Shallow masonary dome

Shallow Masonary dome

BMC-IX | Ipsa - Rajkot Guided by - Prof. Hitesh Changela | Ar. Anuj DaraniA | Hasu sir A0319_Shivam B. | A1519_Ritu K. | B4219_Vedanshee D. | B4819_Kush K

Preface This paper presents the study on shallow masonary dome construction techniques and it's execution methods and learnings. It shows how this construction technique is economical as well as structurally efficient in replacement of concrete slabs or other conventional methods.

This paper is primarily addressed to educators as well as students of architecture. An understanding and learnings of this technique, as one of the means to construct alternative of slab, will help them provide for better solution to address their design problem in innovative manner and cost saving parameters.

Grateful acknowledgement is here made to those who helped and guided this group during site work, and various faculties for their invaluable advice. We are indebted to Prof. Hitesh changela and Anuj Darania for their constant support during on-site work and letting us to held our head high after failures. Also thanks to Hasmukh Gajjar sir for his support in this research. Also seniors from batch 18 support for letting us experimenting in their already made metal frame is acknowledged. This work would not have reached it's present form without their invaluable help.

Content

1

Defination

2

History • • • • • • • •

3

Primary Case study -Funicular shell • • • • • •

4

Development of masnory vaults Understanding Dieste’s work Rafael guastavino and graphic statics Eladio dieste and masonry vaulting Torroja and Dieste - Structural forms Freyssinet and Dieste - Thin shells and thin ties Maillart and Dieste - Vault as cantilever beam Isler and Dieste - New shell forms

History & context Material Structural Analysis Components Construction Advantages

Final Proposal • Shallow dome with formwork • Shallow dome without formwork

5

Expenses breakdown

6

References

Defination Shallow masonry or funicular shell construction is indeed an interesting and traditional technique used in many regions, especially in parts of India, where resources like concrete might be limited. It involves using a layer of bricks laid on edge, which can serve as an alternative to a concrete slab for roofing systems. Here are some key points to consider about this construction method: Brick on Edge: In this construction technique, bricks are laid flat on their sides, so they form an archlike structure.

Two Methods: There are two common methods for building funicular shells: With Formwork: In this approach, temporary wooden or metal formwork is used to shape the shell structure. The bricks are laid on the formwork, and then the structure is reinforced and finished.

Without Formwork: This method involves laying bricks directly on top of one another without the use of formwork. A mortar mixture, typically consisting of a 1:2 ratio of cement to sand with a small proportion of soil (about 1/4th), is used to bind the bricks together. The soil acts as a sticky material and cohesive binder.

Structural Efficiency: Funicular shells are considered structurally efficient because they rely on the fundamental arch action, which distributes loads efficiently. This arch action makes the shell capable of bearing substantial loads.

Catenary Shell: The funicular shell is often designed in the shape of a catenary, which is a type of curve formed by a hanging chain. The catenary shape provides inherent structural stability and minimizes the need for additional structural elements.

Resource Utilization: This construction method is particularly practical in regions where resources such as soil, bricks, and manual labor are readily available. It is an excellent example of utilizing local materials and traditional knowledge for sustainable construction.

Roofing System: Funicular shells are often used as roofing systems, providing shelter and protection from the elements. Their design allows for open and spacious interiors without the need for supporting columns or beams.

Fig.1 Shallow masnory dome

History Development of masonry vaults

European • •

Roman, Gothic and Renaissance vaulting Thick vaults, resisted with buttresses

Fig.2 Ribbed Vault

Middle east •

Barrel vaults and domes without use of centering and thick vaults supported with thick walls

Fig.3 Barrel Vault

Catalan • • •

Fig.4 Catalan Vault

Emerged in barcelona, multiple overlapping of thin tiles.

Thinner and lighter than other two Shallower, extremely strong due to staggering of joints. Also referred as timbrel vaults.

Understanding Dieste’s work Introduction Eladio dieste is an urguayan engineer and architect who designed emotionally moving spaces creatively using reinforced brick shells.

During the transculturation in latin american countries, whose architecture has undergone a strong influence from european design principles. Eladio dieste understood that the elements to define latin american architecture lie from it’s distinct national resources of regional materials and use of construction methods.

He believes “the ones who invent are the one who rule.”

Motivated him to soon become known as a principle builder for his mastery of “reinforced masonary”.

Fig.5 Eladio Dieste

The two revolutions 1. Rafael guastavino and graphic statics (1842-1908) 2. Eladio dieste and masonry vaulting Felix Candela(1910-97) and Eduardo Torroja(1899-1961) were enjoying worldwide fame for their sleek shell structures made of reinforced concrete.

Works of Gustavino, Eiffel, Gaudi and Maillart, were all the structures that worked in pure compression and designed through graphic statics. But by the time of Eladio Dieste, it was falling gradually into disuse, because numerical methods were becoming the norm.

