Finite Element Analysis Of Pile Raft Foundation Interaction Framework

With the development of economic, high-rise buildings spring up in largenumbers, promoting the progress of design methods, and the analysis of structureinteraction is an very important subject. the high-rise building structures have thecharacters such as multiplayer,high height,large weight.As structures built on softsoil or deep soil,using the traditional rigid foundation assumption withoutconsidering the effect of the interaction between the superstructure and substructureis unreasonable,there exists large difference between the calculation results and thepractical conditions. The actual buildings is connected to a whole one bysuperstructure, substructure,foundation,which influence and restrict each other undercertain loads. The study on structure interactions has been extended from nuclearpower plants, high-rise buildings, dams to large bridges, underground structures andlifeline engineering field,which has become one of the current geotechnicalengineering issues. In the high-rise building construction, owing to its excellentcharacteristics, raft foundation piles have been got more and more attention. Inconventional structural design, the upper frame structure, the ground and foundationare designed separately, without considering the interaction between the variousparts of the overall structure of the deformation coordination. However, in practicalengineering, the stress and deformation of the three parts affect each other, there is adisplacement equilibrium and the internal force redistribution in structure, that’s,they work as a whole part. Domestic and foreign scholars have made deep researchon how to consider the upper structure, the ground and foundation together, whichhas been widely used in practical engineering.In this paper, based on theoretical and finite element analysis, the interaction ofthe upper structure, the ground and foundation are studied. The basic theory of thecombined action and finite element model are introduced. The model was establishedby using the ANSYS finite element analysis software. The effect of the raft thickness,the frame layers, geological conditions and the stiffness of the concrete structure onthe structure deformation and forces are considered respectively. As the upper framestructure, the axial force, shear force and bending moment of the ground floorcolumns are more sensitive to the effects of the structure interaction. Therefore, it’snecessary to analyze the ground floor columns with the upper frame structure.Considering the effect of foundation rigidity on the structure interaction, raftfoundation thickness and concrete strength were taken into cosideration respectively.As to the effect of different geological conditions on the structure interactionanalysis, the elastic modulus of the soil and the soil cohesion are considered.Through the study of the interaction of the whole frame structure, axial force ofcolumns, moment of frame structure and frame beams, forces and settlement ofraft,piers axial force were analyzed. to study the structure of time in considering theinteraction of stress.With the conclusions the paper presented, it has importantguidance meaning to the design of pile raft foundation.