Numerical study on the force mechanism of the superstructure of offshore box bridge under tsunami actions

This paper presents a beam-pier structure model based on the Reynolds Averaged Navier-Stokes (RANS) equation and offshore box bridges to investigate the effect of tsunami-induced forces on the superstructure of offshore box bridges. The validity of the numerical simulation is substantiated through the comparison with wave surface theoretical solutions and experimental results. Subsequently, the force mechanism acting on the superstructure of offshore box bridges under tsunami actions is analyzed using the proposed model. The research results show that the peak value of horizontal and vertical forces can be divided into fluctuating growth stages and stable stages with different distances between the center of the section beam and the center of the pier. Notably, the vertical force peak is more susceptible to the pier compared to the horizontal force peak, while the overturning moment on the box girder by the pier has a significant influence. This study is of great significance in the realm of bridge failure modes identification and the formulation of measures aimed at disaster reduction and protection.