Comparative seismic assessment of a medioeval masonry church in Southern Italy

A comprehensive numerical investigation on a medieval masonry church in Calabria region (Southern Italy) is presented. The church has historical and architectural interest, being one of the first examples of Christian temples in the area. It exhibits a number of irregularities in plan and elevation, plus a visible state of degradation of the masonry material that make the investigation of its vulnerability under horizontal loads advisable, also in light of an expected short term and strong seismic event in the area. The safety assessment under horizontal loads is done using a variety of numerical analyses, ranging from Response Spectrum Analyses RSAs, non-linear static (pushover) and limit analyses (both on pre-assigned failure mechanisms and with FEs). A refined full 3D plate and shell FE model is adopted, after detailed in situ inspection of the geometry and perusal of the historical documentation. Numerical results are obtained both by means of a noncommercial full 3D software developed by one of the authors (FE limit analysis), and a commercial code (Strand7®). Limit analyses with pre-assigned failure mechanisms, as per Italian guidelines for cultural heritage, are also performed, with evaluated collapse accelerations and associated mechanisms matching well with FE results. As a matter of fact, a remarkable consistency among all the different procedures is found, meaning that even simplified approaches (like limit analysis with pre-assigned failure mechanisms) or RSA (typically not recommended because of the linearity hypothesis for masonry) can provide -if critically analyzed - useful hints on possible damage patterns and active failure mechanisms in case of a seismic event. In all cases, numerical computations proved to be valuable tools to predict the most probable behavior in case of an expected strong earthquake, suggesting the most suited way for an effective strengthening.