允许提离的弹塑性Winkler地基上桥墩的地震反应

SEISMIC RESPONSE OF BRIDGE PIERS ON ELASTOPLASTIC WINKLER FOUNDATION ALLOWED TO UPLIFT

钱平基桥墩在承受强震作用时，其基础与地基之间会发生提离，地基上会进入塑性状态。要精确模拟上述两个问题是非常复杂的。本文分析中采用了能考虑基础提离及地基塑性的弹塑性Winkler地基模型，采用1940EICentro地震记录作为输入，对法平基桥墩进行了非线性时程分析。研究结果表明，基础提高和地基塑性所产生的非线性行为是非常明显的。考虑基础提离和地基塑性后，桥墩—地基系统的刚度不断退化，基础转角明显增大，而基底弯矩明显减小。

We the bridge piers with shallow foundation are subject to intense earthquake excitations, uplift of foundations will occur and the foundation soils will enter into plashcity. It is very difficulty to simulate the uplift and yielding of supporting soils using an accurate method. An improved Winkler foundation model, which could be used to consider uplift and yield was employed in the analysis. The 1940 El Centro earthquake record was inputted to a rigid bridge pier with shallow foundation so that the nonlinear history response was obtained. It is concluded from the nonlinear analysis that the nonlinear effect is very remarkable when uplift and yielding of supporting soil are considered Compared with the linear analysis, the stiffness of bridge rier-soil system degrades in each cycle after considering uplift and yielding. The nonlinear analysis shows larger rotational response and smaller bending moment than those of the linear analysis.