不同构造下的预制拼装钢管混凝土桥墩抗震性能试验

Experimental Analysis of Seismic Performance of Precast Assembled Concrete Filled Steel Tube Piers Under Different Structures

为探讨预制拼装钢管混凝土桥墩抗震力学性能,充分发挥预制拼装钢管混凝土桥墩的抗震能力,以实际桥墩为参考,考虑不同拼装接缝形式、耗能钢筋配筋率和预应力轴压比等参数,设计和制作了6个摇摆式预制拼装预应力钢管混凝土桥墩和2个对比墩(1个摇摆式预应力钢筋混凝土墩和1个承插式预应力钢管混凝土墩),共8个缩尺模型。采用拟静力试验方法,结合数值模拟揭示预应力预制拼装钢管混凝土桥墩的延性能力、自复位性能、滞回耗能特性、破坏模式和破坏机理。试验结果表明:对于2种构造下的钢管混凝土桥墩,摇摆式桥墩因其可发生一定范围内摇摆,并设置预应力筋和耗能钢筋,使其延性与耗能能力更加优异;在墩底设置UHPC座垫层,加载过程中其对承台的破坏相对较小,提高了桥墩的损伤容限;在相同的目标位移下,摇摆式试件残余位移小于承插式试件,表明摇摆式预制拼装钢管混凝土桥墩拥有良好的自复位特性;对于摇摆式预制拼装钢管混凝土桥墩,增大耗能钢筋配筋率,使得试件损伤状态出现滞后,耗能能力增强,减轻墩底接缝破坏程度,同时使得残余位移增大;增大预应力轴压比,其约束试件变形的自复位能力进一步增强,使试件残余位移减小,有利于桥墩在震后功能的快速恢复;通过建立各试件的有限元纤维模型,进一步验证了试验结果的准确性。研究成果可为后续预制拼装钢管混凝土桥墩的设计与应用提供试验基础。

In order to explore the seismic mechanical properties of precast concrete-filled steel tube piers and give full play to the seismic capacity of precast concrete-filled steel tube piers, six rocking precast prestressed concrete-filled steel tube piers and two contrast piers(one rocking prestressed reinforced concrete pier and one socket prestressed concrete-filled steel tube pier) were designed and fabricated, taking the actual piers as reference, considering the different assembling joint forms, the reinforcement ratio of energy-consuming bars and the axial compression ratio of prestress, with a total of eight scale models. Based on the quasi-static test method and numerical simulation, the ductility, self-centering, hysteretic energy dissipation, failure mode and failure mechanism of prestressed precast concrete-filled steel tube piers are revealed. The test results show that: for the concrete-filled steel tube piers with two kinds of structures, the rocking pier has better ductility and energy dissipation capacity because of its rocking within a certain range and the setting of prestressed tendons and energy-consuming bars;the UHPC cushion is set at the bottom of the pier, the damage to the bearing platform is relatively small during the loading process, which improves the damage tolerance of the pier;under the same target displacement, the residual displacement of rocking type specimen is smaller than that of socket type specimen, which reveals that the rocking precast prestressed concrete-filled steel tube piers are in possession of good self-centering characteristics. For the rocking precast concrete-filled steel tube pier, increasing the reinforcement ratio of energy-consuming bars will make the damage state of the specimen lag, enhance the energy dissipation capacity, reduce the damage degree of the pier bottom joint, increase the residual displacement, and increase the prestressed axial compression ratio, so as to reduce the constraint. Finally, the accuracy of the test results is further verified by establishing the finite element fiber model of each specimen. The research results can provide a test basis for the design and application of precast concrete-filled steel tube piers.