of Technology ul. G. Narutowicza 11/12 80-233 Gdańsk, Poland

00_STCO_0121_Buch.indb 63

[11] Kido, E. (1997) Aesthetics and philosophy in bridge design in Japan in: Journal of Architectural Engineering 3, No. 1, pp. 42–53.

[12] Mizuno, K.; Mizuno, H.; Yamakuse, Y. (2015) Soul of Japan. Tokyo: IBC Publishing Inc. [13] Kido, E. M.; Cywiński, Z. (2019) The colours of steel bridges in Japan – principles and examples in: Stahlbau 85, No. 3, pp. 181–194.

[14] Kido, E. M.; Cywiński, Z. (2018) The steel-glass art of railway stations in Japan in: Stahlbau 87, No. 6, pp. 611–621.

[15] Kawaguchi, M.; Aso, Y. (2011) Asahikawa Railway Station – structural design of open large-span station building in: Steel Construction Today & Tomorrow 34, pp. 12–14.

[16] Umeki, T. (2011) Osaka Station in: Steel Construction Today & Tomorrow 34, pp. 8–11.

[17] Akahoshi, T. [ed.] (2014) Design and construction of Shibuya Hikarie in: Steel Construction Today & Tomorrow 41, p. 3.

[18] Ando, K. [ed.] (2015) Big – compact. Abeno Harukas super tall city. Steel Construction Today & Tomorrow 44, pp. 1–2.

[19] Ishida, J. (2018) Tadao Ando and Tokyo in: Casa-Brutus 224, No. 11, pp. 32–33.

[20] Taisei Design (2019) Mikimoto Ginza 2. http://www.taiseidesign.jp/de/works/2005/mikimoto.html [accessed on 16 Oct 2019].

[21] Kamioka, S.; Harashima, H. (Kajima Design); Naito H. (2012) Mikimoto Ginza Honten in: Shinkenchiku 12, pp. 76–80.

Prof. M. Arch. Hidetoshi Kawaguchi kawahide@tcu.ac.jp Tokyo City University, Faculty of Urban Life Studies 8-9-18 Todoroki, Setagaya-ku Tokyo 158-8586, Japan How to Cite this Paper Kido, E. M.; Cywiński, Z.; Kawaguchi, H. (2021) Tradition and modernity in the structural art of steel-glass structures in Japan. Steel Construction 14, No. 1, pp. 55–64. https://doi.org/10.1002/stco.202000025 This paper has been peer reviewed. Submitted: 6. April 2020; accepted: 17. August 2020.

Steel Construction 14 (2021), No. 1 63

03.02.21 11:17

Bill Addis (Ed.)

Physical Models Their historical and current use in civil and building engineering design the book summarizes the history of model testing by design and construction engineers in a single volume for the first time

S E R I E S

The book traces the use of physical models by engineering designers from the eighteenth century, through their heyday in the 1950s-70s, to their current use alongside computer models. It argues that their use has been at least as important in the development of engineering as scientific theory has.

PhysicAl ModEls

H I S T O R Y

model testing is alongside knowledge of materials and structural behaviour a major driver in progress in civil and building engineering

Bill Addis (Ed.)

C O N S T R U C T I O N

-

Their historical and current use in civil and building engineering design

2020 · 1114 pages · 896 figures · 14 tables Hardcover ISBN 978-3-433-03257-2

€ 139*

eBundle (Print + PDF) ISBN 978-3-433-03305-0

€ 229*

ORDER +49 (0)30 470 31-236 marketing@ernst-und-sohn.de www.ernst-und-sohn.de/en/3257

* All book prices inclusive VAT.

1246.indd 11 00_STCO_0121_Buch.indb 64

21.09.2020 14:21:57 03.02.21 11:17

Steel Construction News 1/2021 ECCS NEWS

ECCS member news ECCS welcomes a new member: PIKS – Polish Chamber of Steelwork

European Steel Design Awards 2021: Call for entries is open!

The Polish Chamber of Steelworks is a self-regulatory organization established in June 1996 by 115 founding members associating, in different periods, 125–150 companies of various size, ownership status and activity profile, including: – Steel structure manufacturers and assembly companies, – Companies cooperating in production and distribution of steel, aluminium systems and lightweight casing, technology and fasteners and welding materials as well as deliveries and services with respect to corrosion pro­ tection and fire safety, – Scientific, research, design and specialist entities.

For more information see www.piks.com.pl/en

List of National Constructional Steel Days in 2021 Czech Republic: Czech Steel Conference 4 November 2021, www.caok.cz Denmark: Danish National Steel Day 11 November 2021, www.steelday.dk Norway: Norwegian Steel Day 11 ­November 2021, www.norskstaldag.no

The submission of national projects for the 2021 European Steel Design Awards 2021 has been launched. The ESDA Ceremony which will be held in Paris in September. This years call addresses as usually all kinds of steel structures but ­fosters also a special award for bridges.

To participate, see your national steel construction association or send your request to eccs@steelconstruct.com.

