Wave-induced pressure distribution and force characteristics of box and rectangular girders under multiple wave conditions

Tsunami events impose significant challenges to the serviceability and structural safety of low-clearance cross-sea bridges. A physical model experiments with a total of 144 scenarios were conducted to investigate the spatiotemporal evolution of surface pressure and wave-induced forces on girder structures. To supplement experimental observations and provide additional insight into wave-structure interaction mechanisms, ANSYS Fluent 2022 R1 (Fluent) was employed for two-dimensional numerical simulations. The results reveal that pressure peak positions and spatial distribution patterns are predominantly governed by submergence level and cross-sectional geometry. Wave amplitude primarily controls the magnitude of pressure and wave forces; it has a limited influence on the spatial distribution patterns. The vertical wave force component substantially exceeds the horizontal component, with the disparity exceeding a factor of 20 under emerged states. Box girders exhibit more scattered pressure peaks and up to 59% higher maximum horizontal forces compared to rectangular girders, attributed to multi-surface interactions involving cantilevered flanges and recessed webs. This study contributes to an improved understanding of wave–structure interactions and provides essential insights for the hydrodynamic design and safety evaluation of coastal bridge superstructures.