Macro-model description and model verification

Abstract

The interaction between structures and soil is often idealized to simplify the problem. However, the soil structure interaction (SSI) is important for accurately predicting the mechanical behavior of foundations. Through the framework of macro-modelling, the SSI can be described within a single macro-element. The macro-element can be coupled with the structural analysis, thus simplifying the analysis and saving computational time.

The model presented is described with three degrees of freedom and based on plasticity-theory. The macro-model is calibrated with finite elements. Validation is done with the use of a small scale-foundation tested on medium grained and medium dense sand. This sand is subject to index- and triaxial testing to get representative parameters for the Hardening Soil-model used for calibration.

The performance of the macro-model and its applicability for a shallow foundation anchoring large eccentric forces are investigated. Comparison shows that the model is able to reproduce the mechanical behavior quite well and is deemed satisfactory for describing the behavior of the foundation, although some modifications are suggested. The mechanical behavior is somewhat stiff (attributed to a high shear modulus) and the capacity in the M/B-H plane is slightly underestimated.