Seismic vulnerability and retrofitting of a historical masonry building

The paper presents the assessment of the seismic vulnerability of a historical masonry building located in Milan. After the identification of the mechanical properties by means of in-situ tests and Italian Technical Code indications, a finite element plate model has been implemented to analyse the dynamic behaviour of the building through a modal analysis. The masonry has been considered as a homogeneous material. The intermediate floors, realized with steel beams, did not match the requirements to be considered as rigid diaphragms. Therefore, they have been modelled as plates with appropriate thickness and stiffness. Even if the analysis results showed a good behaviour in terms of vibrational modes and participating masses, the introduction of new floors has been considered to guarantee a proper distribution of loads and improve the box behaviour of the structure. A modal analysis of the retrofitted configuration has been performed and the results compared with the ones of the initial configuration. The retrofitted configuration has been also studied using the equivalent frame approach. A nonlinear static analysis has been performed to evaluate the capacity of the structure and estimate the seismic risk index.