Abstract The paper concerns the importance of dynamic structure–soil–structure interaction (SSSI) for structures with two or more foundations. Firstly, analysis of such polypod foundations is performed in frequency domain, considering the range 0–50 Hz and employing Green’s function for wave propagation in layered soil. Normalised dynamic stiffnesses related to individual foundations and cross-coupling between two foundations are presented. To allow time-domain analysis, frequency-independent consistent lumped-parameter models (LPMs) are developed, proposing a criterion for determining which components must be included within an LPM to account adequately for the SSSI. While the methodology can be applied to polypods with any number of footings, the examples concern bipods with two footings or piles. However, the examples illustrate the methodology and prove its accuracy and efficiency. Firstly, the response is evaluated for monolithic masses placed on each foundation such that interaction can only occur via the soil. Secondly, a structure is introduced to examine and compare the coupling between the two foundations via the soil and via the structure. Different modes of dynamic SSSI are studied, finding that LPMs can provide nearly exact results for the considered problems, but with extremely few degrees of freedom compared to a finite-element model.

中文翻译：

---

多足地基的动态土-结构相互作用

摘要 本文关注动态结构-土-结构相互作用（SSSI）对于具有两个或多个基础的结构的重要性。首先，在频域中对这种多足类地基进行分析，考虑范围为 0-50 Hz，并采用格林函数在层状土壤中进行波传播。介绍了与单个基础和两个基础之间的交叉耦合相关的归一化动态刚度。为了进行时域分析，开发了与频率无关的一致集总参数模型 (LPM)，提出了一种标准，用于确定 LPM 中必须包含哪些组件以充分考虑 SSSI。虽然该方法可以应用于具有任意数量基脚的多脚架，但示例涉及具有两个基脚或桩的两脚架。然而，这些例子说明了该方法并证明了其准确性和效率。首先，评估放置在每个基础上的整体质量的响应，这样相互作用只能通过土壤发生。其次，介绍了一种结构，通过土壤和结构来检查和比较两个基础之间的耦合。研究了动态 SSSI 的不同模式，发现 LPM 可以为所考虑的问题提供几乎精确的结果，但与有限元模型相比，自由度极少。