Automated model updating of a masonry historical church based on operational modal analysis: the case study of San Giovanni in Macerata

Over the past few decades, the conservation and seismic assessment of historical buildings has gained great importance. In particular, the prediction of the dynamic response of masonry constructions plays a central role in retrofitting and conservation interventions. Finite element modelling has become the most common and accessible approach to study the behavior of complex masonry structures, however, the gap between numerical and experimental analysis may lead to erroneous results. This work describes the model updating procedure applied to the finite element model of San Giovanni’s church in Macerata, condemned in October 2016 after the Central Italy Earthquake. The laboratory of Proof and Research on Structures and Materials of Roma Tre University carried out an extensive in-situ testing campaign including geometric survey, video endoscopy, flat-jack test, sonic tomography and ambient vibrations test in order to investigate the state of the building. The work involved both numerical and experimental analysis: the results of the testing campaign were interpreted and correlated with an accurate finite element model developed with the software Midas Gen. Operational modal analysis was performed in order to extract the modal parameters of the building (modal frequencies, shape vectors and modal damping). Material characteristics and boundary conditions were updated according to the Douglas-Reid method. In the end, the final model was compared to the initial model to evaluate and discuss the process.