Simplified procedures for seismic vulnerability assessment of masonry churches

The conservation of the huge building heritage in Italy is a very complex challenge considering the high structural vulnerability that characterizes historical buildings and the significant seismic hazard affecting the Italian territory. In order to adopt preventive policies aimed at preserving such a valuable heritage, in the last decades many simplified models calibrated on the evidences of the aftermath of strong seismic events and suitable for the damage prediction of homogenous class of buildings (e.g. residential buildings, schools, churches, etc.) have been proposed. The present study focuses on masonry churches, which revealed an exceptional seismic vulnerability after the meaningful seismic events that occurred in the Italian peninsula in the last decades. In particular, after the swarm event occurred in Central Italy in 2016, about four thousand masonry churches resulted damaged, they being collapsed or declared unsafe in the post-earthquake inspections. In the paper a state of art of predictive models for masonry churches present in literature is given. Then, a simplified empirical method for seismic vulnerability assessment of masonry churches is presented. The research is framed within a national project promoted by the agreement between the Italian consortium ReLUIS and the Department of Civil Protection (DPC), aimed at implementing national seismic risk maps for different structure typologies (i.e. residential buildings, schools, churches and bridges). The proposed empirical method, which considers only qualitative parameters available at a national scale, has been calibrated on the basis of the damage scenario observed in the aftermath of the L’Aquila (2009) and Central Italy (2016-17) earthquakes. The comparison with the results of the 1st Level methodology provided by the Italian code revealed a good correspondence in terms of vulnerability classes, showing the possibility that such a simplified method could be profitably used to implement national seismic risk maps for masonry churches.