Analysis of soil-structure interaction system based on mixed branch mode and constrained mode two-step method

In order to introduce the effect of nonlinear soil-structure interaction during the structure design process,based on the branch mode synthesis method and the mixed linear-nonlinear constrained mode synthesis method,the mixed branch mode and constrained mode method suitable for non-linear soil-structure interaction system is proposed.The material nonlinearity of structure and soil could be considered effectively by using this method,and it is easier to inspect the influence of soil-structure interaction on superstructure.Furthermore,a mixed two-step method is also proposed on the basis of the mixed branch mode and constrained mode method and applied to the seismic analysis of soil-frame interaction system.The results indicate that the mixed two-step method could analyze superstructure and soil separately in consideration of material nonlinearity of structure and soil.This method is also beneficial to consider the effect of soil-structure interaction by only analyzing the superstructure model while using the professional design programs.It provides convenient method to consider the effect of soil-structure interaction during practical engineering calculation.