弹塑性Winkler地基上双柱式桥墩的地震反应

浅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,地基土会进入塑性状态。要精确模拟上述两个问题是非常复杂的。分析中地基采用了能考虑基础提离及地基塑性的弹塑性Winkler地基模型,钢筋混凝土墩柱采用了武田三线型滞回模型。采用1940ElCentro地震记录作为输入,对双柱式浅平基桥墩进行了非线性时程分析。研究结果表明,基础提离和地基塑性对双柱式桥墩的地震反应具有重要影响。与线性分析相比,考虑基础提离和地基塑性后,双柱式桥墩的位移增大,内力减小。在设计中允许地基发生提离和屈服对于保护桥墩是有利的。

SEISMIC RESPONSE OF DOUBLE-COLUMN BRIDGE PIERS ON ELASTO-PLASTIC WINKLER FOUNDATION

For bridge piers with shallow foundation subject to intense earthquake excitations, the uplift of foundations occurs and the foundation soils enter into plasticity. It is rather difficult to simulate the uplift and yield of supporting soils accurately. An improved Winkler foundation model taking into account the uplift and yield of foundation is employed in the analysis. A tri-linear hysteretic model is employed in the analysis of reinforced concrete bridge piers. The El Centro earthquake record in 1940 is inputted to a double-column bridge pier with shallow foundation so that the nonlinear history response is obtained. It is concluded that the uplift and yield of supporting soil have important effect on the seismic response of double-column bridge piers. Compared with that of linear analysis, the displacement of the double-column piers increases and the internal force decreases. It is shown that the consideration of uplift and yield of foundation in design is significant in protection of bridge piers.