AN IMPROVED 2-SPRING MODEL FOR FOUNDATION UPLIFT ANALYSIS

Abstract

In many cases of seismic analysis of building structures with foundation uplift, the Winkler foundation model or an equivalent two-spring model is used to represent the interaction between a foundation mat and soil. The analysis using the Winkler foundation model provides a more accurate prediction while it requires a complicated procedure and longer computation time than that using an equivalent two-spring model. An efficient equivalent two-spring model (S model) for the prediction of the seismic response of building structures with foundation uplift is proposed in this study. The S model can represent the Winkler foundation model with accuracy and the analysis procedure using the S model is simpler and more effective than that using the Winkler foundation model. The S model is derived from the Winkler foundation model by simplifying the nonlinear moment-rotation relationship of the foundation mat. The seismic responses predicted by the S model and the Winkler foundation model are in good agreement even when uplift is significant.