22 HORS SERIE #017 | REVUE TECHNIQUE LUXEMBOURGEOISE
In summer 2016, two devastating earthquakes hit central Italy. The principle cause of deaths and injuries was not the earthquake itself but the destruction of a high number of buildings and roads as a consequence of seismic action. Thus, the major objective is to design structures that are able to absorb the released energy to limit any collapse of buildings where possible. The economic damage, as well as the loss of lives, should make engineers think of how to design structures that resist the damage caused by such natural hazards.
Prix d´excellence 2019
SEISMIC PERFORMANCE EVALUATION OF STEEL MRFS DESIGNED WITH PREQUALIFIED BEAM-TO-COLUMN CONNECTIONS IN EUROPE_
Doc. ID: ANNEX II to D-W
Claire Kox
European pre-qualified steel joints (EQUALJOIN Grant agreement no. RFSR-CT-2013-0
9
60
160
60
95 55
Ø3
210 55 95
250
210
380
1100 600
In Europe, “no reliable design tools exist to be able to predict the seismic performance of dissipative beam-tocolumn connections in order to meet code requirements” (Landolfo, 2013) and seismic building design is based on Eurocode 8. Hence, a research project, called the “European pre-QUALified steel JOINTS” (EQUALJOINTS), was put in place in order to compensate this missing part of EN1998-1. Its focus is on the introduction and standardization of design and manufacturing procedures in order for engineers to easily implement joints in steel structures.
15
280
15
In the framework of this study, the stiffened extended endplate beam-to-column connection (Figure 1) was analysed and implemented in a prototype building to Design Criteria evaluate its seismic behaviour.
295
250
30
250
ES3 – TS - F
American and European Beam-to-Column Connections It was the Northridge earthquake, on the 17th of January 1994 that contributed to major changes in designing steel structures and especially beam-to-column connections in the United States. The buildings sustained severe damage, often brittle failures of the welded moment-resisting connections. Thus, in order to avoid such brittle failures and improve the structures’ ductility, an American standard that “specifies design, detailing, fabrication and quality criteria for connections that are prequalified” was put in place.
Full Strength
Sini,j (kNm/rad)
Beam Section Sj (kNm/rad) IPE600 Design Limitations According to AISC and EQUALJOINTS Project HEB500 EIb/Lb (kNm/rad) A good ductile design against seismic loads Column enablessection the energy to be dissipated through plastic hinge regions that Bolt size M36 K (-) occur at some distance from the column faces through a flexural hinge at the beam’s extremities andEnd-plate at the column thickness 30mm β (bolt row 1) base. In order to achieve a ductile design, one should first make sure that the steel cross-sections are section class 1 Mp,beam (kNm) 1246.90 η (bolt row 1) or 2, meaning the more the cross section is able to rotate, (kNm) _Fig. 1: Stiffened2233.79 β (boltconnection row 2) the more it shows a ductile behavior. Moreover, M the beam’s extended end-plate beam-to-column p,con EQUAULJoint vs. typical beam-to-column connection before 1994 span-to-depth ratio is limited according to the behavior Mp,wp (kNm) Thus, in the case 2906.1 (bolt rowbeam 2) depth, factor q (Table 1) and finally the cross section parameters of DCM (q ≤ 4), forη the same are limited. the American code allows a smaller span length compared Mp,j/ MEd (bolt 3) 1.07 to the one that was tested in EU.βOn therow contrary, for a On the one hand, one should limit the width of bays in DCH design (q > 4) the American code allows a slightly MRFs, as long spans contribute to a more flexibleMbehavior. 1.39 η (bolt row 3) p,wp/ MEd bigger spans compared to the spans tested in Europe. Consequently the cross-section sizes have to be increased Consequently, the choice of cross-section with regard to control drift. On the other hand, short spans should also to span length is more limited in Europe than it is in the be avoided because they tend to yield in shear but and one United States. prefers flexural yielding of beams. The measurements depend on whether the building will be Comparing the different parametric limitations on designed for a ductility class high (DCH) or medium (DCM). prequalification, it was observed that the upper bound
708668 495829 61389 11.54 0.73 0.71 0.56 0.56 1.08 0.79