Fragility curves of masonry buildings in aggregate accounting for local mechanisms and site effects

Abstract The seismic evaluation of masonry buildings in aggregate, largely diffused within the existing Italian and European building stock, represents a difficult open task that has not been exhaustively investigated so far. study proposes procedure aimed at evaluating potential impact combination local mechanisms site-amplification terms fragility curves on an unreinforced (URM) aggregate which is made five adjacent structural units mutually interacting with each other during sequences. case inspired by built heritage historic centre Visso struck Central Italy 2016/2017 earthquakes. in-plane (IP) response URM was simulated through nonlinear dynamic analyses performed 3D equivalent frame model structure, whereas out-of-plane (OOP) were analysed adopting rigid-block assumption but assuming, as input, floor accelerations derived from post-processing data global model. An innovative considering pounding effect to also presented. Two soil conditions assumed (freefield) without (bedrock) site amplification. results showed effects strongly affected vulnerability altering between IP OOP mechanisms. In fact, for bedrock condition, especially medium–high damage levels, prevailing respect response. Conversely, freefield mainly governed overall behaviour all consistently field evidence.