SEISMIC VULNERABILITY ANALYSIS OF HISTORICAL BUILDING AGGREGATES USING THE LOGIC TREE APPROACH

The seismic vulnerability assessment of historic centers often involves large portions of buildings arranged in aggregates, which characterize the original configuration of these areas. Fragility curves, expressing the probability of exceeding specific damage states due to seismic events, are among the most commonly used tools for large-scale seismic vulnerability assessments. However, the development of these curves is influenced by both aleatory and epistemic uncertainties. This study addresses these uncertainties by integrating a logic tree approach into the derivation of typological fragility curves for unreinforced masonry buildings susceptible to out-of-plane overturning mechanisms. The methodology is applied to the historic center of Sora, a town in Central Italy. Fragility curves are derived under different assumptions regarding façade-to-wall connections within aggregates. The results highlight that seismic vulnerability is strongly influenced by the predominant failure mechanisms and the connection conditions between structural units.