Introduction to Grid shell construction technology, using wood and concrete

1. GRID SHELL
Sahil Ahmed - 01
Ishwar Bhat - 04
Utsav Chaudhury - 09
Dolly Gada - 17
Jahnavi Joshi - 22

2. Introduction:
A shell is a natural, extremely strong three dimensional structure, that resists applied loads through its inherent
shape. There are a several forms of structure that belong to this group of load bearing structures, which carry
applied loads mainly by way of membrane forces.
Key features of a Grid Shell structure:
● Tri-dimensional surfaces
● Self supported structures, no additional frames or columns required
● Resist load with geometry

3. Construction Scheme
Source:http://bepls.com/splissue2015/4f.pdf

4. Classification of Gridshell:
● A gridshell may be made of different geometric modules. But the most used modules as the basic patterns are
included, square, diamond, triangular and hexagonal grid. Triangular format geometry is of the inherent stability.
Gridshells facilitate development in three directions:
1) Reuse of historic buildings with appropriate functions,
2) Materials can save up to 50% compared with conventional frame structures and ability to be build structures
with different materials
3) Greater amounts of natural light enter the building
● Any curved surface with very low depth to span ratio may be regarded as a gridshell.
Gridshells may be classified in terms of :
1. Geometry of the grid
2. Type of Load transfer
3. Form

5. ● Grid pattern replaces the shell material which enables the overall structure to benefit from the combined action of
shell and arches, thus can achieve unique shapes.
● Gain stability from their geometric shape
● Internal forces are carried by members and therefore have to follow a restricted number of paths.
● A plain, continuous shell can resist normal and shear forces while the lattice shell can resist forces in the direction
of the axial forces
Grid Geometry
Source:http://bepls.com/splissue2015/4f.pdf

6. ● Feature of grid structures is their ability in two or more way load transfer.
● The system transfers loads from multiple directions and hence can be classified as two - way, three - way
and four - way grids.
Types of Load Transfer
Source:http://bepls.com/splissue2015/4f.pdf

7. Grid shells can be divided into different categories according to structure:
1. Curved in one direction : Cylindrical Shells:
2. Two- directional shells : All kinds of domes
3. Shells with curvatures in opposite direction
4. Shells with free - form curved surface
Form
Source:http://bepls.com/splissue2015/4f.pdf

8. 1. The common structures for gridshell are made of timber, which can be bent elastically without breaking. Timber is
used due to low-density and high strain range.
2. Timber gridshells are of spatial structures and combine structural efficiency with a pleasant appearance.
3. They are used in temporary buildings such as temporary exhibitions, or when rapid construction is concerned, can
be customized.
4. Fiber glass reinforced polymer materials also can be used in the system. Fiber glass reinforced polymer materials
have greater stiffness than timber and thus, for a given geometry of the gridshell.
5. However, fiberglass reinforced and composite materials can be considered as an alternative to timber members.
Material
Source:http://bepls.com/splissue2015/4f.pdf

9. 1. Joints in the structure should not only join the members to each other, but should provide rotations while
maintaining the geometry of the grid.
2. The ability of the nodes rotations is the unique characteristics of the structure and provides the possibility of
building free and complex forms.
3. It is well known that the nodes are of critical points of the structure and their design requires a high level of
creativity and innovation.
4. However, two types of nodes that are typically used in these structures are slot node and plate node.
Joints
Source:http://bepls.com/splissue2015/4f.pdf

10. Advantages & Disadvantages of Grid Shells
● The benefits of using a grid shell compared to either the conventional slab and frame system or the continuous
shell are both aesthetic and structural.
● The curved shapes often used for concrete shells are naturally strong structures.
● Shell allowing wide areas to be spanned without the use of internal supports, giving an open, unobstructed
interior.
● As concrete is relatively inexpensive and easily cast into compound curves
However, there are a few stability failure on gridshell structures including:
● Members buckling means a member buckling without influence on the rest of the structure
● Local instability, meaning the failure of one or more nodes
● Global instability, meaning the structure buckles as a whole.
Source:https://www.slideshare.net/SusmitaPaul12/shell-structure

11. Case Study - Mannheim Multihalle by Frei Otto
● Frei Otto, developed the concept of gridshells.
● Funicular geometry modelling.
● In 1970 this technique was used to construct a 9000
sqm curved roof structure from 5 cm square timber
laths.
● 20 m highest point in the structure.
● Widest span is 60m.
● Length of the structure is 85 m.
Source:https://www.sciencedirect.com/science/article/pii/S2
214399815300011

