Time domain boundary element modeling of coupled interaction between ocean wave and elastic bridge pier

Abstract

High-rising bridge pylons or piers in coastal site are flexible enough to induce obvious interaction effect against ocean waves which could alter the dynamic properties and affect the resultant structural response. This study proposes a time domain boundary element approach to investigate the instantaneous coupled interaction between ocean wave and flexible structure with arbitrary geometry. The boundary element theory is integrated with Euler-Bernoulli element following a time integration scheme. The simple Green function associated with perturbation expansion is employed to build the time-invariant hydrodynamic matrix and Newmark method with additional numerical damping is used to integrate the structural response. The proposed approach is validated against both of a benchmark experiment and a previous frequency-domain approach. The interaction effects on structural dynamic properties as well as simultaneous structural response, wave run-up and surface pressure are characterized. The computational efficiency and stability are discussed. Results show that interaction effect might alter the fundamental period and damping ratio and affects the structural response considerably. The proposed approach shows both favorable accuracy and efficiency and could provide more transient information which is absent in previous frequency domain approaches.