Study on the analysis of mat foundations with special reference to thick shell finite element

Abstract

In recent years mat foundations are widely used in tall buildings. There are a number of methods for analyzing mat foundations. These are the Conventional Method, ACI Approximate Flexible Method and Discrete Element Methods viz. Finite difference method, Bowles Finite Element Method, and Finite Grid Method. All these methods developed so far are based on several assumptions and idealisation of mat on soil. There are some cases where these methods fail i.e., mats of irregular shape with cut-out sections, notched ends, irregular ecentric colunm loading and certain architectural constraints. In these cases the alternative is to use the thick shell finite elements. In this study mats are analyzed using 8 nodal parabolic thick shell finite elements. Although a mat is a plate-type structure, but in cases where mat is subjected to inclined loads, a shell element will give better representation. The soil-mat interface is idealised by discrete soil springs and the soil reaction is computed using the modulus of sub grade reaction. A generalized computer program, developed by Ahmad, is capable of handling arbitrary geometry, loading and boundary conditions as well as variable thickness. A number of mats analyzed by thick shell finite elements have been studied for desired results. A comparative study of these results and those obtained from other methods is done. The thick shell finite elements give more logical results than the other methods paving the path for further research in this field.