Damage assessment and collapse investigation of three historical masonry palaces under seismic actions

The preservation (in terms of inhibition of failures and collapses) of architectural heritage against horizontal loads (such as earthquakes) requires an accurate assessment of the non-linear response up to failure: to this aim, the use of advanced numerical tools to perform three-dimensional non-linear dynamic analyses is fundamental. This paper investigates the performance (up to the activation of local failures and under horizontal loads) of three historical masonry palaces of the outstanding cultural heritage in Mantua (Northern Italy) after the 2012 Emilia earthquake. Despite the unquestionable importance of the three case studies, until now these palaces have not been studied with advanced numerical simulations; moreover, the recent seismic sequence and the consequent significant cracks patterns observed in the post-earthquake survey phase have pointed out their vulnerability even to small seismic actions. The first part of the study was addressed to an accurate knowledge of the three palaces, focusing especially on the information gathered during on-site surveys, bibliographical and historical research: the data collected were employed to detect the complex three-dimensional geometry of the palaces under study and to define the cracks patterns. In the second part of the study, detailed and representative three-dimensional finite element (FE) models of the structures were developed and non-linear dynamic analyses were carried out to obtain a deep numerical insight into the seismic response of the three palaces, identifying the most vulnerable elements for each structure. The comparison between the numerical results and the damage survey showed that the numerical approach used in this study may be an adequate tool to properly evaluate the seismic response of historical masonry buildings. A comparative assessment of the results obtained for the different palaces was performed in terms of predicted damage distributions, energy density dissipated by tensile damage and maximum displacements registered for the different macro-elements.