Simplified indexes for the seismic vulnerability of ancient masonry buildings

This paper presents a contribution for the safety assessment of historical masonry buildings under seismic loading. Three different simplified safety indexes (in-plan area ratio, area to weight ratio and base shear ratio) are analyzed, taking into account a large sample of 58 Portuguese churches. The sample of buildings has been organized according to the seismic zonation, from high to low seismicity. The results indicate that valuable information can be obtained from simplified methods, with respect to performing a first screening and to prioritizing further, deeper investigations. A new proposal is made regarding the combined usage of two of the indexes.