On the performance of lumped parameter models with gyro-mass elements for the impedance function of a pile-group supporting a single-degree-of-freedom system

摘要

Lumped parameter models with a so called "gyro-mass" element (GLPMs) have been proposed recently in response to a strong demand for efficiently and accurately representing frequency-dependent impedance functions of soil-foundation systems. Although GLPMs are considered to be powerful tools for practical applications in earthquake engineering, some problems remain. For instance, although GLPMs show fairly close agreement with the target impedance functions, the accuracy of the transfer functions and the time-histories of dynamic responses in structural systems comprising GLPMs have never been verified. Furthermore, no assessment has been performed on how much difference appears in the accuracy of dynamic responses obtained from GLPMs and those from conventional Kelvin-Voigt models comprising a spring and a dashpot arranged in parallel with various frequency-independent constants. Therefore, in this paper, these problems are examined using an example of 2x4 pile groups embedded in a layered soil medium, supporting a single-degree-of-freedom system subjected to ground motions. The results suggest that GLPMs are a new option for highly accurate computations in evaluating the dynamic response of structural systems comprising typical pile groups, rather than conventional Kelvin-Voigt models.