Effect of structure-to-foundation mass ratio in analytical modeling of soil-foundation-structure interaction during earthquakes

Abstract

The vertical factor of safety (FSv) of shallow foundations has been widely used for static design and seismic design. The FSv is a function of the bearing capacity of the system and the vertically applied load from the structure and foundation loads to the soil and foundation interface. However, the structure-to-foundation mass ratio (MR) can be different for the systems presenting the same FSv. The dynamic responses of the structure and foundation system depend on the MR as it develops dissimilar inertial behaviors from the structure and foundation. In this study, the effect of MR on the structure and foundation responses was evaluated using an analytical model that enables influence of the nonlinearity of the soil on the modeled foundation base and structure. For systems with the same FSv under identical input loading conditions, the inertial behavior of heavy foundations had a larger acceleration response than the lighter foundations. Consequently, MR should be considered for evaluating dynamic soil-foundation-structure interaction problems.