In the prvious chapter, barrel vaults were described having a length of barrel which is long in comparison to the width. In this chapter, the structure known as the short shell will be described. This structure is a cylindrical shell having a large radius in comparison to the length. The two types of shells have uses which are altogether different and the architectural and engineering problems require a different approach. There are, of course, borderline cases where it is difficult to distinguish between the long an short shell.

In structures making use of the short shell, the principle structural element is the stiffener, usually a reinforced concrete arch, although steel arches or trusses have been used. The short shell serves only a minor role, therefore, the emphasis in this chapter then will be on the arch shape. Many structures built with short shells, such a large hangars and auditoriums, could have been built with little more dead load by using a ribbed slab or other lightweight concrete framing system rather than the shell. The architecture of short shells, therefor, must be based on the exploitation of the shape of the arch rather than on the shell itself.