灌浆套筒和预应力筋连接的预制拼装桥墩的抗震性能

针对轨道交通预制拼装桥墩的受力特点, 提出了采用灌浆套筒和预应力筋连接的拼装方案; 设计了3种不同类型桥墩, 包括整体现浇试件(RC)、预应力钢绞线和灌浆套筒连接的预制拼装试件(PCSS) 与精轧螺纹钢筋和灌浆套筒连接的预制拼装试件(PCTS), 采用拟静力试验方法分析了各种桥墩的各种拟静力指标, 比较了桥墩的抗震性能。试验结果表明: PCSS和PCTS试件的各指标非常接近, 最大误差为2.2%;灌浆套筒会使传统塑性铰区上移至套筒顶部, 说明灌浆套筒对传统塑性铰区域具有局部增强作用, 建议对塑性铰的箍筋加密区高度应额外增加1个套筒高度; 采用预应力筋使试件的混凝土轴压力增大了1倍, 相应的开裂荷载也增大了约1倍; PCSS试件的屈服荷载和极限荷载正负向均值比RC试件分别提高了31%和34%, 等效屈服位移、极限位移和偏移率均值分别比RC试件提高了17%、13%、13%, 但是PCSS试件的延性系数平均降低了10%;在偏移率为6%时, PCSS试件的残余位移均值是RC试件的61%, 显示了较好的自复位能力; 与RC试件相比, PCSS试件的刚度提高了13%。相比于精轧螺纹钢筋, 钢绞线可以适当弯曲与成束, 面积调整灵活, 因此, 采用无黏结预应力筋和灌浆套筒连接的桥墩试件具有良好的使用性能和抗震性能, 可作为预制拼装轨道桥墩的推荐方案。 

Seismic performance of prefabricated assembled pier with grouted sleeve and prestressed reinforcements

According to the mechanical characteristics of prefabricated assembled piers for rail transit, the assembly scheme of grouted sleeve and prestressed reinforcements was put forward.Three different types of piers were designed, including the integral cast-in-place reinforced concrete specimen (RC), the prefabricated and prestressed concrete specimen with strands andgrouted sleeves (PCSS), and the prefabricated and prestressed concrete specimen with screw thread steel bar and grouted sleeve (PCTS).The evaluation results of various pseudo-static evaluation indicators for each type of bridge pier were analyzed by using pseudo-static test method.The seismic performances of various kinds of piers were compared.Test result shows that the indexes of PCSS and PCTS are very similar, and the maximum error is 2.2%.The grouted sleeve shifts the traditional area of plastic hinge up to the top of grouted sleeve, so it shows that the grouted sleeve has local reinforcing effect on the traditional plastic hinge region, and the height of plastic hinge stirrup is advised to add extra one height of grouted sleeve.The concrete axial pressure of specimen increases by 1 time when using prestressed reinforcements, and the corresponding cracking load also increases by approximate 1 time.The mean values of yield load and ultimate load of PCSS are 31% and 34% higher than those of RC, respectively.The average equivalent yield displacement, ultimate displacement and drift ratio are 17%, 13%and 13% higher than those of RC, respectively, but the ductility factors of PCSS decreases by10%.At the same drift ratio of 6%, the mean residual displacement of PCSS is 61% of RC, which shows better re-centering capacity.Compared with RC, the stiffness of PCSS increases by13%.Compared to screw thread steel bar, steel strands can be bent and bundled, and the area is flexible to adjust.So the bridge pier specimens with unbonded prestressed reinforcements and grouted sleeve have better operation and seismic performance, and can be served as the recommended scheme for prefabricated assembled rail pier.