Soil response in frequency dependent equivalent linear analysis

Abstract

One-dimensional equivalent linear site response analysis is widely used in practice due to its simplicity. The main limitation of the procedure is that it is essentially a linear method, in which the time dependent changes in the shear modulus and damping are ignored and constant values are assigned in the analysis, resulting in filtering of high frequency components of the ground motion. Modification of the equivalent linear analysis methods have been proposed to enhance the accuracy of the equivalent linear method by modeling the dependence of the shear strain with the loading frequency, often termed frequency dependent equivalent linear analysis (FDEL). This study used harmonic type and recorded motions to perform a series of site response analyses and to evaluate the accuracy of the FDEL through observation of the calculated shear stress-strain curves and transfer functions. The results demonstrate that the FDEL may generate artificial high frequency components of the ground motion, and hence should be used with caution.