A NUMERICAL STRATEGY TO ASSESS THE STABILITY OF MASONRY VAULTS: A CASE STUDY IN THE URBINO PALACE

A simple and rapid method for predicting the stability of historical masonry vaults under gravity loads is presented, with an application to a notable case study in Italy, namely a vault belonging to the Ducal Palace of Urbino. The structure examined is a barrel vault with a significant span, located in the underground level of the Palace. Given the pressing need for a stability assessment to prevent collapse, geometric and material data are obtained through on-site surveys. To evaluate stability and assess collapse risk, a simple numerical approach is developed based on the utilization of the simplest Finite Element available in the most diffused commercial software, i.e. a truss exhibiting elastic-perfectly plastic or elastic-perfectly brittle behavior (also known as cutoff bar). The approach proposed is heterogeneous, hence the blocks are discretized using common isoparametric four node elastic elements in plane strain, whereas the mortar joints are modelled with orthotropic shell elements coupled with elastic perfectly brittle cutoff bars, in which all the nonlinearity is lumped. The results are compared with those obtained using a widely benchmarked 2D in-house computerized limit analysis software. Simultaneously, the same code is applied to the 3D case that includes seismic actions. After a comprehensive analysis of the results a safety assessment of the barrel vault is provided.