Looking at the collapse modes of circular and pointed masonry arches through the lens of Durand-Claye’s stability area method

This paper addresses the problem of characterizing the mechanical behaviour and collapse of symmetric circular and pointed masonry arches subject to their own weight. The influence on the arch’s collapse features of its shape and thickness, as well as the friction between the arch’s voussoirs, is analysed. The safety level of arches is then investigated by suitably reworking in semi-analytical form the graphical method of the stability area proposed by the renowned nineteenth century French scholar, Durand-Claye. According to Durand-Claye’s method, the arch is safe if along any given joint both the bending moment and shear force do not exceed the values determined by some given limit condition. The equilibrium conditions corresponding to all possible symmetric collapse modes are individuated. As was expected, pointed and circular arches exhibit different collapse behaviours, in terms of both collapse modes and safe domain. The limit values of arch thickness and friction coefficient are determined and the results obtained consistently compared with those published by Michon in 1857.