Comparative analysis among different analysis programs for seismic vulnerability evaluation of a masonry building compound in the District of Naples

Masonry building compounds are sets of structural units having at least one common wall. The numerical analysis of the structural units grouped in aggregate, which are very diffused in Italian historical centres, is needed for identifying the structural interactions among them. Starting from these premises, in the current paper a masonry building aggregate built in the early twentieth century in the municipality of Cercola (district of Naples, Italy) and made of four structural units has been investigated as a case study. The structural behaviour under seismic forces has been investigated through non-linear static analyses. In particular, both the whole aggregate and the individual structural units have been modelled. Moreover, the single structural units have been considered both in the grouped and isolated conditions in order to assess either the beneficial or detrimental effect of the aggregated condition. The numerical models have been carried out with three different FEM software, namely 3MURI, CDS Win and Edilus, which schematise masonry buildings in different way. The analysis purpose has been to highlight the different results obtained with the three programs and to assess the most reliable seismic behaviour of investigated structural units. Finally, the susceptibility at damage of the case study aggregate has been evaluated through empirical fragility curves and mechanical vulnerability curves, which have been compared to each other and can be considered as preliminary tools to setup effective rehabilitation interventions.