Seismic Bearing Capacity of Shallow Strip Foundations on Dry Soils

Abstract

Based on the kinematic approach of yield design theory, a method for the evaluation of seismic effects on the ultimate bearing capacity of shallow foundations on Mohr-Coulomb soils has been developed and successfully tested for both theoretical and experimental results. A new kinematic mechanism has been introduced, allowing for the uplift of the foundation under strong load eccentricities. An empirical formula which approximates the results of the kinematic approach has been derived for a simple investigation of the effects of inclination and eccentricity of seismic actions, as well as of soil inertia. The importance of these effects on the reduction of bearing capacity is discussed thoroughly, leading to the conclusion that soil inertia plays a negligible role compared to the seismic actions transmitted by the structure. Furtherly, taking load eccentricity into account in a pseudo-static approach may lead to very high safety factors in the design of shallow foundations.