A simplified loss-based procedure for seismic risk mitigation at a territorial scale

Abstract

The socio-economic and political impact of recent earthquakes proved the urgent need to develop a comprehensive methodology for creating earthquake scenarios and conducting risk analysis focusing on European buildings. Referring to the structural typologies identified by the European Macroseismic Scale (EMS-98), an easy procedure to identify the expected annual loss and the target of retrofitting interventions for reducing the seismic risk is developed, with the goal of promoting an analysis at territorial level. The procedure, based on the Loss-Based Earthquake Engineering, can serve as a tool for policymakers in planning future mitigation policies and assessing the effectiveness of implemented measures. Initially, a framework to identify the fragility curves for all building typologies, as classified in EMS-98, is proposed. In the second step, the expected annual loss is estimated through a simplified formulation. Finally, a closed-form equation is developed to identify recommended retrofitting interventions to achieve a target risk class. To promote the use of the procedure and prove its accuracy, it has been applied to several typological structures, and results have been compared with those derived by literature approaches. The proposed method is confirmed to be easily applicable and more accurate in economically quantifying the seismic loss, considering the period of vibration of the structure and the soil category. The use of the procedure is recommended to practitioners for a preliminary evaluation of the costs and benefits of structural interventions in large-scale planning.