采用ECC和高强钢筋的刚构墩地震易损性分析

Seismic Vulnerability Analysis of Rigid Frame Piers with ECC and High Strength Steel Bars

为了明确工程用水泥基复合材料(Engineered Cementitious Composite, ECC)和高强钢筋对桥墩结构抗震性能改善效果,探讨ECC在桥墩中应用的可行性,利用OpenSees软件建立某连续-刚构桥刚构墩的非线性分析模型,在明确桥墩塑性铰区ECC替换高度和截面配箍率、高强钢筋替换率基础上,采用增量动力分析法(IDA)对刚构桥墩地震易损性进行分析评价.分析显示:塑性铰区ECC替换高度可按照曲率突变点确定;算例桥墩经济合理的体积配箍率为0.78%,桥墩全截面纵筋替换为高强钢筋时,RC/ECC桥墩墩底极限曲率提高12.4%,耗能能力平均提升22.5%;相比原设计,采用ECC和高强钢筋的刚构桥墩各极限状态对应的超越概率均有明显降低,抗震性能更优,地震损伤破坏风险显著降低,说明在桥墩中使用ECC和高强钢筋替代普通钢筋混凝土可行,且能有效改善桥墩地震响应.

In order to clarify the effect of engineered cementitious composite(ECC) and high-strength steel bars on seismic performance of bridge structure, to discuss the feasibility of ECC application in piers, a rigid pier non-linear analysis model of a continuous-rigid frame composite bridge is established by OpenSees software. Based on the determination of the replacement height of ECC in the plastic hinge area and the replacement rate of high-strength steel bars and stirrup ratio in the section, the rigid frame pier’s seismic vulnerability is analyzed and evaluated by incremental dynamic analysis(IDA). The results show that the replacement height of ECC in plastic hinge zone can be determined according to the curvature change point. The economical and reasonable volume stirrup ratio of the pier is 0.78%. The ultimate curvature of the RC/ECC pier bottom increases 12.4% when longitudinal steel bars of the pier are all replaced by high strength steel bars, and the energy dissipation capacity increases 22.5% on average. Compared with the original design, each limit state’s transcendence probability of the rigid frame pier with ECC and high-strength steel bars is significantly reduced. Its seismic performance is superior and the risk of seismic damage is significantly reduced. It shows that ECC and high-strength steel bar can reasonably replace ordinary reinforced concrete in bridge pier, and can effectively improve seismic response of bridge pier.