%0 Journal Article
%T Effect of Dynamic Soil-Structure Interaction on Raft of Piled Raft Foundation of Chimneys
%A B. R. Jayalekshmi
%A S. V. Jisha
%A R. Shivashankar
%A S. Soorya Narayana
%J ISRN Civil Engineering
%D 2014
%R 10.1155/2014/790928
%X This paper presents numerical analysis of soil-structure-interaction (SSI) of tall reinforced concrete chimneys with piled raft foundation subjected to El Centro ground motion (1940) using finite element method. Seismic analysis in time domain was performed on the basis of direct method of SSI on the three-dimensional SSI system. The chimney, foundation, and soil were assumed to be linearly elastic in the analysis. The stress resultants and settlement of raft of piled raft foundation were evaluated under different soil properties and different geometrical features of raft and chimney. Soil properties were selected based on the shear wave velocity corresponding to sand in the loose to dense range. Chimneys with different elevations of 100£¿m, 200£¿m, and 400£¿m were taken with a ratio of height to base diameter of chimney of 17. Raft of different thickness was considered to evaluate the effect of stiffness of foundation. Results were analysed to assess the significance of characteristic of the ground motion. It is found that the response in the raft depends on the different parameters of chimney, foundation, and soil. It is also found that the higher modes of SSI system are significant in determining the response in the raft. 1. Introduction Most of the analysis of piled raft foundation neglects the effect of geometrical and material features of the superstructure. Generally the loads and moments from the superstructure to foundation are only considered for the analysis of foundation. The shape and size of the superstructure such as chimney have their own significance to determine the responses in foundation. Chimneys are tall and slender structures with tapering geometry. Analysis of such kind of chimney-foundation system that rests on soil which is of unfavorable geotechnical conditions will be too complex especially when it is subjected to earthquake ground motions. The present study deals with the seismic analysis of chimney with piled raft foundation considering the flexibility of soil in time domain. 2. Background of the Problem Very few studies have been carried out in the area of dynamic analysis of soil-piled raft-structure interaction compared to that of soil-pile-structure interaction [1¨C3]. Field measurements were taken by Yamashita et al. [4] to understand the static and seismic behavior of a piled raft foundation which is supporting a 12-story base-isolated building in Tokyo from the beginning of the construction to 43 months after the end of the construction. During the monitoring period of the building, Tohoku Earthquake (2011) struck the
%U http://www.hindawi.com/journals/isrn.civil.engineering/2014/790928/