System parameters of soil foundations for time domain dynamic analysis

Abstract

Abstract Soil‐structure interaction analysis is usually carried out in the frequency domain, because the compliance functions of the half‐space are known only in the frequency domain. Since non‐linear analysis cannot be carried out in the frequency domain, a system with frequency independent parameters is used to represent the half‐space soil medium so that a nonlinear analysis in the time domain becomes possible. The objective of this paper is to propose a system with lumped parameters, which are independent of frequency, to represent the half‐space soil medium. The proposed frequency independent system consists of a number of real discrete structure elements; thus the existing dynamic analysis programs may be adoptable with little modification. In this paper, the parameters are found by minimizing the sum of the squares of deviations between the steady‐state responses of the theoretical half‐space model and those of the lumped parameter system over a specified frequency range. Once the parameters have been found, the lumped parameter system can be used in practical applications for time domain dynamic analysis of either linear or non‐linear structures. In comparison with the dynamic response of the theoretical half‐space model, the lumped parameter system yields satisfactory results.