Enhanced Strategies for Seismic Resilient Posttensioned Reinforced Concrete Bridge Piers: Experimental Tests and Numerical Simulations

Abstract

Recent studies have proposed and investigated the use of unbonded posttensioned (PT) bars in bridge substructure systems to improve their self-centering behavior. However, the lateral loading resistance and self-centering capacities of reinforced concrete (RC) piers with PT bars (i.e., the posttensioned RC bridge piers: PRC piers) could be easily compromised by early crushing of the base compression toe during a seismic event. Hence, in order to enhance the pier base integrity, the present study proposes and experimentally investigates three simple strategies for enhancing the seismic-damage resistance of PRC piers based on the use of (1) a steel tube to encase the PRC pier’s end segment; (2) ultrahigh performance concrete at the PRC pier’s end segment; and (3) engineered cementitious composite mortar bed underneath the pier bottom. The performance of these three PRC piers was assessed by comparing them with a conventional PRC pier under cyclic loading and considering the damage evolution and the cyclic force-displacement response. The comparison shows that the proposed enhanced PRC solutions allow improving the seismic performance of the system sustaining large lateral drifts with good self-centering behavior. Moreover, based on the test results, finite element models accounting for PT force loss and the rocking characteristics were validated to reproduce the piers’ cyclic response, thus highlighting the importance of considering PT force loss during numerical simulations.