Seismic vulnerability assessment of stone masonry façade walls: Calibration using fragility-based results and observed damage

This paper is focused on the calibration of a simplified seismic vulnerability index method for masonry façade walls, through an innovative two-step calibration process based on two complementary approaches. The first one is based on a set of fragility curves constructed from out-of-plane damage limit states obtained from experimental data, which are used to calibrate the weights associated to the parameters of the vulnerability index method that rule the out-of-plane response of the masonry façade walls. The second approach, subsequently used to calibrate the weights of the remaining vulnerability parameters, is based on post-earthquake damage data collected after the seismic event that struck the Azores Archipelago in July 1998. The results obtained from such calibration are then presented and critically discussed taking into account not only the calibration itself, but also their reliability from the methodological point of view. Finally, the addition of three new evaluation parameters is further proposed and analysed. This two-step calibration process represents a valuable contribution for the current state-of-art of the simplified seismic vulnerability assessment methodologies which, up to the present, have been developed and calibrated only on the basis of empirical data.