EQUIVALENT FIXED-BASE MODELS FOR SOIL-STRUCTURE INTERACTION SYSTEMS

To simplify the consideration of the soil-structure interaction (SSI) effects, a single degree-of-freedom (SDOF) replacement oscillator has been successfully utilized to represent an SSI system with SDOF struct ural model. In the present paper, this approximation is first extended to an equivalent fixed-base model with modified system parameters. Ba sed on this generalization, a methodology is then proposed to determin e the equivalent fixed-base models of a general multi degree-of-freedo m SST system using simple system identification techniques in the freq uency domain. Various fixed-base models are formulated and their accur acy is compared for a five-story shear building resting on soft soil. It is shown that the actual SSI system can be accurately represented w ith an appropriate fixed-base model. (C) 1997 Elsevier Science Limited .