SOIL=STRUCTURE INTERACTION USING SIMPLIFIED MODELS

Abstract

It is well appreciated fact from the past that consideration of soil flexibility is an important issue that should be included in dynamic analysis of structures. Soil flexibility in dynamic analysis is a major issue, because of the complexity in modelling the soil medium. The present study focuses on inclusion of soil flexibility in dynamic analysis using simplified models. A thorough study has been carried out on some of the simplified models, their concept, formulations and methods. It is required to study the effects of the parameters governing the simplified models for better understanding the behaviour of these models. tb Numerous methods exist for consi r t foundation flexibility in design. Out of these, a method (Wolf, 1994), exists in-which soil foundation system can be represented by equivalent springs and dashpots, which are derived using simple physical models. This method is an alternative to the rigourous models which are tedious and uneconomical. Simplified models with one-dimensional free-field analysis allow surface and embedded foundations to be analysed which leads to results with provides remarkable agreement with rigourous methods. An attempt has been made in this dissertation to study and understand some of the simplified models used in dynamic soil-structure interaction analysis. Some of the parameters i.e. frequency dependent characteristics, boundary conditions, embedment of foundation, stratum depth and material properties of soil, which effects these models are studied. The study shows that free-field motion, kinematic interaction and dynamic stiffness highly demonstrate the dependency on frequency contents. It is also seen that kinematic interaction is negligible for surface foundation. There is significant effect of depth of embedment and stratum depth on kinematic interaction and impedance function.