shell structure

Used to form the roof and sometimes the enclosure of a building. Shell structures provide the structural support within themselves, without additional structural members, except as peripheral or edge beams or supports. There are numerous possible designs, but three basic forms can be distinguished:

1. a) single curvature shell structures, such as cylindrical shells (barrel vaults);
2. b) double curvature shell structures in the same direction, such as spherical domes or elliptical paraboloids; and
3. c) double curvature shell structures in opposite directions, such as saddles, conoids, hyperbolic paraboloids, and hyperboloids of revolution.

Shells structures provide long spans and, where repeated, form economical structural roofs, such as in industrial buildings. The more unusual shapes are used mainly for aesthetic reasons, such as in cultural or exhibition buildings.