Derivation of seismic fragility curves through mechanical-analytical approaches: the case study of the URM school buildings in Friuli-Venezia Giulia region (Italy)

Seismic events worldwide have shown that school buildings can exhibit vulnerability levels even higher than ordinary buildings. This highlights the urgent need for reliable risk analyses to guide decision-making in the implementation of large-scale mitigation policies. Developing seismic fragility curves that accurately reflect their typological and structural features is essential to achieve this. In this context, the paper compares two different mechanical-analytical methods, namely the “DBV-Masonry” and “Firstep-M_PRO”, which have been independently developed at the University of Genoa and at the University of Trieste, respectively. Among various possible methods, the mechanical-analytical approach is chosen for its computational efficiency in assessing large portfolios and its flexibility in capturing the features of specific buildings, such as schools (i.e. significant inter-story height and spacing between internal transversal walls). Both methods are applied to the same sample consisting of 101 unreinforced masonry (URM) schools located in the Friuli-Venezia Giulia region (Italy). One of key-goals of the paper is to provide a very comprehensive comparison of the similarities and differences between two methods for deriving seismic fragility curves which refer only to the global in-plane response. The impact of such an epistemic model uncertainty, together with the inter-building variability, is thus quantified and fragility curves are also validated against results from previous studies.