INTERNAL FORCES ANALYSIS OF TALL BUILDING STRUCTURE FOUNDATION CONSIDERING STIFFNESS BOTH THE BASE AND PILES

In this paper the combined work of raft foundation, box foundation of high builcling structure with the base and piles is discaussed. Which is regarded as spatial forced system and analysised by finite element method. This paper uses static condensation idea and commands the lumped freedom degree of foundation concertion with freedom degree of base and piles at the joint place, then derived the lumped stiffness matrix of foundation. At the same time, derived two additional stiffness matrixes of foundation while the semi-infinite spatial elastic base and piles jointly work with foundation. Thus set up the global stiffness equation which shows the deformation coordination of foundation with base and piles. Dependent upon it we can calculate the subside quantity of foundation. Then calculate the internal forces and stresses of foundation considering the stiffness of base and piles using the formulas derived in this paper.