Finite Element Analysis For Interaction Of Superstructure, Raft Foundation And Soil

Reaserch on the interaction of superstructure-raft foundation-soil has beenextended from such fields as nuclear power stations, high buildings, dams to large spanbridges, underground structures and also fundamental projects. Research on thesuperstructure-raft foundation-soil has became one of spots in the field of rock and soilengineering and civil engineering. Actual building is an integrity system constituted bysuperstructure,foundation and soil, and they are influenced by each other. But In regulardesign, the superstructure whose bottom was considered as being fixed on thefoundation is analysed. Apparently this approach was unground for the real situation,especially during earthquake so the design was unsafe or uneconomical. Therefore, it iscrucial to develop a practical, effective and reliable theory and numerical analysismethod. Thus, it is key to understand the mechanism interaction of superstructure-raftfoundation-soil, and to modifythe regular design at the present.In this paper, research at home and abroad has been summarized on the interactionbetween superstructure, raft foundation and soil.First of all, it has discussed that the mechanism interaction of superstructure-raftfoundation-soil, analysed the forming of rigidity of superstructure, raft foundation, soil,and results, and expounded the computational analysis model and analytical method intheory. Then, the relevant conclusion can be concludes by finite element analysis inwhich we select the suitable 2- dimensional and 3-dimensional model. Main analyticalwork has been done as followed:1. To analyse the influencing of the forming of rigidity of superstructure,foundation, soil on internal force of interaction and deformation, under the function ofloading of the gravity, through the finite elementANSYS modeling.2. To analyse by ANSYS model, the influencing of intensity of concrete, thicknessof it under the gravity upon the raft foundation. We conclude to choose the analysis ofthe basic ground material of raft foundation rationally while carrying on the basicstructural design of the raft foundation. The results show that: the basic thickness ofthe raft foundation and material type have consistency to influencing by strengthperformance of raft foundation, and the grade of intensity of concrete of the raftfoundation should not be lower than C30.3. To analyse the earthquake reaction to on the interaction of superstructure-raftfoundation-soil. The interaction of structure system is analysed under the rigidity soiland flexible soil condition and change such factors as top structure rigidity , foundationparameter ,then discuss the dynamic interaction effect. The result of calculationindicates: the deformationis of structure is more obvious than the rigidity soil under theflexible soil condition. And there exists redistributed nature in internal forces under theflexible soil condition, and the changes of rigidity of top structure, foundation haveinfluence on internal force and deformation in interaction system. Finally, we have put forward several questions to be further investigated.aftersumarry.