Performance of Rocking Shallow Foundations and the Evolution of Beam-on-Nonlinear-Winkler Foundation Modeling

Abstract

The nonlinear behavior of shallow bridge and building foundations under large-amplitude seismic loading is an important aspect of performance-based earthquake engineering. Soil yielding beneath foundations can be an effective energy dissipation mechanism; however, this yielding may lead to excessive permanent deformations. The research and engineering community has established decades of model testing and analytical modeling to understand foundation nonlinearity and uplift. Physical model testing provides insight into the mechanisms at work in rocking, shallow foundations, while analytical modeling and simulation are validated against these experiment results such that modeling recommendations can be applied in practice. This body of work led to the current design procedures in industry, such that the benefits and consequences of foundations allowed to rock under seismic events can be understood and implemented in practice generally for design of proposed structures, as well as retrofit of existing structures. While there are various established analytical modeling approaches, this paper presents a summary of both the elastic and nonlinear Winkler analytical modeling approaches used to approximate observations from experiment, the status of codified design procedures incorporating rocking, and includes speculation on the future of research and design in this field.