Switzerland: Swiss National Steelday+ 7 October 2021, Bern, www.steelday.ch Turkey: Turkish Constructional Steel Day 24 November 2021 Eurosteel – 9th European Conference on Steel and Composite Structures Sheffield 1–3 September 2021, eurosteel2020.com

Projects must be submitted by 30th April 2021.

ECCS NEWS

ECCS R&D activities

RFCS projects FAILNOMORE – mitigation of the risk if progressive collapse in steel and composite frames under exceptional events

The main aim of this project is to produce a set of practical and user-friendly design guidelines for mitigating the risk

00_STCO_0121_Buch.indb 65

of progressive collapse of steel and composite structures subjected to exceptional events such as impact and explosions.

This will be based on recent research projects and available normative documents in order to propose a common design methodology to be implemented in the European practice. The main dissemination will be through a design manual including worked examples, which will be drafted in various national languages, as well as a series of training workshops in 11 European countries.

The project started on 1 July 2020 and is coordinated by University of Liège.

More information at www.steelconstruct. com/EUProjects/Failnomore

FREEDAM + Valorisation of knowledge for FREE from DAMage steel connections The project FREEDAM (RFSR-CT-​201500022), regarded the design and testing of innovative connections equipped with friction dampers able to withstand without any damage the seismic events.

FREEDAM+ aims at the valorization, the dissemination and the extension of the results to a wide audience.

Steel Construction 14 (2021), No. 1 65

03.02.21 11:17

Steel Construction News The dissemination will turn around preparation of a series of informative documents concerning the connections equipped with friction dampers in 13 languages (English, Spanish, French, German, Italian, Dutch, Portuguese, Czech, Bulgarian, Romanian, Greek, Turkish and Slovenian).

The project started on 1st July 2020 and is coordinated by the University of Salerno.

More information at www.steelconstruct. com/EUProjects/Freedam

HORIZON 2020 projects PULVERCOAT

PulverCoat is a new generation of advanced thermosetting powder coatings that polymerize at lower temperatures (110–130°C) with a reaction mechanism 10 times faster than common powder coatings, enabling curing to take place in just 3–5 minutes.

Due to COVID-19, the project ending on 30 September was extended for a period of 6 months.

More information at www.pulvercoat.eu

enterprise-like, which will provide the European Innovation Ecosystem (the sector, the industries and companies) with the necessary technologies, resources and services to uptake a set of game changing, efficient and cost- effective innovative processes to manufacture nano-enabled industrial and consumer products as well as the necessary testing capabilities to demonstrate nano-enhanced goods features. The project is coordinated by ECCS. The NewSkin innovative manufacturing up-scaling and testing facilities will provide the sector with the necessary tools to create and validate system prototype demonstration in operational environment, new technologies to meet the challenges of key European Industries such as Steel, Ceramics, Transport, Water Treatment and the General industry.

NEW SKIN – Innovation Eco-system to Accelerate the Industrial Uptake of Advanced Surface Nano-Technologies

NewSkin will impact the Steel Construction Industry in four different areas:

The NewSkin project aims to create an “Open Innovation Test Bed (OITB)”, this is a new concept launched by the Commission in order to further support the SMEs sector. An OITB is a legal entity,

– Newskin will transfer the Steel Industry novel nano-technologies that will allow to reach and demonstrate new levels of performance and durability (ice, fouling, corrosion, wear and fire resistance) under combined stresses in harsh environments and extreme industrial conditions.

– Advanced continuous processes will be also transferred to the Steel Industry for the production of functional surfaces on steel cladding, envelopes, structures and components.

66

– NewSkin will transfer the Innovation Ecosystem high performance nano-coatings and structures for steel drilling, machining and cutting machine tooling and components increasing processes efficiency, reducing costs and environmental impacts as well as avoiding the lines shutdowns and major equipment failures.

– Highly efficient water treatment technologies to recycle and reuse of cutting fluids and other steelwork related effluents.

ECCS is leading the NewSkin Consortium in the identification of challenges and opportunities within the Steel Industry through the ECCS Technical Committees and the ECCS network. In parallel, ECCS has launched the high-performance coatings and technologies engagement activities to promote the uptake of novel technologies by the Steel Construction Industry achieving new levels of performance in steel protection and the deployment of novel functionalities.

The NewSkin project has been presented to the ECCS Technical Management board on 18 November 2020 and to ECCS National association members on 19 November 2020. It has also been presented to the TCs dealing with fire protection, surface protection, stability, composite structures, sustainability and energy supporting structures.

More information at www.steelconstruct.com/EUProjects/

Steel Construction 14 (2021), No. 1

00_STCO_0121_Buch.indb 66

03.02.21 11:17

Steel Construction News ECCS NEWS

News from Europe Construction in national recovery plans: The built environment must be a priority for next generation

may be prioritized in the national Recovery Plans as it can play a key role in the recovery and resilience of the EU’s economy.

However, this must be requested by Member States that have full ownership of their national Recovery Plans and should be the result of a consultation exercise with national stakeholders.

