CSI Software models soil-structure interaction using a one-parameter Winkler soil model. Soil modeling is demonstrated in the example problem, Beam on elastic foundation, available within the software interface through Help > Contents and Index > Example Problems > Problem J. This example problem, along with the hyperlinks below, present the concepts and techniques associated with modeling soil-structure interaction.
One modeling feature useful to soil-structure interaction is the gap (compression-only) link object, which enables foundation uplift without the development of tensile forces. Note that gap objects exhibit nonlinear behavior, and therefore require a nonlinear load case during analysis.