Seismic Vulnerability Analysis of Small and Medium Span Girder Bridges Considering the Sliding of Bearing and Shear Key Damage
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摘要: 从板式橡胶支座及混凝土挡块抗震设计角度,以一座典型的3跨预应力混凝土连续梁桥为例,结合概率地震需求分析及桥墩、支座等抗震关键构件极限破坏状态,建立不同支座及挡块分析模型的中小跨径梁桥地震易损性曲线,研究考虑支座滑移效应及挡块破坏的中小跨径梁桥的易损性特征。研究结果表明:不考虑橡胶支座的滑移效应及混凝土挡块破坏,桥墩地震破坏概率明显增大,且会低估支座破坏概率;桥梁系统易损性受支座破坏状态的影响显著,需设置合理的限位装置;在中小跨径梁桥地震易损性分析中,考虑支座的滑移效应及混凝土挡块的破坏十分必要。Abstract: From the perspective of seismic designs of plate type elastomeric pad bearings and concrete shear key,a typical three-span prestressed concrete continuous girder bridge was taken as a case study. Combined with the probabilistic seismic demand analysis and the limit failure states of critical members such as piers and bearings,this study developed the vulnerability curves of the bridges with different models of bearings and shear keys and studies the Vulnerability characteristics of the small and medium-span bridge considering the slip effect of the bearing and the shear key damage. The results show that the seismic damage probability of the pier is obviously increased without considering the slip effect of bearings and the shear key damage,and the probability of the bearing damage is underestimated; the system vulnerability is significantly affected by the damage of bearings,and a reasonable limit device is needed for the bearing; the sliding effect of bearings and shear key damages should be considered in the seismic vulnerability analysis of small and medium span girder bridges.
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表 1 梁桥不确定参数及其概率分布
Table 1. Uncertainty parameters and distribution types of girder bridges
参数 分布类型 均值 变异系数 钢筋屈服强度/MPa 对数正态分布 381.65 0.074 混凝土抗压强度/MPa 正态分布 28.03 0.172 滑动支座摩擦系数 正态分布 0.06 0.5 支座剪切模量/MPa 正态分布 1.18 0.14 阻尼比 正态分布 0.05 0.2 上部结构质量/(kg·m3) 正态分布 2600 0.1 表 2 构件极限破坏状态及其限值
Table 2. Damage states and limit values of components
破坏状态 桥墩曲率延性比$\mu {}_\varphi $ 支座水平位移u/mm 轻微破坏 1≤$\mu {}_\varphi $ < 1.41 76≤u < 114 中等破坏 1.41≤$\mu {}_\varphi $ < 5.28 114≤u < 152 严重破坏 5.28≤$\mu {}_\varphi $ < 8.28 152≤u < 190 完全破坏 8.28≤$\mu {}_\varphi $ 190≤u -
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