Shallow Square Intersection Shell


This structure is a dome formed by using triangular pieces of a cylindrical shell arranged in the form of a square. The drawing, however, conveys more than the description.

The word "shallow" has been used to indicate that the angle between the components is rather small, especially if the rise of the shell is small. With four sides, however, the ribs formed by the intersection should provide an adequate structural member. It is the best type of dome to cover a square area and maintain a level parapet around the building. The structural action is essentially that of a short shell. Loads are carried by the cross ribs formed by the intersection and by the stiffening element created by the edge beam. The bottom of the shell requires tensile reinforcement as in a short shell.

This structure can be inverted and supported from a central column similar to the "umbrella shell" described in the chapter on warped surfaces.