COMPUTER-AIDED DESIGN OF RAFT FOUNDATION FOR MULTISTOREYED BUILDINGS

Abstract

Introduction Framed structures are commonly used in the construction of buildings and industrial structures. The conventional practice considers the isolated behaviour of structure during its analysis and design. In reality, however, supporting soil-foundation system alters the behaviour of superstructure and hence the need for considering the mutual interaction. Statement of Problem A simplified analysis of a framed structure founded on combined footing is done by considering typical plane frames in both the directions. Results of 2-D analysis from both the directions are thus combined to ensure full loads coming onto the columns are correctly estimated. The frame is idealised as an assemblage of column and beam elements resting on links. Iterative analysis is used to include the interaction of substructure and soil. with the superstructure. The analysis yields shears and bending moment coming onto the foundation beams for design purpose. Aim The. aim of this investigation is to propose a suitable method for iterative analysis of frame-footing-soil system so as to estimate the total and differential settlements and the extent to which the superstructure behaviour is altered by the supporting soil mass so that the frame and footings could be properly designed. Analysis The method of analysis should, be such as to iii Consider frame-footings and soil mass as an integral compatible unit and Consider the relative stiffness between structure and footings and that between footings and soil mass with these two points in view. A computer program based on stiffness matrix method incorporating the proposed method of analysis is used. Design of base slab and beam of cellular raft is also included in the above program