Finite element frequency analysis of bridge pier under the soil-pile interaction

Offshore bridges always play an important role under multi-hazard circumstances. In 1989, San Francisco earthquake significantly damaged the San Francisco-Oakland Bay Bridge and caused serious disaster. It also caused many other bridges serious damages that affected the rescue. Hence, it is important to evaluate the performance of bridge under an earthquake. In addition, it is necessary to consider the soil and structure interaction when we design a bridge subjected to dynamic loading. The dynamic behavior of bridge structure is one of the important factors in seismic design. The most important of the dynamic characteristics of the bridge is its fundamental frequency and fundamental vibration mode. In this study, we use the ABAQUS finite element program to analyze the performance of bridge pier under soil and structure interaction. The finite element models of soil adopting the soil spring built upon the empirical equations proposed by API are used to calculate the nature frequencies of bridge pier first. Then, the numerical results are compared with the nature frequencies obtained by the experimental data of shaking table test. In addition, a dynamic load is applied to the infinite element model of bridge pier to observe whether the displacement response has a resonance phenomenon, and to make sure that the natural frequency obtained by ABAQUS solver is accuracy and rationality. Finally, parameter analyses are performed to study the influence of pile exposed on the fundamental frequency of the bridge pier.