On 3rd December, the Construction 2050 Alliance brought together experts from all over Europe, including representatives from the European Commission, the European Parliament, and national governments. They discussed the important role that construction may play as the severely hit European economy recovers from the COVID-19 pandemic. The Alliance’s key message is that the built environment must be a key priority in all national Recovery plans and in the new EU funding initiatives.

As in our fight against climate change, for which the construction ecosystem plays a key role, the built environment provides solutions to mitigate the impact of the pandemic. Indeed, while it was estimated that on average European citizens spend more than 90% of their time indoors, this has significantly increased as confinements and curfews have become the new norm. Living in safe, healthy, properly ventilated and energy efficient buildings is thus crucial for EU citizens, the economy, and the planet.

It is for the reasons highlighted here above that, the members of the Construction 2050 Alliance held a high-level discussion on the role that the built environment should play in the post-COVID-19 recovery, more specifically, its weight in future decisions on European funding in response to the pandemic. This first public event of the Construction 2050 Alliance allowed for open and transparent exchanges between Member States representatives, Members of the European Parliament (MEPs), high-level Commission officials, as well as European construction experts. Whilst Member States presented their plans for the built environment in their respective national strategies under the new recovery instrument, “Next Generation EU”, the European Commission confirmed that construction

00_STCO_0121_Buch.indb 67

On the same line, MEPs Iskra Mihaylova (Bulgaria, RE) and Pernille Weiss (Denmark, EPP) suggested that national debates feed each other through an exchange of best practices on effective policy measures. The representatives of the Alliance stressed that investments in the renovation and modernization of the European buildings and infrastructure will deliver positive results in terms of health, comfort, adaptability and environmental impacts. Such investments offer key opportunities for a built environment that would be more resilient, safer, more comfortable, more cost-efficient and sustainable.

Therefore, the 47 EU associations that form the Alliance call together for the built environment to be a key priority in all national recovery plans and in the new EU funding initiatives.

New Circular Economy Action Plan

1. What is the expected impact of ­COVID-19 on the new CEAP? It will be an imperative step in Europe’s journey to become climate neutral by around mid-century. To enable this change, we urgently need a functioning market for quality secondary raw materials and circular products.

The Commission’s action plan has a real potential to help achieve these markets. It can lead to more circular product designs, better consumer awareness of wasteful behaviour, higher demand for circular and low carbon products, as well as new technologies and improved waste management systems. It can also focus on better implementation in the member states and create similar policy frame-

works/standards across the G20. European businesses are fully engaged as is shown by the 200 circular business examples on www.circulary.eu For example, companies are working on new business models that aim to create value for consumers by extending the lifetime of products. COVID-​ 19 is providing an unprecedented shock to the global system that will result in several negative GDP quarters, with the EU expected to experience a GDP contraction of 7.4–7.9% in 2020 (Commission 2020 Spring Economic Forecast / BusinessEurope 2020 Spring Economic Outlook), while more severe scenarios putting this figure at around –12% in 2020 (ECB).

Though the EU’s policy response has also been unprecedented, the recovery will likely only be gradual. Overall, Europe could face an €850bn shortfall in private sector investment in the next couple of years (2020 SEF), of which an estimated €25bn loss is in total R&D investment. This will undoubtedly have an impact on the financial capacity of countries and companies to invest in a circular and sustainable economy.

2. What view on lifecycle of products?

Should it just look at the recyclability of products, or also other elements (e.g. longevity)?

The lifecycle of a product should be based on more than simply its recyclability, as recycling alone will not be enough to create a fully functioning circular economy in Europe. All significant stages of the product’s lifecycle need to be considered. This can include longevity as a means to promote waste prevention, which features at the top of the waste hierarchy. In many cases, a proper selection of materials and protecting them with additives (such as in the case of plastics) provide a sensible “no-regret” contribution to circularity. That said, it would be important to define longevity carefully.

Source: BusinessEurope, position paper, new circular economy action plan: https://www.businesseurope.eu/

Steel Construction 14 (2021), No. 1 67

03.02.21 11:17

Steel Construction News ECCS NEWS

News from the world GLOBE – Global Consensus on Sustainability in the Built Environment

“Nothing less than a transformative and united worldwide effort from all stakeholders of the construction sector is required for human society to be successful in sustainable development, and in the mitigation of the disastrous consequences of climate change at global and local scales”. This is the central message of the GLOBE Consensus, which has been recently stipulated by an international group of experts, mandated by seven of the leading professional associations in the domain of construction engineering1.

GLOBE stands for Global Consensus on Sustainability in the Built Environment and it highlights the global challenges associated with the built environment as a main contributor to climate change.

The GLOBE Consensus is targeted to societal decision makers and professionals in the construction industry and calls for a coordinated and joint effort to counter global climate change. The objective is to make players in the construction area

aware of their enormous responsibility; GLOBE puts sustainability in the construction sector and the built environment on the global agenda – at the same level of importance as safety and durability. The consensus document further addresses facilitators and suggests clear actions, which must be implemented immediately.

