A BEHAVIOURAL STUDY OF DYNAMIC SOIL STRUCTURE INTERACTION FOR PILED RAFT FOUNDATION WITH VARIABLE SUB SOILS BY TIME HISTORY FEM MODEL

Abstract

India is the developing country and in this age of rapid urbanization, geotechnical issues in construction of tall buildings are a major problem. These act as strong barriers against the construction of tall buildings in urban areas. Piled raft foundation is the type of foundation which can be used for the construction of tall buildings safely and economically. The piled raft foundation system has recently been widely used for many structures, especially high rise buildings. In this foundation, the piles play an important role in settlement and differential settlement reduction, and thus can lead to economical design without compromising the safety of the structure. Foundation rafts are analyzed as a plate on elastic foundation with the representation of the foundation media using the Winkler idealization. The elastic constant of the Winkler springs is derived using the sub-grade modulus. Perusal of literature reveals that very few investigations were done on the effect of variable sub soil on the behavior of structures supported on pile raft foundations. So in this research, an iterative dynamic analysis was performed using SAP2000 program to carry out three dimensional time history analysis of non-linear soil-foundation-building models under a great earthquake ground motions. The interaction between the soil and structure is represented by Winkler spring model. The obtained results confirmed that the dynamic characteristics of soil structure system should be recommended for conservative nonlinear seismic response of the high building since it mitigates of earthquake hazards.