Analysis of hydrodynamic forces acting on submerged decks of coastal bridges under oblique wave action based on potential flow theory

The structures of existing coastal bridges without appropriate clearance between the still water level and low chord of the bridge deck, are vulnerable to wave-induced damage due to the strong wave force acting on the bridge deck during a hurricane or typhoon. This paper presents an analytical solution for hydrodynamic wave forces acting on girder-type bridge decks under hurricane-generated oblique water waves based on linear potential theory. First, some necessary assumptions are made, and the boundary value problem is defined. Then, the mathematical formulation and analytical solution of this wave-structure interaction problem are derived using the method of separation of variables. After determining the unknown coefficients of the velocity potentials with the matching eigenfunction expansion method, the wave forces acting on a submerged deck are obtained from the velocity field by applying the Bernoulli theorem. Finally, the analytical solution of the wave force is validated by the data from two different scaled hydrodynamic experiments. Employing the proposed method, the wave forces acting on a bridge deck are investigated considering the effect of the wave propagation direction, wave properties, and structural configuration. The parametrical analysis shows the potential for minimizing the horizontal wave force by the optimization of the structural configuration.