Small-Strain Shear Modulus and Damping Ratio Models for Southeastern US Residual Soil and Saprolite Considering Loading Frequency

This study develops frequency-dependent predictive models for small-strain shear modulus and small-strain material damping ratio using resonant column and torsional shear tests by other investigators on six specimens of southeastern US residual soil and saprolite. The specimens are characterized as nonplastic silty sand to sandy silt. The stepwise regression modeling considers loading frequency, confining stress, unit weight, plasticity index, fines content, moisture content, and grain size characteristics. The results show that confining stress is the most significant factor influencing shear modulus, which agrees with previous studies. Loading frequency is the most important factor influencing material damping, but has been included in relatively few previous empirical models. Total unit weight is the next most influential factor after confining stress and loading frequency. The new models can adjust the measured small-strain shear modulus and small-strain damping to desired conditions for loading frequencies greater than 0.1 Hz.