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以汶川大地震中倒塌的某钢筋混凝土刚架拱桥为例,采用杆端塑性铰模型、反应谱分析、弹性时程分析和动力弹塑性分析方法对其进行地震响应分析。根据两阶段抗震设计思想,确定表达两阶段水平的反应谱,选择了3组具有3个方向完整记录的地震地面加速度时程历史和1条人工地震波。研究结果表明:多跨连续钢筋混凝土刚架拱桥结构复杂,振型频率密集,振型参与质量分布离散;考虑桩-土-结构共同作用后,刚架拱桥在地震作用下结构内力和截面塑性转角增加;基础的非对称水平位移改变了结构的振动特性,显著增加基础水平抗推刚度较弱一侧主(次)拱腿的地震力和塑性变形,加剧了地震破坏作用。研究结论为多跨连续钢筋混凝土刚架拱桥抗震性能评估提供参考依据。
Taking a reinforced concrete rigid frame arch bridge collapsed during the Wenchuan earthquake as an example, the seismic response analysis was carried out using the plastic hinged rod model, response spectrum analysis, elastic time history analysis and dynamic elasto-plastic analysis. According to the two-stage seismic design idea, the response spectra of two stages of expression are determined and three sets of seismic ground acceleration time histories with complete records in three directions and one artificial seismic wave are selected. The results show that the structure of multi-span continuous rigid-frame CFST arch bridge is complex, the frequency of vibration modes is intensive, and the vibration modes are involved in the mass distribution. Considering the joint action of pile-soil-structure, the structural internal forces and plastic transition angles The basic asymmetric horizontal displacement changes the vibration characteristics of the structure and significantly increases the seismic force and plastic deformation of the main (secondary) leg on the weak side of the basic level of anti-push stiffness, which aggravates the earthquake damage. The research conclusion provides a reference for the seismic performance evaluation of multi-span continuous rigid-frame arch bridge.