Due to the stress dependent nature of the material properties of soil, it can be difficult to find a comprehensive approximate method that captures all features of the response of a structure or foundation under dynamic loading. For this reason, a fundamental problem in soil-structure interaction was investigated, both experimentally by means of centrifuge modeling, and computationally using boundary element methods. The problem consisted of a circular surface foundation resting on a soil stratum, subjected to random loading applied at a vertically eccentric location on the upper surface of the footing. The experimental data was compared with computational results for two soil material models: A soil with an equivalent homogeneous shear modulus, and a two-zone soil model that more directly accounts for the stress dependence of the soil’s material properties. The two-zone model represents the far-field using a shear modulus that has square root dependence with depth, and a local homogeneous zone directly underneath the footing. Computational and experimental results were also compared with a previous study involving square footings on a soil stratum, having contact pressures equal to the circular footings in this report
