Numerical insights on the structural assessment of typical historical masonry vaults of Cagliari

Collapse behavior of masonry vaults is investigated with the aim to evaluate the role of brick patterns in their mechanical behavior. Attention is focused on lowered sail vaults typically built during the nineteenth-century in the city of Cagliari, Italy. A series of rigorous laser scanner surveys has been performed on some of these vaults in order to obtain the effective geometry both at macro-level – i.e. the vault shape – and at micro-level – i.e. brick patterns. Analysis is performed through a NURBS-based upper bound limit analysis approach. The representation of a complex geometry through NURBS (Non-Uniform Rational B-Spline) sur- faces is particularly suited to treat curved geometries, such as vaults. A mesh of NURBS element is defined: each element is idealized as a rigid body with dissipation allowed only along interfaces. In order to find the minimum live load multiplier, a procedure of mesh adaptation by a genetic algorithm is applied.