The seismic events that struck Italy in the last decades have highlighted the high seismic vulnerability of the built heritage, especially of historical masonry buildings. It is therefore of utmost importance to plan and prioritize mitigation strategies that can effectively reduce the amount of economic losses and the number of casualties produced by earthquakes. In order to do so, the vulnerability of buildings must be estimated accurately: firstly, the as-built vulnerability has to be assessed, and secondly it shall be compared with the one resulting from simulations of possible retrofit strategies.

This work focuses on the definition of vulnerability for Italian residential masonry buildings designed before 1919. Fragility curves are elaborated for a database of 205 buildings through Vulnus 4.0, a software that performs simplified mechanical analyses for load-bearing masonry buildings. These fragility curves are derived both for the as-built configuration and different intervention solutions, and are then processed to have fragility sets for the specific building typology analysed. These vulnerability models are then combined with hazard and exposure data within the IRMA platform (Italian Risk MAps) developed by Eucentre and DPC (Italian Department of Civil Protection). IRMA can elaborate seismic risk maps for Italy which show the possible losses for different return periods and time windows. By comparing the results provided by IRMA for the as-built configuration and the retrofit cases, it has been possible to quantify the effectiveness of different mitigation strategies in terms of vulnerability reduction, as well as their economic trade-off when considering the implementation costs.