The role of reinforced concrete roofs in the seismic performance of masonry buildings

The 2016 Central Italy earthquake caused many collapses of existing masonry buildings that had previously been retrofitted with reinforced concrete roofs. The aim of this paper is to explore the role of these roofs in the seismic behaviour of masonry buildings. Simple analytical models are presented to illustrate two typical out-of-plane collapse mechanisms: wall overturning and vertical flexure. The models are based on linear kinematic analysis, which allows fast modelling and calculation of a coefficient that can be used to assess the safety level of a structure. Nonlinear kinematic analyses were also performed. Both methods were applied to two case studies taken from areas struck by the earthquake. Results show that linear analysis represents an effective tool for preliminary verifications that can allow one to understand whether retrofit interventions are needed.