“Sustainability and mitigation of climate change is a global challenge – that must be addressed in a global collaborative and focused effort – and this is what the GLOBE Consensus is really all about”, according to Prof. Michael Havbro Faber, President of the Joint Committee on Structural Safety, Aalborg University, Denmark.

“With increasing urbanization and construction demand and more and more limited resources, the construction industry and the profession of civil engineers become the most relevant drivers for positive socio-economical and environmental developments and more sustainable processes. Nevertheless, most actors are not even aware of their individual role and responsibility in this challenge.

Therefore, the GLOBE consensus is a milestone, which directly addresses all actors in the entire built environment and encourages them to become change drivers towards a better future perspective”, Dr. Wolfram Schmidt (BAM) states,

who studies local material solutions for global challenges.

“Global warming is the major challenge facing humanity. Everything must be done to lower emissions, and the built environments represents a major part of embodied CO2”, Prof. Karen Scrivener (EPFL) states, who is a leading expert in sustainable cement and production technology.

Judith Hardy, who is Secretary General of RILEM and wholeheartedly dedicated a lot of effort into the successful finalization of GLOBE states “I am pleased to support the GLOBE action and to provide through RILEM the service to spread the word amongst scientists and practitioners” The expert group strongly proposes that a globally composed task force is established and mandated to support supranational and national policy makers with respect to sustainable development in the construction sector and the built environment.

More detailed information on the GLOBE Consensus may be found on the GLOBE homepage where the GLOBE Consensus may be found in English, Chinese, Spanish, German and Kiswahili and more language translations are in process: www.rilem.net

ECCS NEWS

Publications 139 – From Assessment to Best Practice – A collection of historical fatigue damage cases in steel and composite bridges, TC6 Fatigue and Fracture.

140 – Background information on fatigue design rules – statistical evaluation, TC6 Fatigue and Fracture.

68

142 – European Recommendations for the Design, Detailing and Application of Fastenings for Sandwich Panels, TC7 TWg 7.9 Sandwich Panels and related Structures, together with CIB.

401 – Diseño de Estructuras de Acero (Spanish version of the Design Manual for Steel Structures).

Building logbook state of play

Steel Construction 14 (2021), No. 1

00_STCO_0121_Buch.indb 68

03.02.21 11:17

Steel Construction News Report 2 of the study on the development of a European Union framework for buildings’ digital logbook Over the lifespan of buildings, data is routinely collected by multiple stakeholders for various reasons as many decisions rely on data availability. However, the lack of a common approach and structure among stakeholders which would make this wealth of information widely available, organised and easily accessible, makes this data often unusable as it gets discarded, forgotten or it is not compatible with other stakeholders’ systems. The lack of an overarching structure shared across the built environment leads to information asymmetry, lack of transparency and higher risk for investment and de-

cisions. Tools for information management applied to buildings have the potential to enable better decision making throughout the building lifespan: management of technical and function aspects, safety, conservation of economic value, certification, improved energy and environmental performances, etc. Organised and shared data that can be re-used would not only reduce uncertainty but also time and cost needed for recollecting missing information. In a more simplistic concept, building logbooks are a repository developed for the management of buildings information. Overtime, due to the complexity of buildings and the number of stakeholders involved, the idea of building logbooks has developed in different ways, resulting in the creation of an

array of tools and requirements across Europe and worldwide for collecting and using buildings’ data. To be able to inform future decisions and set a direction that will support the widespread use of digital building logbooks across Europe, it is important to understand what is already available, in particular what works and what doesn’t, in the existing (and past) building logbooks.

Building logbook state of play – Publications Office of the EU (europa.eu): https://op.europa.eu/en/publication-­ detail/-/publication/58580f81-06b7-11​ eb‑a511-01aa75ed71a1

NEWS

International Colloquium on Stability and Ductility of Steel Structures 2022 in Aveiro, Portugal The International Colloquium on Stability and Ductility of Steel Structures – SDSS 2022 will be held at University of Aveiro, Portugal, on 14-16 September 2022. It follows the successful series of SDSS colloquia, which started in 1972, in Paris, and had the last five editions held in Budapest, Hungary (2002), Lisbon, Portugal (2006), Rio de Janeiro, Brazil (2010), Timisoara, Romania (2016) and Prague, Czech Republic (2019).

The series of International Colloquia on Stability and Ductility of Steel Structures aims at providing a forum for discussion and dissemination, by researchers and designers, of the most recent advances in theoretical, numerical and experimental research in the field of stability and ductility of steel and composite steel and concrete structures. Special emphasis is

always given to new concepts and procedures concerning the analysis and design of steel structures and to the background, development and application of rules and recommendations either appearing in recently published codes and specifications or about to be included in their upcoming versions. The SDSS 2022 participants will be able to become familiar with the most recent achievements in the advancement of knowledge and application in the above fields, share the latest trends and developments and exchange ideas on current and future research needs.

