Abstract Evaluation of the impedance functions and internal forces in various modes of vibration form an important step in the design of pile supported structures subjected to dynamic loads. This study tries to assess the variation in impedance functions and load distribution characteristics when a ground contacting pile cap is introduced over single and group piles. A substructuring method-based soil structure interaction (SSI) analysis model is employed to study vertical and horizontal dynamic impedances of piled rafts (PR) in homogeneous and layered soil conditions. The amplitude and phase of the dynamic interaction factor, signifying the interaction between the raft and pile group for various PR area ratios and soil conditions are evaluated. For the 2 × 2 piled rafts analysed, the dynamic load sharing between pile and raft is found to be frequency dependent in the vertical mode and practically frequency independent in the horizontal mode.

中文翻译：

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动力荷载作用下桩筏基础的刚度和分担特性

摘要 各种振动模式下的阻抗函数和内力的评估是受动荷载的桩支撑结构设计的一个重要步骤。本研究试图评估在单桩和群桩上引入接地桩帽时阻抗函数和载荷分布特性的变化。采用基于子结构方法的土壤结构相互作用 (SSI) 分析模型来研究均质和分层土壤条件下桩筏 (PR) 的垂直和水平动态阻抗。评估动力相互作用因子的幅度和相位，表示各种 PR 面积比和土壤条件下筏和桩组之间的相互作用。对于分析的 2 × 2 桩筏，