Dynamic modeling and response of rigid embedded cylinders

Following a brief review of the limitations of a popular technique for modeling the soil action in analyses of the dynamic response of deeply embedded cylindrical foundations and structures, the sources of the limitations are identified and a modification is proposed which, while retaining the attractiveness of the original model, defines correctly the action of the system. In the proposed approach, the soil medium is modeled by a series of elastically constrained, rather than unconstrained, thin horizontal layers with a circular hole at the center. The impedances of the constrained layers are established and are then used to evaluate the dynamic response of a rigid vertical cylinder embedded in a uniform viscoelastic stratum of constant thickness and infinite extent in the horizontal direction. The cylinder and the stratum are presumed to be supported on a non-deformable base undergoing a uniform horizontal motion. The effects of both harmonic and earthquake induced ground motions are considered. The response quantities examined include the dynamic force per unit of cylinder height and the corresponding base shear and base moment. The system investigated simulates the design of underground storage tanks at Hanford for the storage of radioactive wastes