地震下高墩刚构桥桥台背土相互作用分析方法对比
Comparison of analytical methods for the abutment-backfill interaction of a rigid frame bridge with high piers under seismic loading

针对重力式U型桥台背土相互作用，结合现行抗震规范，提出了4种分析模型及其力学本构关系和计算式。采用非线性时程法对比研究了某在建高墩双薄壁连续刚构桥的桥台背土相互作用效应。结果表明：只有弹簧模型可以求得与精细模型基本一致的高阶弹性模态；在纵桥向，滚轴模型和支座模型的结果都比精细模型小，弹簧模型相对精细模型的计算误差最小，关键内力误差不超过20%；在横桥向，支座模型的内力最接近精细模型，而弹簧模型和滚轴模型的结果都偏保守；桥台刚度对关键地震内力的影响幅度低于10%，而桥台有效参与质量的影响幅度也低于15%。综合考虑分析精度和计算成本，弹簧模型在抗震设计中更值得推荐。
Four analytical models are proposed for examining the effect of gravity abutment-backfill interaction based on current seismic design codes from home and abroad. The mechanical constitutive relationships as well as computing formulas are presented. Nonlinear time history method is applied to comparatively study the effect of abutment-backfill interaction on a rigid frame continuous bridge with double thin-walled piers, which is currently under construction. The results showed that only the spring model can obtain the closest higher-order elastic modes to those of the refined model. In the longitudinal direction, the results from the roller model and the bearing model are both much smaller than that of the refined model. The error of the spring model, compared with the refined model, is the smallest with the critical internal force errors not exceeding 20%. In the transverse direction, the bearing model is the closest to the refined model in calculating the internal forces, and both the spring model and the roller model predict conservative results with respect to that of the refined model. The influences of the abutment stiffness and effective participating mass on the critical seismic internal forces are smaller than 10% and 15%, respectively. Hence by comprehensively taking the prediction accuracy and computational cost into consideration, the spring model is the most suitable choice in seismic design of bridges.