SSI效应对大跨高墩桥梁弹塑性地震响应的影响

Effects of SSI on the elasto-plastic seismic response of long-span and high-rise bridge

基于大型有限元分析软件ANSYS,根据大跨高墩桥梁的结构特点,利用水平和转动弹簧单元建立了考虑土结相互作用的大跨高墩桥梁的有限元计算分析模型,并结合现行的《铁路工程抗震规范》,合理地选取强震记录作为地震动输入,进行了大跨高墩桥梁的弹塑性地震响应分析。分析结果表明:较软的土质条件会导致大跨高墩桥梁弹塑性地震响应的增大;地基系数的比例系数则是影响数值计算结果增大的重要因素;土结构相互作用并没有改变地震动峰值加速度PGA对超高桥墩弹塑性地震响应的影响。研究结果可为大跨超高桥墩的抗震设计和验算提供参考。

According to the characteristics of long-span and high-rise bridge, the soil-structure interaction was taken into account by using horizontal and rotational spring elements and the finite element analysis （FEA） model was established based on the ANSYS software. Meanwhile, reasonable strong seismic motion records were selected according to the applicable Code of Seismic Design for Railway Engineering, and the nonlinear time history analyses for elasto-plastic seismic response of long-span and high-rise bridge considering soil - structure interaction were car- ried out. The study results are obtained as follow：the flexible soil condition can lead to the enlargement of seismic response ; The proportionality factor of foundation coefficient is an important factor which will enlarge the result ; The effect of PGA on elasto-plastie seismic response of long-span and high-rise bridge is not affected by the soil - struc- ture interaction. The resuts give a reference to seismic design and checking calculation of super high-rise pier.