ECCS will organize parallel special sessions. Publisher Ernst & Sohn and its Steel Construction journal are media partner of SDSS 2022. Steel Construction journal calls again for a best paper award and will publish selected papers afterwards.

International Colloquium on Stability and Ductility of Steel Structures 2022 14 – 16 September 2022 University of Aveiro, Portugal www.ua.pt/pt/sdss2022

The SDSS series has been supported by the Structural Stability Research Council (SSRC) and by the European Convention for Constructional Steelwork (ECCS). As in previous colloquia, the Structural Stability Technical Committee (TC8) from

NEWS

STCO Online Live Seminar #2 with Prof. Knobloch, Prof. Kuhlmann and Prof. Taras: Structural member stability in the second generation of Eurocode 3 The second Steel Construction Online Live Seminar Structural member stability in the second generation of Eurocode 3 with Prof. Markus Knobloch (Ruhr-Univ.

Bochum), Prof. Ulrike Kuhlmann (Stuttgart Univ.) and Prof. Andreas Taras (ETH Zurich) as well as Anna-Lena Bours and Fabian Jörg takes place online on 26 March 2021, 10.00 to 12.00 a.m. CET. The OLS gives an overview of the devel-

00_STCO_0121_Buch.indb 69

opments of the structural member verification in prEN 1993-1-1:2020 “Eurocode 3: Design of steel structures – part 1-1: General rules and rules for buildings”, of the second generation of Eurocodes.

Many improvements to design rules have been established with respect to structural analysis, resistance of cross-sections and stability of members. The OLS focuses on member stability design rules and

deals with the basis for the calibration of partial factors, the introduction of more economic design rules for semi-compact sections, methods for structural analysis in relation to the appropriate member stability design rules, new design rules for lateral torsional buckling plus other developments and innovations. The upcoming most relevant changes to member buckling design rules are thus illustrated.

Steel Construction 14 (2021), No. 1 69

03.02.21 11:17

Steel Construction News – Annex E: Basis of the calibration of partial factors

Results of resistance calculations for ­different rolled sections in grade S460

The Keynote on structural member stability in Eurocode 3 addresses the following topics in detail: 1. General background to the development of – the second generation of Structural Eurocodes – prEN 1993-1-1:2020 2. Enhancing “ease of use” for structural analysis (methods of analysis for ultimate limit state design checks) 3. Improvements to – classification of cross-sections – design rules for semi-compact sections – imperfections – design rules for lateral torsional buckling

Extension and innovation of the scope of stability verifications circular and elliptical hollow sections buckling curves for heavy sections, for angles and for hot rolled I- and Hsections in grade S460 – local load introduction without ­stiffeners 4.

– – –

The keynote is based on a two part paper

by Knobloch, M.; Bureau, A.; Kuhlmann, U.; da Silva, L. S.; Snijder, H. H.; Taras, A.; Bours, A.-L.; Jörg, F. Structural member stability verification in the new Part 1-1 of the second generation of Eurocode 3, Part 1: Evolution of Eurocodes, background to partial factors, cross-section classification and structural analysis (DOI: 10.1002/stco.202000016), Part 2: Member buckling design rules and further innovations (DOI: 10.1002/ stco.202000027), which have been published in Steel Construction 13 (2020), ­issues 2 and 3.

STCO OLS #2 Structural member stability in the second generation of Eurocode 3 Prof. Markus Knobloch, Prof. Ulrike ­Kuhlmann, Prof. Andreas Taras et al.

26 March 2021 10.00 – 12.00 a.m. CET Info und registration: www.ernst-und-sohn.de/stco-seminar

NEWS

New European Bauhaus: European Commission launches design phase

The European Commission has launched the design phase of the New European Bauhaus initiative, which is an environmental, economic and cultural project, aiming to combine design, sustainability,

70

accessibility, affordability and investment in order to help deliver the European Green Deal. The core values of the New European Bauhaus are thus sustainability, aesthetics and inclusiveness. The goal of the design phase is to use a co-creation process to shape the concept by exploring ideas, identifying the most urgent needs and challenges, and to connect interested parties. As one element of the design phase, this spring, the Commission

will launch, the first edition of the New European Bauhaus prize.

This design phase will lead to the opening of calls for proposals in autumn this year to bring to life New European Bauhaus ideas in at least five places in EU Member States, through the use of EU funds at national and regional level. ­Further information can be found at https://europa.eu/new-european-bauhaus

Steel Construction 14 (2021), No. 1

00_STCO_0121_Buch.indb 70

03.02.21 11:17

Events REVIEWERS

List of reviewers who have completed at least one review for Steel Construction in 2020. The editors would like to thank all reviewers, also on behalf of the authors.