Fig.6 Los Manantiales by Felix Candela

Fig.7 City hall loop station by Rafael Gustavino

Torroja and Dieste - Structural forms • • •

Thin brick timbrel vaults of the type constructed by Gustavino played a role in development of both engineer’s work, Eduardo Torroja in spain and Eladio Dieste in uruguay.

Torroja was nearing to the end of his career, while dieste was entering the early stages of his career.

Thin concrete shells use extensive formwork, costly to build, hence reinforced brick came as an economical alternative.

Fig.9 Church of Christ , By Dieste Fig.8 Church of Pont Du Suert , By Torroja

Freyssinet and Dieste - Thin shells and thin ties • • • •

Freyssinet developed the concept of prestressed concrete.

Dieste designed many buildings similar to Freyssinet. Steel tension ties resist the thrust of the vaults, and glazing admits the light between repeating shells.

Formwork is reused from bay to bay.

Brick shells acts as an arch and the undulating cross section provides resistance to asymmetrical loading and to buckling.

Fig.10 Railway repair shop, by Freyssinet Fig.11 Port warehouse by Dieste

Maillart and Dieste - Vault as cantilever beam • • • •

Dieste’s structure is a barrel vault that acts as both a thin shell and cantilever beam.

At each end, thrust if vault is resisted by a tapered horizontal edge bea, supported on diagonally braced reinforced concrete column.

Dieste’s vaults take catenary form in cross section while Maillart’s vault resembles a parabola.

Dieste used post tensioning while Maillart used reinforced concrete only.

Fig.12 Cement Hall by Maillart

Fig.13 Massaro agroindustries by Dieste

Isler and Dieste - New shell forms • • •

The principal difference between Isler’s tennis center and Dieste’s horizontal silo designs is the type of loading.

Incase of Isler’s shells, the dominant load is vertical and in silo structure, dominant load is horizontal, created by the thrust of grains or salt inside the silo, which must be resisted by the walls.

Cross section of horizontal silo is a catenary, where as isler’s shell will function in pure compression under vertical load of its own weight.

Fig.14 Heimberg Tennis center by Isler

Fig.15 Silo by Dieste

Primary case study - Funicular shell History and Context The construction of masonry domes and vaults with formwork started together in India. However, the use of domes and vaults became popular during the reign of the Mughals. The building technique started parallel in the north with the construction of Qutub Complex in Delhi and the buildings of the Bahamani Kingdom in the south. The technique of masonry shallow domes also developed along the lines of other domes and vaults.

Case of Muzzafarnagar: The oldest shallow dome found in western Uttar Pradesh and Haryana is around 400 years old, built in lakhauri bricks with lime mortar. The rise of the dome varies from 9 inches to 2 feet. A team from Hunnarshala visited this building during the rehabilitation of the riots affected people of Muzzaffarnagar. Nawab, a house owner in the rehabilitation program and an artisan who specializes in the construction of shallow domes introduced the technique of building these domes.The technique has gone through several changes through the time, as new materials like cement and steel gained recognitions, which impacted the aspirations of the people. The general aspirations tilted towards having at roofs. The artisans were able to reduce the rise by using ties and also reduce the thickness of the wall required by using a ring beam.

Rohtak dome: The method of building shallow dome i.e. funicular shell was originated in south america and it continued in most of the regions in south america. The construction of Rohtak dome is heavily skill dependent and in india it is limited to a small team of masons lead by Azad singh whose father learnt this technique from Rishi dilip lal birju from kathal gaam and passed it on to his kin as a family tradition.

This skill has been practiced and honed for 40 years

Fig.16 Laying of bricks on formwork

Current Practices There are two types of shallow masonry domes, which are presently built in western U.P. and Haryana, one with shuttering and one without shuttering are used to build these domes. In the villages of Uttar Pradesh, the masons use shuttering method for building the domes and produces variations in the dome using the same. Nawab, an artisan from the same region makes dome with formwork and pours concrete in the joints. In Haryana, the artisan’s building method differs. Narayan (team member of azad singh), and his family make shallow domes without shuttering with rich cement mortar.

Today, all these masons and artisans are being called in various regions of india for making these shallow masonary domes, one can see majority of the works done by azad and his team in surya kakani’s work and domes with formwork done by hunnarshala foundation.

Material

Fig.17 Tools and materials used for shallow dome

Structural Analysis

de ta i ls

Plan of the training hall, indicating the grid of Edge Beams

B

ea

m

ty

pe

Beam type A

6’9”

B

Beam type D Beam type C

Funicular Shell arrangement for a hall of size 20’ by 20’.

