Abstract: In order to study the fragility of the double-deck viaducts frame piers under seismic action, based on the destructive test under low cyclic reciprocating loading, a nonlinear finite element model was built on the OpenSees platform. A probabilistic seismic demand analysis was performed on the structural model by selecting 100 actual ground shaking records as input. Through the fragility analysis of the four kinds of defined damage limit states, the seismic fragility curves of frame piers were obtained. The effects of the column reinforcement ratio (ρ) and the stirrup reinforcement ratio (ρsv) on the seismic fragility of the frame piers were analyzed by varying the structural parameters. The research results show that the displacement ductility ratio of the double-deck viaducts frame piers for slight damage, moderate damage, severe damage, and complete destruction of the structure are 1.0, 2.0, 3.5 and 5.0 respectively, and the median spectral accelerations are 0.46g, 0.66g, 0.88g and 1.06g respectively. From the perspective of safety and economy, the reasonable reinforcement ratio and stirrup reinforcement ratio of the columns are 1.6%~2.2% and 1.0%~1.5% respectively.

Key words: bridge engineering; frame piers; seismic fragility; displacement ductility ratio; spectral acceleration

摘要： 为研究双层高架桥框架式桥墩在地震作用下的易损性，基于双层框架式桥墩在低周往复荷载作用下的破坏性试验，采用OpenSees开放平台建立了非线性有限元模型；选择100条实际地震动记录作为输入，对结构模型进行概率地震需求分析；通过对定义的4种损伤极限状态进行易损性分析，得出框架式桥墩地震易损性曲线；通过改变结构参数，分析了立柱配筋率(ρ)和配箍率(ρsv)对框架式桥墩地震易损性的影响。研究结果表明：双层框架式桥墩发生轻微损伤、中等损伤、严重损伤和完全破坏时的位移延性比分别为1.0、2.0、3.5、5.0；谱加速度中位值分别为0.46g、0.66g、0.88g、1.06g；从安全与经济角度出发，立柱合理的配筋率和配箍率范围分别为1.6%~2.2%、1.0%~1.5%。

关键词: 桥梁工程；框架式桥墩；地震易损性；位移延性比；谱加速度