This paper presents a study on three-dimensional seismic soil–structure interaction analysis of a piled-raft (PR) foundation in clay by the substructure approach. Two different pile modeling techniques were adopted and compared with centrifuge shaking table test results reported in the literature. The effect of pile spacing on dynamic impedances, kinematic response parameters, axial pile forces and bending moments of PRs is studied. It is found that the presence of a rigid raft on a pile group results in significant variation in vertical and horizontal dynamic stiffness after a dimensionless frequency ([Formula: see text] value of around 0.22. The influence of raft on kinematic response parameters at the top of raft is found to be significantly influenced by pile spacing beyond a dimensionless frequency ([Formula: see text] value of 0.4. The axial forces generated at the pile heads of a PR–structure system during seismic shaking are quantified using a new dimensionless factor, and are found to be significantly influenced by the pile spacing. Pile layout in the PR system is found to play an influential role in seismic response as well as pile bending moment for a structure–PR–soil system studied.

中文翻译：

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粘土中桩筏的地震响应特性

本文采用子结构方法对粘土中的桩筏（PR）地基进行三维地震土-结构相互作用分析。采用了两种不同的桩建模技术，并与文献中报道的离心机振动台试验结果进行了比较。研究了桩间距对PRs的动态阻抗、运动响应参数、轴向桩力和弯矩的影响。研究发现，桩组上刚性筏板的存在导致在无量纲频率（[公式：见正文]值约为 0.22 后，垂直和水平动力刚度发生显着变化。筏板对运动学响应参数的影响在发现筏板顶部受到桩间距的显着影响，超过了无量纲频率（[公式：见文本]值为 0.4。地震震动过程中 PR 结构系统桩头处产生的轴向力使用新的无量纲因子进行量化，并发现其受桩间距的显着影响。研究发现，PR 系统中的桩布置对所研究的结构-PR-土系统的地震响应和桩弯矩具有重要影响。