The roof has been divided into smaller spans with a grid of beams (as shown in the sketch). 3 shapes of funicular shells have been used in the roof

4’2”

21’6”

Beam type B

4’

21’ 6”

Fig.18 Load distribution in Rohtak dome Cross sections of Edge Beams

5 No 12 mm

2 No 10 mm 2 No 16 mm

Type A

Type C

Type B

Type D

Funicular shell is a three dimensional catenary shell on rectilinear base, acts on the fundamental of 5 No 10 mm 3 No 16 mm arch action, having good load bearing capacity and compressive strength using waste stone pieces 3 No 16 mm 4 No 16 mm Triangulated and brickbats, supported on the concrete edge beam. stiffeners to be provided on all 4 faces of the beam

Brick 3” thick 1.5” Thick cement concrete 1:2:4

Section of Funicular Shell Steel beam 9’’x9’’

of funicular shell cons Fig.19 tru cCross-section ti on

Pointing done in lime surkhi mortar (1:3:8) Level to which beams are partially cast before laying the funicular shell

Components Edge beam The upper half of the edge beam is required to hold the stirrups. It is cast along with the funicular shell; therefore, it can also be a triangular section.

A skylight can be introduced in the roof. This can be achieved by leaving a hollow while casting, de ta i ls using the inherent strength of a ring in compression.

Funicular Shell 1”-3”. Thus, the beam also The edge beam can be given a slight camber or lift in the centre, about 6’9” arrangement for a hall of acts as an arch, comes under compression, further increasing size its 20’ load by 20’.bearing capacity. This also B ea Thein roof been divided m reduces the amount of steel and cement consumed thehas beam. ty

pe into smaller spans with a B grid of beams (as shown in Alternatively, the beam can be partially precast, in which case3ashapes pre welded reinforcement cage the sketch). of Beamis type D funicular shells have been placed along the grid and cast half. used in the roof 4’2”

The cage is fabricated as truss girder improving loadPlan bearing capacity and reducing beam section. of the training hall, indicating the grid of Edge Beams

Beam ty

4’

21’ 6”

a i ls

ning hall, e grid of e Beams

i on

Allows ample flexibility in design- funicular shells can take any shap 5 No 12 triangular or trapezoidal

Cross sections of Uses locally available waste stone, normally available from stone c Edge Beams

B

ea

m

ty

pe

Beam type A

6’9”

B

Beam type D Beam type C

ar Shell a hall of ’ by 20’. divided s with a shown in hapes of ve been the roof

4’2”

For construction above the intermediate floor, theType funicular roof pro A walls since the load distribution is uniform because of arch action o

5 No 10

21’6”

Design of the funicular roof can be very well adapted to seismic de

Finishes like plasterTriangulated and paint for the roof are not needed 3 No 16

stiffeners to be Being a labour intensive technology, leads to employment generati

Type B

provided on all

Simple technology which easily 4 facescan of the beambe adapted by semi-skilled lab

The funicular roof is aesthetically much better than other roofs – va made using brick and stone

Beam type B

Fig.21 Cross-section of Edge beam

4’

Funicular Shell

21’ 6”

Fig.20 Plan of Edge beam 5 No 12 mm

Section of Funicular Shell 2 No 10 mm

Profile

Clear span

2 No 16 mm

:

Bri

1.5 con

Doubly curved For any desired plan shape various points can be calc Pointing done in 6332 surkhi mortar (1

Steel beam

: 9’’x9’’ 3’ to 9’ to which This defines aLevel range of spa beams are parti Bigger spans before upto 40’ arethe a laying design funicular shell

Funicular Shell Type A Type C Shape : A variety of shapes are pos The entire area to be roofed ismmdivided into3 No a 16grid 5 No 10 mm depending on the size of the funicular shell required triangular to suit the dim c o n s t r u c t i o n or the size / shape of moulds The optimal span of the 3 No 16 available. mm 4 Norise 16 mm to span ratio is 1:6, thus the Rise at centre : One sixth of the clear span Triangulated 6” to 18” ( for 3’-9’ spans) stiffenersis to be shell 3 m thoughType it can span up to 15 m.

The mould is supported between the edge beams.

Timber B Type D provided on all Shell material : Broken stone 4 faces of the beamused to bridge the gap between the edge of the mould and the edge beam. The shell pieces of 1”-2 planks are (for a masonry shell) Brick tiles (1.5”-2”) of at lea comprises of the materials – bricks, stone waste – laid in the funicular profile topped with compressive strength Brick 3” thick Reinforcement : No reinforcement is neede cement-sand mortar and concrete screed.

