NUMERICAL ANALYSIS OF ENTIRE INTERACTIVE SYSTEM OF RAFT FOUNDATION CONSIDERING STRUCTURAL STIFFNESS EFFECT

Raft foundations are widely empolyed for high-rise buildings or multi-rise structures founded on soft ground.Therefore the interaction of superstructure,raft foundation and subsoil gets to be considerably significant in the analysis and design of major structures on soft ground with raft foundation.In actual,the conventional methods in engineering design cannot duly reproduce the interaction mechanism of the system and cannot accurately predict the variation characteristics of both internal forces and deformations of raft foundation.At the same time,the 2-D numerical analysis of interaction system cannot manifest the three-dimensional effect of the interaction.Therefore,both the elasto-plastic behaviour and the contributions of stiffness of superstructure and raft foundation are considered and three dimensional numerical analyses of interaction system consisting of superstructure,raft foundation and subsoil are conducted by using FEM.Through the comparactive studies,it is shown that while the spatial effect is taken into consideration,the stiffness of both superstructure and raft foundation has a definite effect on both internal forces and deformations of interaction system with different characteristics.However such an effect is limited to a certain extent.Furthermore,the effect of second stress and the transferring of loading sharing of superstructure cannot be overlooked in engineering design.