Numerical analysis of the mechanical role of the ribs in groin vaults

The role of ribs in the mechanical behavior of masonry cross vaults has been the subject of intense debates since the 19th century. Literature on the subject diverges from considering the ribs as the main load-bearing units which carry the weight of the masonry web, to the opinion that the ribs are merely decorations. This research focused on the simplest type of cross vaults, i.e. groined vaults formed by the intersection of two semicircular cylindrical mid-surfaces. Instead of the widely used Limit State Analysis which is reliable only if specific conditions are satisfied, discrete element modelling (the commercial code 3DEC, based on an explicit time integration scheme), and a classical finite element code (ANSYS) was applied in the investigations. In the applied DEM code (3DEC) the elements (corresponding to the voussoirs) may slide along each other, and can be separated from their neighbors in any directions; and new contacts may be formed between them, in a computationally efficient automatized manner.