Mohammad Al-Emrani Vincente Alero Hamidreza Babaali Eduardo de Miranda Batista Daniel Bitar Tiago Braga Abecasis Alain Bureau Martin Classen Luís Simões da Silva Buick Davison Jean-Francois Demonceau Pampa Dey Florea Dinu Imke Engelhardt Markus Feldmann Cai Gaocuang Leroy Gardner

Max Gündel Jerome Hajjar Gregory James Hancock Stephen James Hicks Jörg Hildebrand Jakob Laigaard Jensen Markus Knobloch Raffaele Landolfo Luiz Alberto Araújo de Seixas Leal Martin Leitner Gerhard Lener Guo-Qiang Li Richard Liew Luciano Lima Frithjof Marten Pierre-Olivier Martin Federico Mazzolani Enrique Mirambell Christoph Odenbreit Kiyoshi Ono Matthias Oppe Kim Rasmussen

Carlos Rebelo Paul Richards Manuel L. Romero Pavel Ryjáček Amir Saedi Daryan Daniel Schäfer Gang Shi Geralt Siebert Hubertus Snijder Léopold Sokol Hans-Albert Städler Andreas Taras Detlef Ulbrich Viorel Ungureanu Brian Uy Ioannis Vayas Michael Vormwald František Wald Nesrin Yardimci Kan Zhou

Events Place and date

Event

Details

Online 26 March 2021

Steel Construction – Online Live Seminar Prof. Knobloch, Prof. Kuhlmann and Prof. Taras: Structural member stability in the second generation of Eurocode 3

www.ernst-und-sohn.de/en/steelconstruction-online-live-seminar

Guimarães, Portugal 12–14 May 2021

18th International Probabilistic Workshop (IPW2020)

ipw2020.com

Poznań, Poland 16–18 June 2021

14th International Conference on Metal Structures

icms2021.put.poznan.pl

Stromberg, Germany 26–30 July 2021

9th International Conference on Composite Construction in Steel and Concrete (CCIX)

www.compositeconstructionix.com/ ccix/index.html.en

Sheffield, UK 1–3 September 2021

Eurosteel 2021

www.eurosteel2020.com

Madrid, Spain 8–10 September 2021

Footbridge

www.footbridge2020.com

Stuttgart, Germany 5–7 October 2021

parts2clean

www.parts2clean.de

Bern, Switzerland 7 October 2021

Steelday+

steelday.ch

Karlsruhe, Germany 26–29 April 2022

PaintExpo

www.paintexpo.com

Aveiro, Portugal 14–16 September 2022

International Colloquium on Stability and Ductility of Steel Structures 2022

www.ua.pt/pt/sdss2022

00_STCO_0121_Buch.indb 71

Steel Construction 14 (2021), No. 1 71

03.02.21 11:17

Prof. Markus Knobloch, Prof. Ulrike Kuhlmann, Prof. Andreas Taras et al.

Structural member stability in the second generation of Eurocode 3 26 March 2021 10.00–12.00 a.m. CET With a series of Online Live Seminars (OLS) ECCS Steel Construction (STCO) journal presents international keynote speakers with up to date topics. Partner of the STCO OLS series is the European Convention for Constructional Steelworks (ECCS). The online lecture takes up to 1.5 hours. Following the speakers are available for questions and answers.

STCO OLS #2 will be given by Prof. Markus Knobloch, Ruhr-University Bochum, Prof. Ulrike Kuhlmann, Stuttgart University and Prof. Andreas Taras, ETH Zurich – supported by Anna-Lena Bours and Fabian Jörg – with a keynote Structural member stability in the second generation of Eurocode 3 at 26 March 2021 10.00 to 12.00 a.m. CET. The keynote is based on a two part paper by Knobloch, M.; Bureau, A.; Kuhlmann, U.; da Silva, L. S.; Snijder, H. H.; Taras, A.; Bours, A.-L.; Jörg, F. Structural member stability verification in the new Part 1-1 of the second generation of Eurocode 3,

Part 1: Evolution of Eurocodes, background to partial factors, cross-section classification and structural analysis (DOI 10.1002/ stco.202000016), Part 2: Member buckling design rules and further innovations. (DOI 10.1002/ stco.202000027), which had been published in Steel Construction 13 (2020) issues 2 and 3.

Registration www.ernst-und-sohn.de/stco-seminar

Fees 39 €* (regular) 29 €* (ECCS/national associations members)

www.ernst-und-sohn.de/stco-seminar * Excl. VAT. The General Terms and Conditions of the Akademie der Ingenieure apply.

STCO-OLS-2-Knobloch.indd 22 00_STCO_0121_Buch.indb 72

08.01.2021 12:03:46 03.02.21 11:17

Steel Construction – Design and Research The articles published in the journal are protected by copyright. All rights are reserved, particularly those of translation into foreign languages. No part of this journal may be reproduced in any form whatsoever without the written consent of the publisher. Brand-names or trademarks published in the journal are to be considered as protected under the terms of trademark protection legislation, even if they are not individually identified as such.

Manuscripts are to be sent to the editorial staff or http://mc.manuscriptcentral.com/stco.

If required, offprints or run-ons can be made of single articles. Requests should be sent to the publisher.

