Seismic Response Analysis of Continuous Girder Bridges Crossing Faults with Assembled Rocking-Self-Centering Piers

Under the action of cross-fault ground motion, bridge piers can experience significant residual displacements, which can irreversibly impact the integrity and reliability of the bridge structure. Traditional seismic mitigation measures struggle to effectively prevent multi-span chain collapses caused by the tilting of bridge piers. Therefore, it is of practical engineering significance to explore the effectiveness of rocking self-centering (RSC) piers as seismic mitigation measures for such bridges. In this paper, cross-fault ground motion with sliding effects is artificially synthesized based on the characteristics of the fault seismogenic mechanism. A finite element model of a cross-fault bridge is established using the OpenSees platform. The applicability of RSC piers to cross-fault bridges is explored. The results show that RSC piers can significantly reduce residual displacement during cross-fault ground motions, facilitating rapid recovery after an earthquake. RSC piers significantly reduce residual displacement in cross-fault bridges, with the most notable vibration reduction effects observed in piers adjacent to the fault. When an 80 cm fault displacement occurs, the vibration reduction rate reaches 48%. Additionally, when the fault’s permanent displacement increases the risk of pier toppling, the vibration reduction effect of the RSC pier is positively correlated with the degree of fault displacement. However, the amplification effect of RSC piers on the maximum relative displacement of bearings in cross-fault bridges cannot be ignored. In this study, for the first time, RSC piers were assembled on bridges spanning faults to investigate their seismic damping effect. When the degree of fault misalignment is greater than 60cm, the seismic damping effect of RSC abutments is positively correlated with the degree of fault misalignment, and its amplifying effect on the maximum relative displacement of the bearing becomes more and more obvious with the increase of permanent displacement. For example, when the fault misalignment degree is 60cm, the vibration reduction rate is 39%, and when the fault misalignment degree is 90cm, the vibration reduction rate is 54%. Designers should rationally configure RSC piers according to the specific bridge and site conditions to achieve optimal vibration reduction effects.