A macro-element model for non‐linear soil–shallow foundation–structure interaction under seismic loads: theoretical development and experimental validation on large scale tests

In this paper different formulations of a macro-element model for non-linear dynamic soil-structure interaction analyses of structures laying on shallow foundations are first reviewed, and, secondly, a novel formulation is introduced which combines some of the characteristics of previous approaches with several additional features. This macro-element allows one to model soil-footing geometric (uplift) and material (soil plasticity) non-linearities, that are coupled through a stiffness degradation model. Footing uplift is introduced by a simple non-linear elastic model, based on the concept of effective foundation width, while soil plasticity is treated by means of a bounding surface approach, in which a constant vertical load mapping rule is implemented. This mapping is particularly suited for the seismic loading case, for which the proposed model has been conceived. The new macro-element is subsequently validated using cyclic and dynamic large-scale laboratory tests of shallow foundations on dense sand, namely: the TRISEE cyclic tests, the PWRI and CAMUS IV shaking table tests. Based on this comprehensive validation process against a set of independent experimental results, a unique set of macro-element parameters for shallow foundations on dense sand is proposed, which can be used to perform predictive analyses by means of the present model.