Seismic modelling and analysis of masonry building in aggregate: A case study

The reuse of historical centers requires to solve in a reliable manner the problem of seismic analysis of the residential units belonging to building clusters. This implies complex interactions at the structural level, which influence the seismic response and damage mechanisms of the individual units. Even if a rigorous approach would require the analysis of the entire aggregate, in the professional practice, the safety assessment is typically performed on the single unit [1]. At the regional scale, empirical methodologies aimed at taking into account the variation of the vulnerability according to the position of the unit within the aggregate and some geometrical features were developed. In the case studies here presented, a computational modelling in the non-linear dynamic field is performed, which allows to calibrate the fragility curves for the building aggregate. The case studies are two large building clusters located in Puglia (in the historical centers of Foggia and Sant'Agata di Puglia [2]). Preliminary FEM simulations under seismic actions provided information about the overall response in terms of vibration and deformation modes, allowing to select the most significant ones. Then, it was possible to define a simplified plane model, able to represent the transversal response, which revealed to be the predominant one. Moreover, some partial, simplified models were defined for limited architectural parts that are particularly representative regarding the development of mechanisms of damage and collapse [2]. These models, consisting of an assembly of quadrilateral elements, are formulated in accordance with a RBSM approach [3,4]. Non-linear dynamic analyses have shown that the vulnerability is very different from the one predicted by classical vulnerability methods, highlighting that in the case of complex cluster, a more detailed and specific tool for the vulnerability analysis is required.