Seismic Response Analysis Of Soil-Pile-Frame Structure Interaction

Study on dynamic soil-structure interaction has already become a hot and difficult problem in civil engineering and earthquake engineering. Theory of soil-structure interaction is still imperfect due to random and unpredictable of earthquake occurrence.Action relation of seismic soil-structure interaction is studied based on Haicheng Central Hospital. Through theoretical analysis and numerical simulation, dynamic constitutive model of the pile-soil interface has been established and a simplified analysis method of soil-structure interaction system is given. In order to study soil-structure interaction in structural dynamic, the whole process of Haicheng Central Hospital under different seismic waves is simulated by using ANSYS software. The main research content is as follow:Finite element model of Haicheng Central Hospital is simplified. Floor slab of underground structures is simplified as rigid floor. The aboveground structure is simplified as the beam and column system. Floor slab of aboveground structure is simplified as beam system with the reduction of mass and stiffness method. Constitutive model of soil element and structure in finite element analysis is determined through the contrastive analysis. Finite element model considering soil-structure interaction effects is established in ANSYS. At the same time, incremental iteration method is applied to solve nonlinear dynamic equations.The defect of tradition pile-soil interface model in ANSYS is analyzed and a improved two and three-dimension of the pile-soil interface model considering lift-off effect in dynamical action and energy loss between pile and soil is presented. The rigidity matrix of pile-soil interface contact element has been established. The improved pile-soil interface model is applied to an example. The results show that the improved pile-soil interface model is feasible for FEM numerical simulation of pile-soil dynamic interaction under seismic loading. Thereby, the result will be useful for the application of seismic response analysis in future.The improved pile-soil interface model is applied. At the same time, three-dimension finite element model considering soil-structure interaction effects of Haicheng Central Hospital under different seismic wave is simulated by using ANSYS software. Acceleration of the structure, displacement of the structure, stress variation of the underground structure and stress strain of foundation soil are analyzed. The analysis results show that, Tianjin wave has obvious effect on seismic response of Haicheng Central Hospital and seismic response of Haicheng Central Hospital is affected by man-made earthquake wave in little degree; the maximum displacement of the structure satisfy code for seismic design of buildings (GB50011-2010); the seismic performance of Haicheng Central Hospital is good; acceleration and displacement of the aboveground structure is larger than that of the underground structure; the maximum value of bending moment appears at the top of pile of the first layer of the underground structure and at the bottom of pile of the second layer of the underground structure which is the weak links of high-rise structure, thus, it should be considered highly during structural design.Base on the numerical simulation results of three-dimension finite element model considering soil-structure interaction effects of Haicheng Central Hospital and code for design of dynamic machine foundation (GB50040-96),simplified double-layer mass-damping-spring foundation model is established. The factors of quality of ground, shearing stiffness, freedom of soil and damping ratios are discussed and analyzed, a improved simplified multilayer-layer mass-damping-spring foundation model is established. A simplified analysis method of soil-structure interaction system is given.