MULTI-HAZARD FRAGILITY ASSESSMENT OF BRIDGES IN THE MEDITERRANEAN COASTAL REGIONS

In recent years, growing awareness of the severe threat tsunamis posing to coastal communities has intensified research on their impact, particularly on critical infrastructure such as bridges. While numerous experimental and numerical studies have been conducted to investigate structural vulnerability, analytical assessments remain limited, revealing a significant gap in the literature. Moreover, it is increasingly recognized that coastal regions often experience multi-hazard scenarios, where a tsunami is typically preceded by an earthquake. This sequence heightens structural vulnerability, as seismic damage can substantially reduce the structural capacity to withstand subsequent tsunami forces. This study introduces a probabilistic multi-hazard fragility assessment framework aimed at evaluating the influence of earthquake-induced damage on the structural response of bridges subjected to sequential tsunami loading. The methodology focuses on bridges with randomly defined geometric and mechanical characteristics representative of those commonly found in Mediterranean coastal areas. Utilizing Monte Carlo simulations, the approach incorporates uncertainties related to tsunami loading, structural configurations, and material properties, enabling a comprehensive and realistic assessment of bridge vulnerability. Simulation results are used to derive analytical lognormal fragility functions, and a comparative analysis between the numerical data and the fitted distributions confirms the robustness and accuracy of the proposed method. The findings underscore the importance of considering seismic pre-damage in tsunami fragility assessments and demonstrate the potential of the methodology for future applications in multi-hazard risk evaluation.