Current prices The journal “Steel Construction – Design and Research” comprises four issues per year. In addition to “Steel Construction – Design and Research print”, the PDF version “Steel Construction – Design and Research online” is available on subscription through the “Wiley Online Library” online service.

Prices

print

print + online

single issue

Institutional

655 €

819 €

174 €

Members of the ECCS – European Convention for Constructional Steelwork receive the journal Steel Construction as part of their mem­ bership.

Prices exclusive VAT and inclusive postage. Errors and omissions excepted. Subject to change without notice. Student prices, bulk prices and prices in other currencies on request.

Prices are valid from 1st September 2020 until 31st August 2021.

Personal subscriptions may not be sold to libraries nor used as library copies.

A subscription lasts for one year. It can be terminated in writing at any time with a period of notice of three months to the end of the subscription year. Otherwise, the subscription extends for a further year without written notification.

“Steel Construction – Design and Research”, ISSN 1867-0520, is published quarterly. US mailing agent: SPP, PO Box 437, Emigsville, PA 17318. Periodicals postage paid at Emigsville PA. Postmaster: Send all address changes to “Steel Construction – Design and Research”, John Wiley & Sons Inc., C/O The Sheridan Press, PO Box 465, Hanover, PA 17331.

Publisher Wilhelm Ernst & Sohn Verlag fur Architektur und technische Wissenschaften GmbH & Co. KG Rotherstrasse 21, 10245 Berlin, Germany Phone +49 30 47031-200, Fax +49 30 47031-270 info@ernst-und-sohn.de www.ernst-und-sohn.de Journal for ECCS members The ECCS – European Convention for Constructional Steelwork and Ernst & Sohn have agreed that from 2010 onwards Steel Construction is the official journal for ECCS members. www.steelconstruct.com Editor-in-chief Bernhard Hauke, Ernst & Sohn, ECCS Phone +49 160 97858589 bhauke@wiley.com

Scientific Board Frans Bijlaard, Technical University Delft Dinar Camotim, Instituto Superior Técnico Lisbon S. L. Chan, The Hong Kong Polytechnic University Paulo Cruz, University of Minho Jean François Demonceau, ECCS, University of Liege Dan Dubina, Polytechnic University Timisoara László Dunai, Budapest University Morgan Dundu, University of Johannesburg Markus Feldmann, ECCS, RWTH Aachen University Dan Frangopol, Lehigh University Leroy Gardner, Imperial College Jerome Hajjar, North Eastern University Jean-Pierre Jaspart, University of Liege Ulrike Kuhlmann, University of Stuttgart Jörg Lange, ECCS, Technical University Darmstadt Raffaele Landolfo, ECCS, University of Naples Guo-Qiang Li, Tongji University Richard Liew, National University of Singapore Enrique Mirambell, Polytechnic University of Catalunya Kim Rassmunsen, University of Sydney John Michael Rotter, The University of Edinburgh Peter Schaumann, ECCS, Leibniz University Hannover Bert Snijder, ECCS, Technical University Eindhoven Luís A. P. Simões da Silva, University of Coimbra Kunitomo Sugiura, Kyoto University Andreas Taras, ETH Zürich Thomas Ummenhofer, ECCS, Karlsruhe Institute of Technology Viorel Ungureanu, ECCS, Polytechnic University of Timisoara Ioannis Vayas, National Technical University Athens Milan Veljkovic, ECCS, Technical University Delft Pedro Vellasco, Rio de Janeiro State University Paulo Vila Real, ECCS, University de Aveiro František Wald, Czech Technical University Prague Riccardo Zandonini, University of Trento Industrial Board Alexander Britner, ECCS, KIT Center Steel Timber Masonry Véronique Dehan, European Convention Constructional Steelworks Mladen Lukic, ECCS, CTICM Koen Michielsen, Infosteel Belgium/Luxembourg Kjetil Myhre, ECCS, Norwegian Steel Association Till Vallée, Fraunhofer IFAM Olivier Vassart, ArcelorMittal Advertising sales manager Dominique Riedel, Ernst & Sohn Phone +49 30 47031-252, Fax -230 dominique.riedel@wiley.com Services for customers and readers Wiley-VCH Customer Service for Ernst & Sohn Boschstrasse 12, D-69469 Weinheim Tel.: +49 (0)800 1800 536 (Germany) Tel.: +44 (0)1865476721 (outside Germany) Fax: +49 (0)6201 606184 cs-germany@wiley.com Quicklink: www.wileycustomerhelp.com Layout and typesetting TypoDesign Hecker GmbH, Leimen Printing Westermann DRUCK | pva, Zwickau © 2021 Ernst & Sohn Verlag für Architektur und technische Wissenschaften GmbH & Co. KG, Berlin

Project Editor Giulia Fumagalli Phone +49 30 47031-269, Fax -410 giulia.fumagalli@wiley.com Editorial Board Véronique Dehan, European Convention Constructional Steelworks Prof. Markus Feldmann, ECCS, RWTH Aachen University Luís A. P. Simões da Silva, University of Coimbra Olivier Vassart, ArcelorMittal

Inserts in this issue: Verlag Ernst und Sohn, 10245 Berlin

Steel Construction 14 (2021), No. 1

00_STCO_0121_Buch.indb 7

03.02.21 11:17

Preview 2/21 Steel-concrete-steel composite (SCSC) plates are used for single-track, short-span railway bridges in transverse direction. The described simple framework engineering model including springs considers cyclic loading and inelastic slip. (Palotás, B. et al.)

