探讨了提离式基础对城市高架桥抗震的适用性.基于上海嘉闵线典型两跨高架桥,考虑桩土非线性相互作用,建立了OpenSees全桥动力计算模型.对比分析了提离桩和普通桩基础在不同墩高和地震动强度下的地震响应,以单桩内力响应、桩基配筋率、桩基位移、残余位移作为评价指标评估了提离桩的适用性.结果表明,提离式桩基础通过释放桩头拉力,避免了不利的拉弯受力状态,可以显著降低桩基的配筋需求;尤其对于中、高墩状况,提离桩的性能检算主要由单桩最大竖向承载能力控制;提离式桩基础的最大桩顶水平位移略大,但水平残余位移较小,表明其更好的震后自恢复性,两种基础的最大竖向位移和竖向残余位移基本相当.%The applicability of rocking pile-group foundations in the design of urban viaducts was focused.Based on a typical two-span elevated bridge on the Jiamin road in Shanghai,two finite element models with rocking and conventional pile-group foundations were developed respectively using the OpenSees platform,considering the nonlinear soil-pile interaction.The seismic responses of the two types of foundations were analyzed with various pier height and excitation intensity,and then the applicability of the rocking pile-group foundations for urban viaducts was evaluated by taking the critical pile seismic forces,the longitudinal reinforcement,and the maximum and residual displacements at the pile top as the evaluation indices.The results show that the loading state of unexpected large tensile force combined with larger bending moment can be prevented by using the rocking pile foundation and consequently the longitudinal reinforcement ratio is significantly reduced.The seismic safety of the rocking pile-group foundation is primarily governed by the maximum vertical load bearing capacity of the piles.Though the rocking pile-group foundation leads to relatively larger maximum horizontal displacements at the pile top,smaller residual displacements resulted by the rocking pile-group foundation indicates a better resilient performance.Both the two types of pile foundations lead to similar maximum and residual vertical displacements.
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