Dynamic bridge fragility: evaluating tsunami-induced vulnerabilities

Recent seismic events in the Pacific Ocean have underscored the immense destructive potential of tsunamis, highlighting the need for robust engineering strategies to protect critical infrastructure.Existing research on tsunami-induced fragility functions predominantly focuses on quasistatic pressure distributions over infrastructure components, which often oversimplify the complex and dynamic nature of tsunami wave forces.This study bridges this gap by conducting a time history analysis of box girder bridges under dynamic wave loadings to develop fragility functions more reflective of real-world conditions.Leveraging linear wave theory, wave particle acceleration time histories are derived from tsunami inundation depths, which are stochastically generated through Latin Hypercube Sampling to ensure comprehensive coverage of potential scenarios.These acceleration profiles serve as input for finite element analysis of box girder bridges, enabling the evaluation of column ductility demand as the engineering demand parameter (EDP).The finite element analysis accounts for both material and geometric nonlinearities to capture the complex response of bridge structures under transient dynamic loads.The results inform the development of probabilistic tsunami demand models (PTDMs) via regression, which correlate EDPs with wave intensity measures such as peak wave acceleration.Fragility functions are then derived for various damage levels, capturing the progressive failure mechanisms of bridge components and system under varying levels of dynamic wave loading.These functions provide critical insights into the likelihood of structural failure at different tsunami intensities, offering a more nuanced understanding of bridge vulnerabilities.This research establishes a dynamic-focused framework for assessing and predicting bridge failures in tsunami-prone regions.