The Finite Element Analysis With Considering Interaction Between Superstructure And Base And The Optimization Of Raft Foundation

The interaction theory of the space superstructure-base-soil has made great progress, since it is developed to this day. And that,using this analysis theory, we can afford to improve the level and quality of foundation design and gain more economic effect. Firstly, effectively making use of the stiffness of superstructure, we can reach the scantling of structure of foundation to the least possible degree; if superstructure and foundation are considered as a whole, the height of coffer foundation,the thickness of raft foundation and the quantity of pile in piled raft foundation are diminished greatly. Secondly, for a main building and annex, that their layers and construction configurations are different from each other, usually, we select different configurable foundations, cautiously contrast them with interaction analysis and connect the base of a main building and annex with superstructure as a complete thing, to fulfill requirements in architecture function. Thirdly, taking advantage of interaction analysis to design soil and foundation rationally, reduce the internal force,settlement and cost of foundation to the smallest possible degree. As a design method of structure, interaction analysis should be made a study because its theory analysis and engineering practice are still in the primary stage.Based on serially discussing method of calculation of soil,foundation and superstructure and by the background of the Building Block 2 in ZiWei-uptown, the mechanics analysis model of the nonlinear whole finite element is established by the authors,and the model is calculated and analyzed largely in the method of simulation by finite-element program"ANSYS". According to the theory of the interaction among superstructure, foundation and soil, the subsoil, foundation and upper structure are researched and meshed as a whole in this paper. By the comparative and comprehensive analysis, we will reduce,(1)degree that conventional design method is different from interactional one in level displace of superstructure and internalforce of frame column,to supply references to safety and economy of structural design,(2)that characteristic under stress of superstructure,soil and foundation is analyzed with respectively changing the stiffness of each one,(3)that settlement deformation of raft on elasto-plastic base is assayed with the condition of merely transforming stiffness of superstructure,soil and foundation and increasing vertical load,number of floor and span,(4)the capability under stress and of deformation about raft foundation is gradually considered with translating extrorse length and concrete intensity grade of raft.By numerical value's simulation analysis,we get some major conclusion,(1)the level displacement and internal force of international design are bigger and more uniformizable than ones of conventional design method,(2)the stiffness of superstructure has a little effect on the force and displacement of superstructure,soil and foundation,however,the stiffness of foundation has a great impact on the internal force and displacement of three parts,the soil stiffness only has a deep influence on displacement,(3)the vertical load,number of strata and span largely influence uniform settlement and differential settlement of structure,(4)the extrorse length of raft has a certain extent influence on the internal force and displacement of base,comparing with this,the effect of concrete intensity looks little.