Shell structures are lightweight curved constructions made of thin shell elements like plates. There are different types of shell structures including concrete shell structures formed as domes or bridges, lattice shell structures like geodesic domes, and membrane structures made of fabric or tensile materials. Shells can be non-developable surfaces that are doubly curved, like synclastic domes with similar curvature, or anticlastic surfaces with opposite curvature. Developable barrel shells have a single curvature and act like beams. Shell structures provide advantages of light weight and large spans but also challenges with formwork accuracy.

1. SHELL STRUCTURE
HARSHIT JAIN

2. WHAT IS SHELL STRUCTURES?
Shell structure are light weight construction using shell elements, this elements are typically curved,
are called as plate structures. Only difference between this two are plate structures are flat and shell
structures are curved or shell like structures.

3. TYPES OF SHELL STRUCTURE
Concrete shell structures, often cast as
a monolithic dome or stressed ribbon
bridge or saddle roof.
Lattice shell structures, also called grid
shell structures, often in the form of a geodesic
dome or a hyperboloid structure.
Membrane structures, which include fabric
structures and other tensile structures, cable
domes, and pneumatic structures.
The European Centre | Adan Martin Auditoria de Tenerife
Valencia city Spain

4. • Plastics
Materials
• Aluminium • Steel
• Reinforced concrete
• Glass
• Timber

5. • CONCRETE SHELL STRUCTURES
A shell is a thin structure composed of
curved sheets of materials, so that the
curvature plays an important role in the
structural behaviour, realizing a spatial form.
A thin curved membrane or slab usually of
reinforced concrete that functions both as
structure and covering.
A grid shell is a structure which derives its strength
from its double curvature (in a similar way that a
fabric structure derives strength from double
curvature), but is constructed of a grid or lattice.
• Lattice shell structures

6. Non Developable surface : Doubly curved
They are mainly classified as :
1) Synclastic
2) Anticlastic
SYNCLASTIC
These shells are doubly curved and have a similar curvature in each
direction. e.g. domes.
Structural behaviour :
Similar to arches under a uniform loading the dome is under
compression everywhere, and the stresses act along the arch
and hoop lines
Are doubly curved but each of the two curves have the
opposite direction to the other. e.g. saddle points. shell
roofs, have compression stresses following the convex
curvature and the tension stresses follow the concave
curvature. ANTICLASTIC
Anticlastic shells

7. Construction of shell structures
The construction of a reinforced concrete shell involves.
• The design and construction of forms.
• Reinforcement selection and placing.
• concrete materials and placing.
• curing and decentring.
All of these problems must be understood in order to
make the structure safe and economically feasible.

8. Developable surface is a surface that can be unrolled
onto a flat plane without tearing or stretching it. It is
formed by bending a flat plane, the most typical shape
of a developable shell is a barrel, and a barrel shell is
curved only in one direction.
Arch action & beam action together make a barrel.
there are mainly two types of barrel :
• Structural behaviour of short barrel shells: These
shells are typically supported at the corners and can
behave in one or a combination of ways.
• Structural behaviour of long barrel shells: these
are typically supported at the corners and behave
structurally as a large beam.
Developable surface : Singly curved

9. Barrel vaults

10. BARREL VAULT

12. Advantages of Shell Structure :
• Very light form of construction.
• Useful for large span with small thickness.
• Dead load can be reduced by economizing
foundation and supporting system.
• Aesthetically looks good other forms of
construction.
Disadvantages of Shell Structure :
• Shuttering/ formwork problems
• Greater accuracy in formwork is needed.
• Skilled labour and supervision are required.
• Rise of roof may be a disadvantage.

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