The Finite Analysis For The Seismic Response Of Pile-raft Foundation-soil-frame Structure System Under Cooperative Effects

The earthquake is an abrupt natural disaster and makes huge damage to human community. The Wenchuan earthquake of 12 May 2008 still cause much emotional suffering now. In the recent years, there have been a certain number of experiments and studies on the problem of interaction between soil and structure. But because of the complication of this issue, many research scholars study different areas and more analysis and researches are needed for the dynamic interaction of soil and structure in earthquake.Based on the domestic and foreign correlation theories and method, the dynamic finite element method is used to analyze the model which simulates the interaction of soil and structure in earthquake. The main works and results are listed as following:(1) The parameters of 3D-FEM-earthquake model are summarized comprehensively and detailed, including the element selection, the artificial boundary conditions, the seismic inputting method, the damping and so on.(2) The 3D-FEM-earthquake models of frame structure with twelve floors are set up in ANSYS to perform mode analysis and dynamic time-history analysis. Compared with the condition without soil, the affection of the interaction of soil and structure on the cycle, the displacement and the shear are given. The largest displacement occurred on the top floor, but the maximum relative displacement occurred on the bottom. The change low of shear is discussed. Considering the interaction of soil and structure, the greatest shear is at the bottom, and then the shear diminishes with increased floor. So the bottom layer of frame structure should be strengthen in anti-seismic design.(3) Without changing the total building area, the plane-form of frame structure has been changed so as to compare the responses-of frame structures in different plane forms, under seismic condition, and study how the plane forms exert impacts on the seismic resistant capacity of frame structure. The conclusion is given that the regular and symmetrical structure have better anti-seismic ability. The conclusions can be used for the anti-seismic design of structure.