外置耗能器对自复位预制RC桥墩抗震性能的影响研究

以中国已建成的首座震后自复位桥梁-京台高速（北京段）黄徐路跨线桥为背景，结合自复位结构和装配式结构的特点，发展自复位预制RC桥墩新型结构。设计并制作对桥墩抗侧强度贡献率分别为0，20%及40%的3组外置耗能部件，并对3组自复位桥墩进行水平拟静力往复试验研究。通过桥墩变形和损伤演化过程、力-位移滞回曲线、骨架曲线、试件耗能能力、预应力筋张拉力变化、残余位移、接缝开口和受压区高度变化等评估自复位预制RC桥墩的抗震性能及外置耗能器对其影响。研究结果表明：外置耗能器耗能段均出现明显的高阶屈曲形态，耗能作用明显，附加外置耗能器自复位桥墩的滞回曲线呈明显的“旗帜”形；耗能器的抗侧强度贡献率越高，墩柱的滞回曲线越饱满，墩柱的耗能能力和抗侧承载力也明显提高；加载至偏移率3.5%时，自复位预制墩柱抗侧承载力无明显下降，表现出良好的延性性能；随墩顶水平位移增加，墩柱内轴向预应力筋张拉力基本呈线性增加，建议墩内竖向预应力筋初始张拉力不超过名义屈服强度的70%；为保证自复位墩柱具有较小的残余位移，建议附加外置耗能器对桥墩的抗侧贡献率不宜超过40%。研究可为自复位预制RC桥墩的结构设计、数值模型验证和工程实践提供参考。

Study on the Effect of Exterior Dampers on the Seismic Performance of Self-centering Precast Bridge Columns

A novel type of self-centering prefabricated bridge column(SC-PBC)was developed based on the first self-centering(SC)bridge in China,the Huangxu road overpass bridge of the Beijing-Taiwan expressway(Beijing section),combined with the characteristics of the selfcentering and fabricated structures.Three groups of external energy dissipation devices(EDDs)with contribution rates of 0,20%,and 40% to the lateral strength of the bridge column were designed and manufactured.A horizontal quasi-static test of the three groups of SC-PBC with EDDs was carried out.The seismic performance and influence of the EDDs on the SC-PBC were evaluated by the deformation and damage evolution process of the bridge columns,the forcedisplacement hysteresis behavior,skeleton curve,energy dissipation capacity,tension force of the prestressing tendons,residual displacement,joint opening,and compression zone height at the pier bottom.The results showed that:obvious high-order buckling behavior occurs in the energy dissipation section of the EDD during loading,revealing obvious energy dissipation;the hysteretic curves of the SC-PBC model with external EDDs exhibit an obvious"flag"shape;with the increase of the contribution rate of the lateral strength of the EDDs,the hysteretic curves of the piers are plumper,and the energy dissipation ability and lateral strength of the pier are obviously improved.When the lateral displacement is 3.5%,the lateral strength of the SC-PBC with external EDDs does not decrease significantly,which indicates good ductility;the tension force of the axial prestressing tendons in the SC-PBC increased linearly with an increase in the horizontal loading displacement at the top of the bridge column;the initial tensile force of the prestressing reinforcement of more than 70% of the nominal yield strength is not recommended;and to ensure the small residual displacement of the SC-PBC,EDDs with a contribution rate of more than 40% to the lateral strength are not recommended.This research provides a reference for the structural design,numerical model validation,and engineering practice of the SC-PBC.