Numerical Approach of Interaction between Wave and Flexible Bridge Pier with Arbitrary Cross Section Based on Boundary Element Method

A numerical approach based on potential theory and the boundary element method (BEM) to study the interaction between surface waves and a flexible bridge pier will be developed. The conventional hydrodynamic approach in naval architecture for floating rigid structures will be extended to consider the hydroelastic problem of a deformable bridge pier with arbitrary cross sections. The Euler-Bernoulli beam constitutive model will be incorporated into the hydrodynamic equations to fully couple the motions of fluid and structure and the deformable boundary condition of the pier surface will be expressed in a fashion of structural mode superposition. The numerical results are validated against analytical solutions and a flexible bridge pier with an elliptical section is used as a study case. Based on the proposed approach, the structural responses of base shear force, moment, and pier top displacement subjected to regular and stochastic waves will be investigated. The wave runup, as well as the distribution of wave field, will be characterized. The effect of selected modes and water depth on the responses will be carefully examined. The results show that the interaction effect has an overall influence on both the structural responses and wave fields. The interaction effect might remarkably increase the stochastic responses of base shear force, moment, and pier top displacement, as well as the wave runup, on the pier surface. The increasing water depth dramatically enhances the interaction effect. The proposed approach reaches good convergence by employing the first five structural modes. (C) 2020 American Society of Civil Engineers.