Fragility Functions of Masonry Buildings

This chapter proposes a method for the vulnerability assessment of ordinary masonry buildings at territorial scale, to be used in the framework of a probabilistic seismic risk analysis. The classification of the built environment is based on the SYNER-G taxonomy and is dependent on the available data in the study area; it consists in the aggregation of buildings characterized by a homogeneous seismic behavior, which is known from empirical damage on similar structures, proper analytical models or expert judgment. The general definition of fragility functions is recalled, through the use of static non linear analysis for the evaluation of the capacity spectrum and the calculation of the maximum displacement by the demand spectrum. The selection of proper intensity measures for masonry buildings is treated, as well as the definition of damage and performance limit states. A detailed procedure for the propagation of uncertainties is proposed, which is able to single out each independent contribution. Then, some recommendations for deriving fragility functions with different approaches are given. In particular, it is shown how the macroseismic vulnerability method, derived from EMS98, can be used by expert elicitation or if empirical data are available. Moreover, the DBV-masonry (Displacement Based Vulnerability) method is proposed as a powerful tool for the derivation of fragility function by an analytical approach. Finally, fragility functions are derived for ten different classes of masonry buildings, defined by a list of tags from the taxonomy, in order to show the capabilities of the proposed methods and their cross-validation.