Topping mortar

1.5” Thick cement concrete 1:2:4

Edge Beam

Reinforcement:

:

Rich cement-sand mortar o

A pre-welded beam with tri

with 6 mm bars (as shown Concrete In-fill (cast as a Pointing done in lime designed as per span grid of beams) After the shells have surkhi been cast, mortar (1:3:8) the valley spaces which are formed between the shells can be filled Steel beam Cross section : 9” x 9” (for a 9” thick mason 9’’x9’’ Level tolike which brick jelly lime concrete and finished flat. The infill will enable the with light-weight material Concrete mix : M 20 in-situ concrete for t beams are partially cast between adjacent shells construction of an intermediate before laying the floor which can be used to build above.. funicular shell

Construction

Fig.22 Construction process of shallow dome

• • • • •

Clear span range - 3’ - 9’ for normal applications.

Rise to span - 1:12 ratio i.e. 3 feet span will have rise of 4 inch and 9 feet span will have 12” rise in the centre.

Shape - variety of shapes are possible including square, rectangle and triangle guiding the grid of the floor/slab.

Topping mortar - rich cement sand mortar of 1:2 ratio over masonry shell.

Reinforcement - no reinforcement is required in masonry funicular shell.

Advantages • • • • • •

Eliminate use of steel reinforcement.

Allows efficient use of waste materials.

Minimises requirement of internal plasters.

Provides roofing at a lower cost.

Since it acts as an arch, it takes load in compression and distributes it equally in all directions.

Artistic patterns can be created in the ceiling.

Final Proposal Experiment -1 (Shallow dome with formwork)

Intention Intention of this experiment was to study how the bricks are laid on the formwork by creating some pattern and still resist the load given on the top of it. It can be tested in a week or two.

Funicular shell Specification • • • • • • •

Profile : Doubly curved Clear span : 3’ to 9’ Shape : Circular Rise at centre : 4’’ Shell material : Brick Reinforcement : No reinforcement is needed in a masonry funicular shell Topping mortar : Rich cement-sand mortar of 1:3 ratio over the masonry shell

Edge beam Specification •

Frame : Metal box frame of 1.7m in dia.

Fig.23 Metal frame Plan & Section

Shallow dome Inquiry Material Binding Agent Form Formwork Result

Final scaled sample Brick Cement mortar Shallow dome Waste infill Unccessful

Fig.24 Circular metal frame

Fig.25 Bricks laid on side to cover up the surface acting as a beam

Fig.26 Formwork of plywood is laid

Fig.27 Waste infill on the formwork

Fig.28 Marking the oculus and leveling the sand layer

Fig.29 Arranging brick on edge

Fig.30 Creating pattern

Fig.31 Dome is ready and curing to be done

Fig.32 Removing of formwork

Fig.33 Learnings from the failure

Fig.34 Testing the dome by putting weight

Fig.35 Learnings from the failure

Conclusion The diagonal arranged bricks are supposed to be placed when the diameter is too big. In this case 1.7 meter diameter is not sufficient to hold the one layer of diagonal brick.

Another reason of failure is the bricks forming the beam, as one of those bricks moves because of thrust, the whole beam went into the failure and dome collapsed.

Final Proposal Experiment -2 (Shallow dome without formwork)

Intention Intention of this experiment was to understand what makes this brick hold without the formwork. The mortar with soil and fine particles binds the brick and how the mortar with more water can play it’s role where brick sucks water off the mortar and holds the brick.

Funicular shell Specification • • • • • • •

Profile : Doubly curved Clear span : 3m / 9’ Shape : Square base Rise at centre : 12’’ Shell material : Brick Reinforcement : No reinforcement is needed in a masonry funicular shell Topping mortar : Rich cement-sand mortar of 1:2 ratio and 1/4 of sand over the masonry shell

Edge beam Specification Frame : 5mm thick L mild steel channel

50 [2"]

[1 3'

-5

"]

3000 [9'-10"]

41 00

•

50 [2"]

Fig.37 Metal frame Plan

Fig.36 Metal frame Plan

Shallow dome Inquiry Material Binding Agent Form Formwork Result

Final scaled sample Brick Cement mortar Shallow dome No formwork Work in progress

Fig.38 Process of laying bricks without formwork i.e. rohtak dome, where corners are made first till the first ring completes.

Breakdown of Expenses

Materials used Brick - 200 bricks Cement - 50 kg Sand - 125 kg sand 3x3 m L channel frame - 79.1 kg Metal frame (L angle + labour) - 7314 /Brick - 1600 /Transportation - 700/Sand - 600/Cement - 400/Total - 10,614/-

References https://www.scribd.com/document/47078101/Funicular-Shells# http://basinsa.net/training_menual/Funniculars%20Shell%20Roof.pdf http://www.hunnarshala.org/shallow-domes.html https://architecture.live/the-shallow-masonry-domes-alternative-traditions-in-roofing-systems-by-hunnarshala-foundation/ Alternative flooring techniques by Prof. Hitesh Changela