Quasi-static and nonlinear time-history analyses of post-tensioned bridge rocking piers with internal ED bars

Abstract

Post-tensioned (PT) rocking piers have been recently emphasized for satisfactory self-centering capacity and accelerated bridge construction (ABC) technique in high seismic regions. In this paper, quasi-static cyclic and nonlinear time-history analyses (NLTHAs) are conducted on the PT rocking piers incorporating internal energy-dissipation (ED) bars, based on two modeling techniques. The influences of three parameters consisting of the transverse reinforcement ratio, the area of ED bars and the initial total axial load on the hysteretic behavior of PT rocking piers are studied. The emphases of the quasi-static analyses are on the concrete strain and the neutral axis depth which are seldom referred in the previous researches. Furthermore, NLTHAs are conducted on a set of PT rocking piers under two suits of near-fault and far-fault ground motions (NFGMs and FFGMs) to compare the seismic behaviors of PT rocking piers with different design parameters. The results reveal that the area of ED bars and the initial total axial load are the key parameters that affect the seismic performance of PT rocking piers. In addition, pulse-like NFGMs with a high ratio (>0.2 s) between the peak ground velocity (PGV) and the peak ground acceleration (PGA) result in larger structural seismic responses than FFGMs, except for the acceleration response. The maximum displacement response subjected to FFGMs is almost unaffected by the area ratio of ED bars.