Study of wave impact forces on coastal bridge superstructure located on a sloping seabed

The extreme waves caused by typhoons (or hurricanes) pose significant safety threats to coastal bridges. Massive waves from Hurricane Ivan (2004) and Katrina (2005) destroyed several bridges along the coast of Gulf of Mexico. To address this engineering disaster issue, existing studies have investigated the wave impact on bridge superstructures located over a flat seabed, utilizing hydrodynamic experiments in wave flumes or computational fluid dynamics (CFD) simulations. However, there is limited research regarding the modulation effects of seabed topography on wave forces. In this study, a numerical model of wave impact on bridge superstructure located over sloping seabed was setup based on OpenFOAM software. The effects of factors such as coastal slope, incident wave characteristics, and bridge configuration on wave forces were systematically investigated. First, the accuracy of the present numerical model in simulating the incident wave surface and wave forces was verified using published experimental data. It was validated that the present numerical model can simulate the physical process of wave-bridge deck interaction with sufficient reliability. Subsequently, the study analyzed the differences in wave forces on bridge superstructures located on flat versus sloping seabed. The numerical results indicate that the sloping seabed significantly influences the wave forces acting on bridge superstructures, which is directly related to the distance from the bridge to the coast. The amplification of wave forces on bridge superstructure is related to the characteristics of incident waves, and is rarely affected by submergence of superstructure. The findings suggest that, in the design of nearshore bridges to resist wave forces, the influence of sloping coastal topography on wave loads must be carefully considered.