Dynamic Response Evaluation of Bridges Considering Aspect Ratio of Pier in Near-Fault and Far-Fault Ground Motions

Abstract

The recent increase in earthquake activities has highlighted the importance of predicting the seismic response of structures. Damage to civil infrastructure, particularly bridges, can cause considerable human and property losses. The seismic performance of a structure should be evaluated based on the characteristics of structures and earthquakes. For this, this study defined the two main factors of ground motion and structural system that affect the seismic response of a structure. Ground motions, which are mainly dependent on the distance from the epicenter, were defined as near-fault and far-fault ground motions. Near-fault ground motion includes the characteristics of forward directivity and fling step. In addition to ground motion, the aspect ratio of the pier, as a representative factor of a structural system, influences the seismic behavior of bridges. Thus, this study assessed the seismic response of bridges with various aspect ratios under the near-fault and far-fault ground motion conditions. Nonlinear static analysis was first performed to evaluate the seismic capacity of the pier. Then modal and dynamic analyses were carried out to examine the effects of the aspect ratio and ground motion on the displacement and force response and the change in the natural frequency of the bridge.