Discrete element method simulations of the seismic response of shallow foundations including soil-foundation-structure interaction

A novel three-dimensional particle-based technique utilizing the discrete element method is proposed to analyze the seismic response of soil-foundation-structure systems. The proposed approach is employed to investigate the response of a single-degree-of-freedom structure on a square spread footing founded on a dry granular deposit. The soil is idealized as a collection of spherical particles using discrete element method. The spread footing is modeled as a rigid block composed of clumped particles, and its motion is described by the resultant forces and moments acting upon it. The structure is modeled as a column made of particles that are either clumped to idealize a rigid structure or bonded to simulate a flexible structure of prescribed stiffness. Analysis is done in a fully coupled scheme in time domain while taking into account the effects of soil nonlinear behavior, the possible separation between foundation base and soil caused by rocking, the possible sliding of the footing, and the dynamic soil-foundation interaction as well as the dynamic characteristics of the superstructure. High fidelity computational simulations comprising about half a million particles were conducted to examine the ability of the proposed technique to model the response of soil-foundation-structure systems. The computational approach is able to capture essential dynamic response patterns. The cyclic momentrotation relationships at the base center point of the footing showed degradation of rotational stiffness by increasing the level of strain. Permanent deformations under the foundation continued to accumulate with the increase in number of loading cycles. Copyright (C) 2011 John Wiley & Sons, Ltd.