An Assessment of the Effects of Structure/Raft/Soil Interaction

This paper is used to study the effects of interactive analysis of rafted framed structures founded on inhomogeneous soil by using different section moduli pf the superstructure, different raft thicknesses and different effective stress elastic mo duli of the soil.The interactive analysis of rafted framed structures founded on inhomogeneous soil media generally requires the use of a large computer, and is expensive. In this paper a much more economical simplified method to analyse these structures, which was developed by King and writer Yao in The Structural Engineer, September, 1983, is used. A typical long-rafted space frame is then analysed. Some intersting results which are very useful for design are obtained from the interactive analysis.First, when the relative section rigidities of the superstructure are varied by using different section sizes, the effects of the differential settements of the foundation are small. But the influence of the forces in the superstructure is significant.Secondly, when the relative rigidity of the raft is varied by using different raft thicknesses properly, both the effects of the differential settlements of the foundation and ths forces in the superstructure are significant. But for this type problem if the increasing of the raft thickness is too much, the effects are small and is expensive. However, the forces in the raft are varied significantly with the varying of the raft thickness.Thirdly, when the effective stress elastic moduli of the soil are varied, the effects of the total settlement of the building are significant. But the influence of the forces in the superstructure and raft and the differential settlements are small.