Model Predictions of Dynamic Response of an Embedded Footing

A shallow foundation, 3 × 3 m in plan and embedded 0.9 m, was dynamically loaded at the National Geotechnical Experiment Site (NGES) on the campus of Texas A&M University (TAMU), and the measured results were compared with results computed via four widely publicized methodologies: the cone models of Wolf and Deeks, the PILAY models of Novak and Aboul-Ella, and the homogeneous half-space models for embedded footings of Apsel and Luco and Gazetas. The cone models produced the best predictions of the measured field response, and all four methodologies produced good predictions of the vertical and horizontal motions of the foundation. The rocking motions were well predicted using cone and half-space models, while the PILAY predictions of rocking were quite different from the measurements. The Gazetas model results suggested that full embedment and full contact of the foundation and soil produced the best representation of the field behavior. It was possible to find one representative half-space modulus for the models to match the field measurements for all modes of vibration, but it was not obvious how one would determine this modulus value a priori in a design situation and without the benefit of field response measurements.