Dheeraj Karki, Harry Far State of the art on composite cold-formed steel flooring systems Hassan Al-Karawi, Mohammad Al-Emrani The efficiency of HFMI-treatment and TIG-remelting in fatigue life extension of existing welded structures Peter Schaumann, Manuela Böhm, Karsten Schürmann Improvements in the fatigue design of support structures for offshore wind turbines Bálint Palotás, Patrik Takács, Josef Fink Simulation of a SCSC plate with a spring framework model including the effects of inelastic slip Damaso Dominguez, Gary S. Prinz Cyclic behavior of laterally skewed special moment frame connections having composite concrete slabs

(subject to change without notice)

Technical articles online available all Ernst & Sohn journals over 31,000 technical articles going back to 1967 easy research PDF download Tip: All Ernst & Sohn Special Issues in english can be found in the digital archive www.ernst-und-sohn.de/en/journal-articles 1155186_dp

1155186_dp_210x104mm.indd 00_STCO_0121_Buch.indb 8 1

31.05.17 11:17 12:25 03.02.21

Reprints – using your own publications as a marketing tool Reprints are an interesting marketing medium, not just for you but also for your business. The publication and distribution of special editions allows you to benefit from Ernst & Sohn‘s well-established reputation within your target audience.

By taking advantage of this image transfer opportunity for your business, you can maximize the accessibility of your work for:     For example: Festschrifts

the market your business partners your clients your colleagues.

We can provide you with reprints:    



of essays or reports, in combination with matching product pages, enhanced with your own texts and images, compiled from various periodicals/journals according to theme or project, also in digital format (PDF)...

For e

xam

ple:

Bro

chu

res

...for any occasion: anniversaries, corporate events or conferences, as a festschrift in book format,  we are also happy to produce a compilation of contributions from your books and journal articles.  

A digital version for your company website is always provided.

For example: Brochur

For further information see our website:

Ernst & Sohn Verlag für Architektur und technische Wissenschaften GmbH & Co. KG

Sonderdrucke_210x297mm_EN.indd 1 00_STCO_0121_Buch.indb 3

Anything is possible – we will be pleased to advise you.

www.ernst-und-sohn.de/en/reprints

Rotherstraße 21 D-10245 Berlin phone: +49 (0)30 470 31-292

1138116_pf

16.05.2017 11:15:32 03.02.21 11:17

Structural Protection Systems © KSP Jürgen Engel Archtitekten, Krebs & Kiefer International

STRUCTURAL BEARINGS | EXPANSION JOINTS | SEISMIC DEVICES | VIBRATION ABSORBERS | MONITORING

BAKU TOWER, AZERBAIJAN Job Description: Vibration damping of the 277 m high Baku Tower and Seismic Protection of the structure to ensure living and working comfort.

MOSQUE ALGIERS, ALGERIA Job Description: The third biggest mosque in the world requires an innovative seismic protection, with a design life of 500 years.

DANUBE CITY TOWER, AUSTRIA Job Description: Reduction of the horizontal acceleration of the structure caused by wind and earthquake at a high rise building of 220 m height, to generate sufficient comfort.

SOCAR TOWER, AZERBAIJAN Job Description: Prevention of horizontal accelerations of the flameshaped 200 m high structure, caused by wind and earthquake.

Project scope: One MAURER Tuned Mass Damper (TMD) with 400 ton steel-concrete mass and 10 MAURER Hydraulic Dampers MHD.

Project scope: 246 nos. sliding isolation pendulum bearings SIP with a rotational hinge (design specification 3 % dynamic friction and 2,400 mm effetive radius), as well as 80 nos. MAURER Hydraulic Dampers MHD with a response force of 2,500 kN.

Project scope: Two MAURER adaptive hydraulic dampers with a response force of up to 80 kN and +/– 700 mm stroke, which dampen the 300 ton mass-pendulum. Including a monitoring system for displacements, forces and accelerations.

Project scope: One MAURER Tuned Mass Damper MTMD with a mass of 450 ton, plus MAURER Hydraulic Dampers MHD which dampen at 0.32 Hz and a stroke of +/– 400 mm. Including a monitoring system for displacements, forces and accelerations.

MAURER SE | Frankfurter Ring 193 | 80807 Munich/Germany Phone +49.89.323 94-0 | Fax +49.89.323 94-306 | www.maurer.eu

Anz_Leistungsspektrum_2020_A4_EN--ISOcV2.indd 1 00_STCO_0121_Buch.indb 4

forces in motion

16.10.20 11:37 03.02.21 11:17