Cross and Cloister Vaults

Abstract

The aim of this section is the study of Statics of cross and cloister vaults: they are related together in various respects, since from the point of view of their geometric generation. A brief introduction gives information about the historical development of these vaults: there are magnificent examples already in the Roman architecture. Membrane stresses in cross and cloister vaults are firstly thoroughly studied. The existence of tensile stresses is a necessary condition for the membrane equilibrium and cracking is thus nearly inevitable. A study of sliced models of both the vaults is thus pursued. In the sliced model of the cross vault, firstly proposed by Heyman, webs transmit vertical and horizontal loads to diagonal ribs or to groins that, in turn, convey these loads to piers and flying buttresses. A dual model for the cloister vault, that cracks along the diagonals and transmits loads on the side walls, is firstly proposed. A detailed analysis of the cracks patterns is conducted for both the vaults at their minimum thrust states. The chapter ends with the study of statics of some important examples of these vaults, as, in particular, the large cross vaults of the Diocletian Baths in Rome.