The effects of variable soil damping on soil-structure dynamics.

This study examines the effects of variable dynamic dissipative and elastic soil characteristics on the dynamic response of a soil-structure system. Three equivalent linear modeling techniques (linear hysteretic and Kelvin-Voight constitutive models and weighted modal time history analysis) are used to incorporate the soil and structure’s unique dissipative characteristics. The soil’s critical viscous damping ratio and shear modulus are iteratively determined based upon experimentally observed, upper and lower bound strain-dependent stiffness degradation and damping curves. It is found that the three techniques produce consistent results: as the shear modulus increases, so does the primary natural frequency of the response; as the damping ratio of the soil increases, the magnitude of the response decreases. It is also found that variations in response due to using different values for a soil’s dynamic characteristics are dependent upon the equivalent linear modeling technique used. The impact of soil damping variability is seen to be as influential upon the dynamic response of a structure as shear modulus variability, because dissipative variations have a direct impact on the magnitudes of the displacement responses. The effects of variable soil damping should therefore be considered in addition to stiffness parameters as part of the dynamic characteristics of a system when determining a system’s dynamic performance. [ABSTRACT FROM PUBLISHER]