Settlement of shallow strip footing on granular soil under eccentric static and cyclic loads

Abstract

The traditional way of analyzing the behavior of shallow foundations is based on applying the load to the center of the footing, but this is not always the case in practice. The settlement of a strip footing resting on dense sand under eccentrically applied static and cyclic loads is studied in this paper to find out the foundation’s behavior in realistic conditions. During cyclic loading, the shear modulus of the soil is changed, due to which the stiffness of the soil and footing response are greatly affected. Under the influence of cyclic loading, in coarse-grained soil, the strain accumulates depending on the intensity of the cyclic loading. In low-intensity cyclic load conditions, the accumulated strain reaches a constant value after a finite number of load cycles. In this study, the analysis of settlement is carried out with the help of a numerical technique, based on Beam on Nonlinear Winkler Foundation (BNWF). The parameters, namely, static load, the intensity of the cyclic load (qd(max)), the depth of embedment of footing (Df) and the eccentricity ratio (e/B) are varied to observe the effect of the cyclic reversal of the load on the foundation’s response. Using the simulation results of 144 model conditions, an empirical equation is proposed to estimate the total settlement of the footing using Multivariate Adaptive Regression Splines (MARS). The analysis of the numerical results and a parameter-sensitivity study suggest that the settlement under combined eccentric static and cyclic loads is mainly controlled by the existing static load.