COMPUTER AIDED ANALYSIS OF CONTINUOUS R C. C4 FOOTINGS

Abstract

Continuous footing is generally used as foundation for industrial buildings, godowns, ware houses etc, where a number of columns are laid in one line. The purpose is to bridge over soft soil pockets and to reduce the differential settlement between adjacent columns. For the safe and optimal design of the footing it is very much essential that the internal stresses viz shearforce, bending moment•and deflection at every section of the footing are evaluated as accurately as possible. To achieve this objective an analysis of continuous R.C. footing using FINITE DIFFERENCE APPROACH has been outlined. The analysis has been programmed and a package has been developed in TURBO-C language which is compatible to any IBM machine. The package is interactive, user friendly and menu-driven. It uses window input and output facility. Results are displayed inside windows on the computer screen. To help the user it also displays context sensitive help for each and every input data item. TURBO-C graphics facility has been used for plotting deflection, shearforce, bending moment diagrams and winklers foundation-loading model. The package developed can analyse continuous footings loaded with concentrated loads as well as moments at column positions. Moment of Inertia of the footing as well as soil stiffness may vary along the footing length. The package has been used to solve a number of numerical problems to bringout: 1) The effect of loose soil pockets. 2) The effect of the stiffness of the footing. 3) The effect of water table fluctuations below footing. 4) The effect of moment loading on the footing. The results show that the loose soil pockets located at the ends of the footing affect the deflection and bending moment distribution significantly and hence their effect cannot be ignored for safe design. Stiffening of the footing below columns doesnot affect the deflection and bending moment distribution significantly. Further, we observe that moment loading of outer columns of the footing has appreciable effect on deflection and bending moment distribution.