Seismic Bearing Capacity of Strip Footing with Nonlinear Mohr–Coulomb Failure Criterion

Abstract

Many published studies on seismic conditions have focused on a pseudostatic method with a linear Mohr–Coulomb failure criterion. However, the pseudostatic method ignores the influence of time and spatial variables on seismic accelerations, and almost all soils have nonlinear strength properties rather than linear properties. Herein, a new approach was established for calculating the seismic bearing capacity that considers a linear distribution of the seismic coefficients. A nonsymmetrical failure mechanism and the nonlinear Mohr–Coulomb failure criterion were used to describe the collapse process and soil properties. A layerwise summation method was developed to calculate the work rates because the pseudodynamic method depicts the variation in seismic acceleration as well as the time and spatial variables. In this work, a first application for calculating the seismic bearing capacity of soil foundations with nonlinear strength properties was conducted using the kinematic approach of limit analysis. Based on the numerical results and discussions, the key conclusions were as follows: (1) the reliability of this approach was verified by making exact comparisons with theoretical results and lab data; (2) in general, nonlinear solutions were more conservative than linear solutions; and (3) a high value of initial cohesion c0 resulted in an increase in the seismic bearing capacity qlim, and qlim decreased when the ratio of tensile strength σt to initial cohesion c0 or the value of nonlinear parameter m increased for a given value of initial cohesion c0.