Seismic fragility curves for traditional unreinforced masonry buildings of Barcelona, Spain

Abstract

Residential buildings in Barcelona are mainly reinforced concrete buildings and unreinforced masonry buildings with particular features, typical of the customary constructive techniques of the city. The unreinforced masonry buildings of Barcelona have an average age of more than 60 years and were built without any consideration of the seismic hazard. The building used here as a typical example has six stories, 18.9 m by 24.5 m in floor and 24 m in height. For representing this typology, a six-story URM building with 18.9 m by 24.5 m in floor and 24 m in height has been selected.
To analyze the dynamic behaviour of the building we used TreMuri computer program (Galasco et al., 2002), which is an excellent tool to describe the nonlinear in-plane mechanical behaviour of masonry panels and to assess the expected damage on masonry buildings due to earthquakes. The macro element model consists of panels, simulating piers and architraves, connected by means of rigid
blocks. The macro element takes into account both the overturning mechanisms, related to cracking at the corners, and shear mechanisms by means of a damage model with friction. In this way a generic wall with openings can be described by means of a limited number of unknowns, involving few model parameters.
By using the TreMuri program, a push–over analysis was carried out by using a lateral loading pattern corresponding to the third mode of vibration of the structures. In this way, we obtained the capacity curve for the building and then, by using also the demand spectra the performance point of the structure was obtained. Considering a lognormal probability distribution, we finally obtained seismic
fragility curves for the building. These curves will be used in developing seismic damage scenarios for Barcelona.