Seismic fragility curves for infilled RC building classes considering multiple sources of uncertainty

This paper presents damage fragility curves derived through an analytical approach for reinforced concrete building classes representative of the existing Italian building stock. Fragility curves are generated by adopting a fully probabilistic framework that relies on a cloud-based approach employing real ground motion records and allows accounting and propagating the main sources of uncertainty. The seismic performance of masonry-infilled reinforced concrete frames is estimated via nonlinear time-history analyses performed via a simplified multi-degree-of-freedom model named STICK, in which the behavior of the frame is concentrated at the storey level. Thanks to the versatility of the adopted analytical model and its reduced computational burden, the effect of the main uncertainties that are typically neglected or only partially considered during the generation of analytical fragility curves is accounted for within the framework. Specifically, the inter-building, intra-building, and record-to-record variabilities, as well as variability related to the definition of the building damage level are explicitly considered. Fragility curves are developed for Damage States compatible with the EMS98 scale as a function of the peak ground acceleration for building classes defined adopting as main attributes the number of storeys, the age of construction, the design level, and the typology of infill panels. The proposed fragility curves are also compared with existing empirical ones showing a good agreement that confirms the validity of the proposed framework.