Experimental and 3D numerical investigation of solitary wave forces on coastal bridges

In this paper, solitary wave-induced vertical and horizontal forces on coastal bridges are investigated by laboratory experiments as well as computational fluid dynamics (CFD) analysis. The effects of different parameters (e.g., water depths, submergence depths, wave heights) on wave-induced force on a 1:30 scale bridge model are studied. Specifically, the models of deck with and without girders are tested to explore the effects of girders and trapped air on structural response. It is demonstrated with the collected experimental data that girders can increase the wave loads acting on decks and the trapped air makes the structure more unstable. Additionally, a secondary impact may occur due to the bluff profile of girders. Subsequently, based on solitary wave theory and experimental data, a linear relationship is quantified between wave forces and wave steepness. Following the experiments, numerical analysis using both two-dimensional (2D) and three-dimensional (3D) models is conducted to assess vertical and horizontal forces. The comparisons between experimental study and numerical computation indicate that the 2D model can well assess most of the cases for deck without girders, but fails to simulate accurate results for deck with girders, indicating that 2D model cannot deal with complex interactions among wave, structure and trapped air. The 3D model can obtain more accurate wave forces, and better capture the detailed characteristics of solitary wave forces. With the information presented in this study, it can aid the design and management of coastal structures under hurricane and tsunami loads.