Italian National Seismic Prevention Plan: cost analyses for risk reduction policies

Abstract

The Italian National Seismic Prevention Plan (NSPP), born following the 2009 Abruzzi earthquake, gave light to an ambitious process aimed at the seismic upgrading of strategic and critical structures overall the Country. The coordination of the Plan is in charge of the Italian Civil Protection Department (ICPD), while Regions are appointed for its execution at a local level. To date, 1,207 structural interventions on buildings have been funded by NSPP, 510 of which so far concluded.The paper describes the state of the art of the Plan, relevant to public buildings, presenting some statistical analyses, compared with those developed in 2021, in terms of general features of the samples, safety indicators and costs sustained, to support the general strategy of seismic risk prevention and define future perspectives. Thanks to the enlargement of the statistical sample (passed from 1.034 to 1.207 items), more robust regression analyses and reliable equations are herein obtained and discussed. The updated sample relevant to buildings is formerly introduced in terms of typological characteristics, intervention types, relevant costs, and associated risk indices (before and after structural interventions). Then, a focus is set on sub-samples with concluded works, related to reinforced concrete buildings, masonry, and mixed structures. Analyses in terms of increment of the seismic safety index and marginal costs defined by unitary costs per percentage point increase of safety index, for the three different structural types are compared with those obtained by the authors in 2021. Finally, some conclusions are drawn from the formulations found and marginal costs obtained. These relationships, calibrated on the upgraded dataset, can be used to support the decision-making in deciding among different risk mitigation strategies, depending on the budget available and on the desired level of safety to be attained, according to a methodology previously developed by the authors.