REFINED MODELLING AND ANALYSIS OF BUILDING AGGREGATES FOR THE ASSESSMENT OF SEISMIC RESPONSE

Unreinforced masonry (URM) buildings constitute a large portion of Italian-built heritage. URM derive from the process of expansion, completion and transformation of the structural units, especially in the historical city centers. Masonry aggregates can be arranged in a large number of possible configurations, which can include different interstorey heights, different number of stories, different planar shapes and different masonry typologies. However, the major uncertainty is related to the degree of connection between the structural units, which significantly conditions the response. Because of these reasons, the assessment of URM aggregate is not simple and deserves in-depth investigation. In this paper, a reference building aggregate is modelled and analyzed under different arrangement conditions. The numerical model makes use of homogenized masonry approach by means of 2D shell-layered elements, which can account both for the inplane and out-of-plane response. The model is realized with the STKO software platform for OpenSees. Different boundary conditions are analyzed, namely the deformability of floors, and the composition of the aggregate. Nonlinear static and dynamic analyses are carried out for the different case-studies highlighting the influence of the aforementioned conditions on the response of the structural units and on the extent of the so-called “aggregate effect”.