Seismic fragility assessment for a class of RC school buildings in Italy leveraging detailed and reduced-order models

A study is presented on the seismic fragility analysis of a class of existing RC school buildings in Puglia, Southern Italy. Firstly, we defined a taxonomy for identifying a homogenous building class, through the collection of typological data, such as construction age, number of storeys and construction materials. After, by means of the available Census data on Italian school buildings, we selected 735 units in the focused area to assembly a proper database to involve in the phase of numerical modelling and analysis. To assess fragility, we employed two modelling options: (a) a single-degree-of-freedom approach, by evaluating the backbone of the simplified models; (b) a multidegree-of-freedom approach, by means of some index buildings of the class for which a full knowledge of geometrical and mechanical properties is available, as well as their spatial nonlinear numerical models. Nonlinear time history analyses were performed on all simplified models to define specific class fragility, accounting for any source of variability (record-to-record and building-to-building). The results of the investigation are compared in terms of class fragility curves, in order to highlight the differences between the two modelling approaches.