12. ● Multipurpose hall building was to be the
central feature arranged alongside a through
route and with a restaurant on the other side.
● Using an equal mesh square grid of timber
laths or steel rods thin enough to be readily
bent into shape.
● A square grid can be moulded to a doubly
curved surface by the deformation of the grid
squares into a rhombi. Such a structure Otto
described as a gridshell
Source:https://www.sciencedirect.com/science/article/pii/S2
214399815300011

13. ● Prestressed tensioned surfaces have to adopt an
equilibrium geometry in which the tensile forces in two
directions are balanced.
● The perfect representation of this is a soap film in which
the surface tensions are the same in all directions but they
are difficult to measure. This forms a “minimal” surface
and is a good starting point for a surface tensioned
structure.
● Otto’s modelling process would often start with soap film
models and then move on to more robust stretch fabric
models from which he would develop the fabric patterns
using strips of paper.
● Hookean principle ?
Trial timber structure
(15 m × 15 m super-elliptical plan. The grids were clad
with thin plywood sheets to form the enclosures.)
Source:https://www.sciencedirect.com/science/article/pii/S2
214399815300011

14. ● The ends of the link lines were connected to the
boundary line with small springs that could be
adjusted to achieve a reasonably uniform tension in
the grid. Without such springs it is very difficult to
get the forces reasonably well shared between the
two directions of the grid.
● The form of the shells had been developed by
hanging chain models so theoretically the
self-weight loads would produce only compression
forces in the laths
Final Hanging chain model for Mannheim.
Source:https://www.sciencedirect.com/science/article/pii/S2
214399815300011

15. Timber lath cross junction
joineries
Ground connection detail
TImber lath cross joinery with
steel rod braces

16. Case Study - Temporary cathedral by ATELIER
D'INGÉNIERIE
● Designed as a temporary cathedral.
● Made of composite materials: Glass fiber reinforced
polymer tubes (GFRP), covered by a PVC coated
fabric.
● It weighs 5 kg/sqm and Area of 350sqm.
● Height - 7m.
● Span - 17m.
● Length - 29m.
Source : https://www.tess.fr/en

17. ● A circular seating arrangement is often
considered the most convivial
● The final form is based loosely on two
adjacent semi spherical volumes of different
size, which are merged into one complex
form.
● It was therefore decided that the two
spherical virtual forms, which would be joined
to make the final form, would be arranged
not in a asymmetrical axial manner.
Source : https://www.tess.fr/en
Form of the building

18. Construction details
● A regular planar grid made of long
continuous linear members is built on the
ground (Fig. 1).
● The elements are pinned together so the
grid has no in plane shear stiffness and can
accommodate large-scale deformations
during erection (Fig. 2).
● Then, the grid is bent elastically to its final
shape (Fig. 3).
● Finally, the grid is frozen in the desired
shape with a third layer of bracing members
(Fig. 4) and the structure becomes a shell.
Source : https://www.tess.fr/en

19. Construction details
One can identify 4 major structural details:
● a) The swivel coupler for connecting
composite pipes to assemble the grid
● b) The steel sleeve for connecting several
composite pipes to make long members
from initially short piece of tubes
● c) Ground anchorages for fixing the
structure to the concrete slab
● d) The lacing edge beam of the fabric
Source : https://www.tess.fr/en

20. Case Study: Centre Pompidou-Metz
Architects: Shigeru Ban Architects; Area: 11330 m²; Year: 2010
Building Function:
1.The main purpose for this annex to the Centre Pompidou was to be
able to show more works to the public
2.To be able to display the very large works that cannot be shown in
the Paris museum due to the 5.5m ceiling height under the beams.
3. The main purpose for this annex to the Centre Pom To
accommodate this requirement, 18m was maintained as the highest
ceiling height under the Grand Nef Gallery.

21. Roof:
1.The undulating laminated timber roof structure surrounds a
77-metre metal spire. The roof, inspired by a woven chinese hat.
2.The structure is made from highly resistant glue-laminated wood,
providing a mesh that can span lengths of about 40 metres.
3. Total there are 1800 individual beams with no one being the
same. when all beams are laid out flatly in a line they measure to be
15 km in length. Highest point the roof reaches up to 77 meters.
This waterproof material creates a naturally temperate
environment, helping satisfy the building’s demanding energy
requirements and ensuring that works of art are exposed and
conserved in the best possible conditions.

22. Source:https://www.archdaily.com/490141/centre-pompidou-metz-
shigeru-ban-architects?ad_source=search&ad_medium=search_result
_all

23. Thank you