新型基底摇摆隔震桥墩柱抗震性能试验与分析

Experimental study and analysis on the seismic performance of new base rocking isolation bridge piers

基底隔震结构已成为当前国际上研究新型结构抗震性能和开发新型结构抗震体系的热点方向之一。该研究提出了一种通过增设加台和高阻尼橡胶垫块的新型基底摇摆隔震桥墩模型,介绍了该新型基底摇摆隔震桥墩的具体构造细节,阐述了该桥墩的减隔震原理和优点,并通过振动台试验得出了该新型桥墩能够显著降低墩顶水平加速度和墩底应力值,但同时会增大墩顶水平位移的结论;过大的墩顶水平位移会影响桥墩的正常使用极限状态,以墩顶水平位移为设计控制要点,考虑墩柱在实际摇摆提离过程中的加台受压区宽度和墩柱弯曲变形的影响,通过静力平衡条件建立墩顶水平地震力F与墩顶水平提离位移δ的力学关系式,并引入位移动力放大系数β考虑实际桥墩墩顶动力位移Δ,使得其墩顶水平位移Δ满足铁路桥梁规范墩顶允许位移5 L数值要求。通过对理论推导关系式进行验证,结果表明理论推导的力学关系式和数值模拟结果整体上符合较好,并分析了存在偏差的主要原因。

Base rocking isolation structures are one of the hot topics on the seismic performance of new structures and the development of a new type of structural seismic system.This paper proposed a new type of base swing isolation bridge pier model with the additional platform and high damping rubber bearing,and introduced the specific structural details of the new base rocking isolation pier,and elaborateds the seismic principle and advantages of the new base swing isolation bridge pier.Through a shaking table test,it is concluded that the new pier can significantly reduce the horizontal acceleration of the pier and the stress at the bottom of the pier,but at the same time increase the horizontal displacement of the pier.The excessive horizontal displacement of the pier top will affect the normal use limit state of the pier.The article takes the horizontal displacement of the pier as the design control point,considering the width of the compression zone and the bending deformation of the pier during the actual swinging and lifting process.Influence,the mechanical relationship between the horizontal seismic force F of the pier top and the horizontal lift-off displacementδof the pier top was established by the static equilibrium condition,and the displacement dynamic amplification factorβwas introduced to consider the dynamic displacementΔof the actual pier pier,so that the horizontal displacement of the pier top isΔ,which meets the numerical requirements of the allowable displacement of the pier top of the railway bridge specification 5 L.At the end of the paper,the theoretical derivation relation was verified.The results show that the theoretically derived mechanical relations and numerical simulation results are in good agreement,and the main reasons for the deviation were analyzed.