The effect of existing damage on the seismic performance of a historical masonry structure: a site-specific assessment

This study comprehensively evaluates the structural integrity and seismic performance of a historic masonry mosque, exhibiting significant settlement cracks, through an integrated approach combining field measurements and advanced numerical analyses. The Operational Modal Analysis (OMA) conducted to determine the dynamic characteristics of the structure. Field measurements revealed that the environmental vibrations originating from a nearby tram line causes significant amplitude incrase in one of the main columns. The dynamic characteristics of the structure obtained from field experiments are used to calibrate the numerical model via the Particle Swarm Optimization Algorithm. The calibrated numerical model, taking into account the existing cracks in the structure using contact elements, was subjected to nonlinear analysis in the time domain under 11 site-specific ground motion records selected in accordance with the procedures of the Turkish Building Seismic Code. This analysis examined the seismic performance and damage mechanisms of the structure. The findings revealed that while existing settlement cracks contribute to seismic energy dissipation through frictional sliding and gap opening mechanisms, they may also serve as potential failure initiation points under strong ground motions. This study’s integrated approach, combining dual-purpose OMA application and explicit crack modeling with contact elements, constitutes a novel methodological framework for the realistic seismic assessment of historic masonry structures with pre-existing damage.