A comparison of experimental and theoretical investigations of embedment effects on seismic response

A research program has been conducted to both gain insight into the effects of embedment on the seismic response of nuclear power plant containment structures and to verify current analytical methods for the prediction of their seismic response. Tests were performed on small wooden cylinders, rectangles, and cubes using a shake table to conduct parametric studies in the effects of geometry, height to diameter ratio and amount of embedment. Additionally, an attempt was made to correlate the experimental results with simplified and finite element models that included both embedment and nonlinear effects. The results reported in the paper are applicable to cases where the foundation materials under and around the structure are similar. Both the analytical and experimental work indicate that the effect of embedment can be incorporated into the seismic analysis of structures by simple models. In particular, embedment effects can be neglected during seismic excitations if the depth to-diameter ratio is less than 0.5. For deeper embedment good agreement with experimental results can be achieved with simplified models and by selection of soil parameters evaluated at the appropriate strain levels. (Auth.)