Compound-based approach for large scale seismic vulnerability assessment: application to the Garfagnana area in Tuscany

In this paper, a rapid procedure for vulnerability and risk analysis at urban scale is presented and validated with respect to a homogeneous territorial area. The methodology is aimed at defining fast evaluations by taking advantage of a division of the territory into compounds based on historical evolution and development of the urban clusters. A compound-based taxonomy realized according to the CARTIS methodology has been adopted as exposure model. The vulnerability models have been validated with respect of recent seismic events for both masonry and RC buildings. Hence, a modified macroseismic vulnerability model for compound evaluations has been used. The simplified procedure has been evaluated with respect to a unit-based analysis where every structural unit has been specifically investigated through a macroseismic approach. The comparisons between the compound-based (CB) and the building-by-building (BB) evaluation are obtained in terms of damage scenarios through binomial distributions. The procedure has been validated by assessing two distinct urban centers located in the Garfagnana area, Tuscany (Italy). The results show that the simplified procedure matches the forecasted damage states, limiting the required information and the time of the investigation. The evaluation has been finally extended to the territorial area of Garfagnana and part of the Lunigiana, analyzing a total of 17 municipalities where the CARTIS taxonomy is available. Herein, fragility curves have been derived according to unified classes for a territorial evaluation. The research proves the effectiveness of the procedure in evaluating the seismic vulnerability of large areas, presenting a rapid tool useful for administrators and stakeholders in the management of urban stock.