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为分析地震作用下大型桥梁高桩基础的运动特性,首先以苏通大桥5号桥塔的基础为工程对象,建立土层-桩基础相互作用体系的有限元模型。然后结合苏通大桥5号桥塔基础所在场地,以采用滞后阻尼模型条件下苏通大桥5号桥塔处自由场的地震动响应为基准,讨论了如何在有限元程序中合理考虑土层在地震激励条件下的阻尼特性。最后在此基础上确定土层-桩基础相互作用体系有限元模型的阻尼参数,并进行基岩一致水平激励下的桥梁桩基础承台的地震响应分析。数值结果表明,桩基础承台的运动以刚体运动为主,可用水平方向上的刚体平动,两侧承台中心处的竖向刚体平动和刚体转动来近似描述。
In order to analyze the motion characteristics of high-pile foundation under large earthquake, the foundation of the fifth tower of Sutong Bridge is taken as the engineering object to establish the finite element model of the soil-pile foundation interaction system. Based on the ground motion response of the free field of No.5 bridge tower of Sutong Bridge under the condition of hysteresis damping model, the paper discusses how to consider the influence of soil layer in the finite element program Damping characteristics under earthquake excitation. Finally, the damping parameters of the finite element model of the soil-pile interaction system are determined and the seismic response analysis of the bridge pile foundations under the uniform horizontal bedrock excitation is carried out. The numerical results show that the motion of pile foundation cap is mainly rigid body, which can be approximated by rigid body translation in the horizontal direction and vertical rigid body translation and rigid body rotation at the center of both sides of the cap.