Earthquake ground motion simulation with frequency-dependent soil properties

A one-dimensional earthquake ground motion simulation with frequency-dependent dynamic soil parameters, which include shear wave velocity and quality factor, is performed within the frequency band between 10−2 and 30 Hz. For the simulation, the general frequency-dependent dynamic soil properties are obtained by using a new non-resonance technique on various soils. Comparisons between transfer functions involving frequency-dependent and -independent dynamic soil parameters indicate that soil amplification throughout the considered frequency range is sensitive to the values of the dynamic soil parameters, in particular to the quality factor. Simplification of frequency-dependent dynamic soil parameters into constants, which prevail as a convenient practice, incurs large amplitude distortion. This study therefore demonstrates that the dynamic properties of soils play an important role in the near surface earthquake ground motion analyses and need to be used in the same way as how they were measured.