SEISMIC RESPONSE ANALYSIS OF THE ROCKING SELF-CENTERING BRIDGE PIERS UNDER THE NEAR-FAULT GROUND MOTIONS

To study the seismic response of the rocking self-centering (RSC) bridge piers under near-fault ground motions, a series of numerical analysis models for the piers were built based on the OpenSees. Also, the seismic analysis models for the reinforced concrete (RC) and unbonded prestressed reinforced concrete (PRC) piers were built for comparison with the behavior of the RSC piers. Incremental dynamic analysis (IDA) was conducted for all the piers under the near-fault ground motions. The peak drift ratio, the residual drift ratio and the maximum prestressing stress of all the piers were obtained and compared with each other, and the piers were designed with different heights (aspect ratio=2.0, 4.0 and 6.0), different types (RSC, RC and PRC piers). It is found that the peak drift ratio and the maximum prestressing stress of the RSC piers will be reduced with the increment of the mild reinforcement ratio. Compared with the RC piers, both the PRC and RSC piers have smaller residual drift ratio. The RSC piers, which have the similar mild reinforcement ratio as the longitudinal bar ratio of PRC piers, have almost the same peak drift, residual drift and the maximum prestressing stress compared with the PRC piers. Prestressing tendon failure damage would occur for both the RSC and PRC piers with an aspect ratio equal to or larger than 6.0. To avoid larger residual drift ratio of the RSC piers as a result of prestressing tendon failure, the mild reinforcement ratio of the RSC piers should not be less than 0.75%.