The characteristic values of climatic actions in current structural design codes are based on a specified probability of exceedance during the design working life of a structure. These values are traditionally determined from the past observation data under a stationary climate assumption. However, this assumption becomes invalid in the context of climate change, where the frequency and intensity of climatic extremes varies with respect to time. This paper presents a methodology to calculate the non-stationary characteristic values using state of the art climate model projections. The non-stationary characteristic values are calculated in compliance with the requirements of structural design codes by forming quasi-stationary windows of the entire bias-corrected climate model data. Three approaches for the calculation of non-stationary characteristic values considering the design working life of a structure are compared and their consequences on exceedance probability are discussed.

The seismic performance assessment of heritage architecture presents many challenges due to the restrictions set forth by the conservation principles to protect the associated social and cultural values. These buildings are typically characterized by unreinforced masonry walls connected by tie-rods, vaults, and wooden floors. The era of construction dates to the time when seismic design regulations were largely unknown, making heritage structures potentially vulnerable to earthquake damage. This study presents the seismic performance assessment of the Jesuit College located in the southern part of the Old City of Dubrovnik. A series of field surveys were conducted to qualitatively examine the material composition and obtain geometrical details in part of the Croatian Science Foundation research project IP-2020-02-3531 entitled “Seismic Risk Assessment of Cultural Heritage in Croatia—SeisRICHerCRO”. The structural response is thoroughly investigated by means of a complex finite element model calibrated using the frequencies determined from ambient vibration measurements and material characteristics obtained from the literature review of representative cultural heritage buildings. The seismic performance is evaluated using linear static and response spectrum analysis in accordance with Eurocode 8 guidelines for the demand seismic action level. The numerical analysis indicates several structural components in the building exhibiting high shear stress concentration and exceeding the elastic tensile limit under the demand ground acceleration level. The assessment further reveals substantial out-of-plane bending of vulnerable wall components (identified by local mode shapes) at low peak ground acceleration levels. The stress concentration in numerous structural components leads to the identification of vulnerable zones where retrofitting measures are essentially required.

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.