Study on the impact of the perforated floating breakwater on coastal bridge with box-girder superstructure under two-dimensional focused waves

The advantages of Floating Breakwater encompass its adaptability to varying water depths and tidal ranges, as well as its economic viability, mobility, and ease of installation. However, limited research has been conducted on the wave damping performance of floating breakwaters on the box-girder superstructure of coastal bridges during extreme wave conditions. In this study, a two-dimensional numerical model was established using the RANS equations and SST k-ω turbulence model in OpenFOAM. The breakwater was constrained by mooring forces, with linear elastic deformation, and underwent horizontal, vertical, and torsional movements under the action of ocean waves. The validity of the numerical model was confirmed by comparing it with existing numerical simulations and experimental data. The study examined influential factors, including the cross-sectional shape, submergence depth, and spacing of the floating breakwater, with a specific emphasis on the dimensions of the upper and lower openings for perforated breakwaters. Combined with attenuation rates and fluid-structure coupling analysis, the wave damping performance of the floating breakwater on the box-girder superstructure of coastal bridges under extreme wave conditions was evaluated. The research results demonstrate that the perforated floating breakwater, with Cs = 0.75, L = 10 m, and upper opening B1 = 0.1 B and lower opening B2 = 0.4 B, maximizes the wave damping performance on the box-girder superstructure of coastal bridges, which holds crucial significance for studying wave attenuation and disaster prevention on the box-girder superstructure of coastal bridges.