Elements of Barrel Vaults


The structure above is a single barrel vault with edge beams. The shell has been allowed to project beyond the edge of the stiffener in order to show the shape of the shell. Stiffeners are required at columns. They do not necessarily have to be complete diaphragms, as shown here, but may be arches with a horizontal tie.

In contrast to folded plates where the thickness is based on the design of a slab element, the thickness of the barrel shell is usually based on the minimum thickness required for covering the steel for fireproofing, plus the space required for three layers of bars, plus some space for tolerance. If these bars are all half inch rounds, a practical minimum would be 3 1/4 inches. Near the supports the thickness may be greater for containing the larger longitudinal bars.

If more than one barrel is placed side by side, the structure is a multiple barrel structure and if more than one span, it is called a multiple span structure. Any number of continuous barrels or continuous spans are possible except that eventually provision should be made for expansion joints in a large structure.