Study of the seismic vulnerability of complex masonry buildings

The study of the seismic vulnerability of complex buildings belonging to an historical centre located in the Umbria region in Italy is presented here. An earthquake struck the area in 1997, which emphasized the high vulnerability of the masonry buildings, even in consolidated conditions. Since then a systematic study was carried out in collaboration among universities and public bodies, in order to set up proper methodologies for survey and damage classifications, structural analysis modelling and improvement intervention proposals. The necessity of organizing the study on building typologies (isolated, rows and complex aggregates) was evidenced. This allowed us to select suitable procedures for the seismic vulnerability assessments and to prove the reliability of simplified macro-element kinematics models to describe the behaviour of existing masonry buildings in limit conditions. Those models are particularly indicated for complex aggregates, where the high level of irregularities and structural deficiencies can make inapplicable standard procedures (e.g. based on the "box" behaviour), and are used both for vulnerability prediction analyses and for simulation of possible retrofitting interventions.