Dimensional Analysis of Linear Soil-Foundation-Structure System Subjected to Near-Fault Ground Motions

This paper investigates in depth the dynamic responses of soil-foundation-structure systems using dimensional analysis in order to evaluate the significance of soil-structure interaction effects when subjected to near-fault ground motions. A soil-foundation-structure interacting (SFSI) system is idealized into a simplified 2DOF system where linear structures with flexible foundations are considered. Through rigorous dimensional analysis, the response of superstructure is presented in terms of the dimensionless Π-terms. This approach brings forward the self-similarity, the invariance with respect to changes in scale or size, which decisively describe the interactive behavior of a foundation-structure system. Extensive simulations have been conducted on various SFSI systems subjected to pulse-type ground motions to numerically describe the structural response, i.e. dimensionless relative displacement, as a function of distinctive properties of superstructure; foundation and input motion. Results show that soil-structure interaction is insignificant for a variety of structure-foundation systems in practice. However, there are conditions under which the response of foundation-structure system is significantly higher than that of the fixed-base structure.