Dynamic Soil-Structure Interaction

The report provides a method for a simple extension of response-spectrum procedures in seismic building analysis to include dynamic soil-structure interaction. The analysis utilizes soil impedance functions for a structural foundation. Most of the computational results refer to a rigid mat foundation. The damping that arises in a soil-structure system will generally be nonclassical. A rapid approximate scheme is developed for computing nonclassical modes of a soil-structure system. The computation, which is extremely effective, uses a classical mode of the structure with its base fixed. The differences of the initial and improved modes give direct measures of the significance of the interaction effects. The response-spectrum approach, which is the most reasonable and convenient for the case of classical damping, is found to be applicable to a soil-structure system~ including the nonclassical damping that is present. Several examples are presented to demonstrate the capability of the solution method.National Science Foundation Grants ENV 77-07190 and PFR 80-0258