A shell is a type of structural element which is characterized by its geometry, being a three-dimensional solid whose thickness is very small when compared with other dimensions, and in structural terms, by the stress resultants calculated in the middle plane displaying components which are both coplanar and normal to the surface. Essentially, a shell can be derived from a plate by two means: by initially forming the middle surface as a singly or doubly curved surface, and by applying loads which are coplanar to a plate's

plane Plane(s) most often refers to: * Aero- or airplane, a powered, fixed-wing aircraft * Plane (geometry), a flat, 2-dimensional surface Plane or planes may also refer to: Biology * Plane (tree) or ''Platanus'', wetland native plant * Planes (gen ...

which generate significant stresses. Thin-shell structures (also called plate and shell structures) are lightweight constructions using shell elements. These elements, typically curved, are assembled to make large structures. Typical applications include aircraft fuselages, boat hulls, and the roofs of large buildings.

Definition

A thin shell is defined as a shell with a thickness which is small compared to its other dimensions and in which deformations are not large compared to thickness. A primary difference between a shell structure and a plate structure is that, in the unstressed state, the shell structure has curvature as opposed to the plates structure which is flat. Membrane action in a shell is primarily caused by in-plane forces ( plane stress), but there may be secondary forces resulting from flexural deformations. Where a flat plate acts similar to a beam with bending and shear stresses, shells are analogous to a cable which resists loads through tensile stresses. The ideal thin shell must be capable of developing both tension and compression.

Types

The most popular types of thin-shell structures are: * Concrete shell structures, often cast as a

monolithic dome A monolithic dome (from Greek mono- and -lithic, meaning "one stone") is a thin-shell structure cast in a one-piece form. The form may be permanent or temporary and may or may not remain part of the finished structure. Monolithic domes are a f ...

stressed ribbon bridge A stressed ribbon bridge (also stress-ribbon bridge or catenary bridge) is a tension structure (similar in many ways to a simple suspension bridge). The suspension cables are embedded in the deck, which follows a catenary arc between supports. ...

saddle roof A saddle roof is a roof form which follows a convex curve about one axis and a concave curve about the other. The hyperbolic paraboloid form has been used for roofs at various times since it is easily constructed from straight sections of lumber, ...

* Lattice shell structures, also called gridshell structures, often in the form of a geodesic dome or a hyperboloid structure *

Membrane structure Membrane structures are spatial structures made out of tensioned membranes. The structural use of membranes can be divided into pneumatic structures, tensile membrane structures, and cable domes. In these three kinds of structure, membranes work ...

s, which include

fabric structure A fabric structure is a structure made of fabric, with or without a structural frame. The technology provides end users a variety of aesthetic free-form building designs. Custom-made structures are engineered and fabricated to meet worldwide struc ...

s and other tensile structures, cable domes, and pneumatic structures.

References

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Thin-shell structures

Double thin-shells structures

Hypar & Concrete Shells

Past and Future of Grid Shell Structures

Shape optimization of Shell and Spatial structure

Lattice Shell for Space Vehicles

International Association for Shell and Spatial Structures
Solid mechanics Structural system {{Civil-engineering-stub

Definition

Types

See also

References

Further reading

External links