A methodology for selecting optimal seismic risk mitigation strategies for the Italian residential masonry built heritage

Italy is one of the most seismically active countries in Europe, with a long history of destructive earthquakes that have caused significant human and economic losses. The country's extensive stock of unreinforced masonry buildings, many of which are residential and of historical value, is particularly vulnerable to seismic events. In recent decades, the Italian government has faced major costs associated with earthquake damage, highlighting the urgent need for the definition of comprehensive seismic risk mitigation strategies. This study presents an integrated approach to identify optimal seismic risk mitigation strategies for the residential masonry building stock in Italy. By developing and applying fragility models for both as-built and retrofitted buildings, the research assesses the effectiveness of possible strengthening techniques. The study also incorporates a cost model for the selected interventions, enabling cost-benefit analyses to assess their feasibility at a territorial scale, based on the expected direct economic losses from structural damage. The payback time of the initial investment for the intervention is computed, and by combining the cost-effectiveness of the intervention with the increase of building performance, different strategies to select the best interventions at municipal level have been elaborated. This work thus provides policymakers with a methodology to prioritize seismic retrofitting at a territorial scale, to boost the execution of interventions and enhance the overall seismic resilience of the Italian building stock.