Earthquake Performance of a Cultural Heritage Building: The Jesuit College in Dubrovnik, Croatia

Abstract

Cultural heritage buildings generally refer to the ancient structures having high cultural and historical significance. These buildings are constructed using obsolete practices and require special considerations with respect to the lateral resistance, especially in moderate and high seismic regions. This study focuses on the earthquake performance assessment of the Episcopal Seminary Building and Classical Gymnasium (Jesuit College) located in the Old City of Dubrovnik, Croatia (UNESCO World Heritage Site). The construction dates back to 1662 and was developed in different stages until 1765. During this period, Jesuit College suffered damages from two major earthquakes i.e., M7.6 Dubrovnik in 1667 and M6.9 Montenegro in 1979. The material composition, structural drawings, and fundamental frequencies of the building were previously obtained in the framework of the research project “Seismic Risk Assessment of Cultural Heritage in Croatia – SeisRICHerCRO”. The material is predominantly composed of irregular stone blocks laid in lime mortar. The structural details such as floor vaults, arches, flexible diaphragms, and spatially irregular openings are numerically modelled using the finite element method. The analytical model is calibrated by performing eigenvalue analysis to compute the material parameters i.e., elastic modulus and density (supported by extensive literature review) that allows the modal frequencies to match with the values obtained from the ambient vibration testing. The seismic performance is then evaluated using the linear analysis procedure in accordance with the current guidelines of the Eurocode 8 and the corresponding Croatian National Annex. For the design earthquake, critical damage zones are identified and recommendations for retrofitting measures are proposed.