| Now, the structure seismic calculation methods is separate the superstructure and replacing foundation with fixed support, get the internal force and deformation of the superstructure and the support reaction, then use of the result to design the piles and check the foundation strength and deformation. This method ignores the deformation and displacement of foundation, engineering practice shows that the internal force of the superstructure calculated by the simplified method have big difference with the actual structure, especially at the bottom of structure. It is necessary to consider the interaction of foundation and structure in engineering. At the present stage, the theory of the interaction of subsoil foundation and superstructure is mainly based on the spring-damping-mass model and the elastic half-space model. Because of the complexity of these two methods and the limitations of practical engineering application, rigid foundation assumption is still used in the project.In this paper, a simplified calculation method is adopted to consider the interaction of subsoil foundation and superstructure, this method ignore the effect of foundation damping and assumed that foundation is the vertical spring with certain rigidity and soil around basement is horizontal spring with certain rigidity. All this springs are in elastic phase and have compressive stiffness only. In addition, because of the friction between the base and the soil and lateral restraint of pile foundation, horizontal displacement will not happen at the bottom of foundation.The paper puts forward calculation method of stiffness of single pile and soil spring and analysis of the shear wall structure with different aspect ratio in using dynamic elastic time history analysis. Calculate the structures with different foundation stiffness and study the effect on structure. Research shows that with the decrease of foundation stiffness, the natural period increase and the overall stiffness of the structure is reduced. The foundation stiffness has a significant influence on the structural displacement response, the more difference of foundation stiffness the more obvious influence. Horizontal earthquake action tends to decrease after considering the foundation stiffness, but there will be a negative impact on the local floor. Considering the foundation stiffness will increase the vertical seismic response.In this paper, the influence of the foundation stiffness on the overall overturning of the structure is studied. Considering the foundation stiffness will increase the rotation of the structure and have adverse effect on overturning stabilities. In order to describe the extent of the overturning of the structure under earthquake, the concept of the eccentricity is proposed. The eccentricity of the structure decreases with the decrease of the foundation stiffness. The influence of the number of basement layers on the overturning of the structure is also discussed and the paper presents the necessity of checking the structure overturn under medium earthquake. |
