Simplified Earthquake Analysis of Multistory Structures With Foundation Uplift

Abstract

A simplified analysis procedure is developed to consider the beneficial effects of foundation‐mat uplift in computing the earthquake response of multistory structures. This analysis procedure is presented for structures attached to a rigid foundation mat which is supported on flexible foundation soil modeled as two spring‐damper elements, Winkler foundation with distributed spring‐damper elements, or a viscoelastic half space. In this analysis procedure, the maximum, earthquake induced forces and deformations for an uplifting structure are computed from the earthquake response spectrum without the need for nonlinear response history analysis. It is demonstrated that the maxr imum response is estimated by the simplified analysis procedure to a useful degree of accuracy for practical structural design.