Shell roof

Shell roofs are made from structural ‘skins’ where the shell material is thin in section relative to the other dimensions of the roof and undergoes relatively little deformation under load.

They are commonly used where a building interior needs to be free from intermediate walls or columns that might support a more conventional flat or pitched roof, such as; libraries, theatres, leisure centres, airport and railway terminals, and so on.

Shell roofs can be ‘flat’, but are typically curved, assuming a cylindrical, domed, paraboloid or ellipsoid shape. The curvature of shell structures benefits from the same structural efficiency as arches, which are pure compression forms with no tensile stresses. Because of their structural efficiency less material is generally needed compared to more traditional roofs. However, a restraining structure such as an edge beams is required to prevent the shell from ‘spreading’.

Shell roofs may be:

• Single shells such as the dome of the Pantheon in Rome.
• Multi-shell roofs such as Eero Saarinen’s JFK International Airport in New York.
• Reinforced with structural ribs, such as Jørn Utzon’s Sydney Opera House.
• Lattice structures, such as Norman Foster’s Great Court at the British Museum in London.

They are most commonly constructed using insitu reinforced concrete, however, other materials such as and timber and steel may be used for reinforced, lattice or composite structures.

NB the term 'shell and core' refers to a developer's base build that is subsequently fitted out before the building is occupied. For more information see: Shell and core.

[edit] Related articles on Designing Buildings Wiki

• A-frame house.
• Arches.
• Barrel vault.
• Cantilever.
• Conoid shell.
• Domestic roofs.
• Folded plate construction.
• Hyperbolic paraboloid.
• Long span roof.
• Megastructure.
• Pendentive dome.
• Portal frame.
• Purlins.
• Shell and core.
• Sydney Opera House.
• Tensile structures.
• Tension.
• Tension cable and rod connectors.
• The history of fabric structures.
• Types of dome.
• Types of roof.
• Vault.

[edit] External references

• ‘Building Construction Handbook’ (6th ed.), CHUDLEY, R., GREENO, R., Butterworth-Heinemann (2007)