Dynamic interaction between bridge pier and its large pile foundation considering earthquake and scour depths

Abstract

Scour can be a potential risk to bridge’s safety during the service life. Generally, the scour can increase the unsupported pile length of bridge and change the dynamic characteristics of the substructure. Consequently, this can decrease the lateral load capacity of the bridge, especially to pile-supported bridges. In this article, the dynamic interaction between bridge pier and its foundation considering earthquake and scour depths was investigated based on a simplified 2-degree-of-freedom model. The results demonstrated that there is a significant resonance between the pier and the pile foundation due to the contribution of large pile cap mass. Additionally, the effect of scour depths is strongly related to the fundamental vibration periods of both the superstructure–pier system and the pile foundation itself. Moreover, an approximate most adverse equivalent pile length considering the scour depth was formulated and proposed to efficiently and easily capture the worst seismic responses of the bridge pier. The accuracy of the methodology proposed herein was verified by an existing three-span continuous girder bridge in China.