Seismic Resilience Assessment of the Hybrid Bridge Pier Based on Fragility Analysis

At present, the seismic structure of recoverable functional bridges based on seismic resilience is one of the hotspots in bridge seismic engineering research. Therefore, a new type of hybrid piers is designed in this paper, which mainly relies on replaceable components to achieve repairable structural performance after earthquakes. At the same time, four-level seismic fortification objectives based on seismic resilience is proposed, and the follow-up stiffness phenomenon is found on this basis. The finite element software OPENSEES was used to perform IDA analysis on a hybrid pier and an ordinary reinforced concrete (RC) pier. The fragility curves and seismic resilience curves of two piers were compared, and the seismic resilience performance and the follow-up stiffness phenomenon of the hybrid pier were studied. The results show that under the action of different seismic waves, the top displacement angle of the pier of the hybrid pier is slightly larger than that of the ordinary RC pier, but the overall difference is not large. The fragility curve of the hybrid pier is slightly larger than that of the ordinary RC pier. However, with the damage to the hybrid pier, the follow-up stiffness phenomenon impacts the seismic performance, which reduces the seismic force acting on the structure and improves the seismic resilience of the structure. The post-earthquake recovery time of two piers under different damage states was determined. Combined with the fragility curves, the seismic resilience curves of two piers were presented. The resilient index of the hybrid pier was always maintained at 0.9–1, and the seismic resilience performance was excellent.