Exact Analysis of Raft Foundation Subjected to an Out-of-Plane Point Load
| International Journal of Civil Engineering |
| © 2017 by SSRG - IJCE Journal |
| Volume 4 Issue 7 |
| Year of Publication : 2017 |
| Authors : S.O. Ajayi, T.N. Johnarry, T.C. Nwofor |
10.14445/23488352/IJCE-V4I7P101
How to Cite?
S.O. Ajayi, T.N. Johnarry, T.C. Nwofor, "Exact Analysis of Raft Foundation Subjected to an Out-of-Plane Point Load," SSRG International Journal of Civil Engineering, vol. 4, no. 7, pp. 1-8, 2017. Crossref, https://doi.org/10.14445/23488352/IJCE-V4I7P101
Abstract:
Foundation rafts, in various aspects behave as plates or slabs. This study focuses on the case of surface point load for both deflection and stress convergence of series solutions.Resting on an elastic foundation, the behavior under load is influenced by the modulus of the sub-grade reaction of the soil. Several methods of analysis have been developed in the past to obtain plate solution;however, in this study, the main focus is to use a new method of analysis, “the curvaturedisplacement method”to achieve point load solution. To achieve this, the shape function for an all-round simply supported plate was adopted. This is because the slab is assumed to rest simply on heavy perimeter beams. The curvaturedisplacement method was used to obtain the equation for deflection, curvature and moment using nine series-terms where convergence error became negligible. The equations obtained were thereafter, used to estimate the result for deflection, curvature and moment for a simplified solution. These are the results needed for design of the slab. Results found were among the best in the literature and the particular case of moments at the point load giving a convergent result of 0.43P stands out.
Keywords:
Raft foundation, Elastic foundation, Curvature and displacement, Modulus and subgrade reaction.
References:
1) Clough, R. (1980), The Finite Element Method After Twenty-Five Years. Computers and Structures, 12, 361– 370.
2) Dolic´anin, C. B., Nikolic´, V. B. and Dolic´anin, D. C. (2010). Application of Finite Difference Method to Study of the Phenomenon in the Theory of Thin Plates. Scientific Publication of the State University of Novi Pazarvol 2, 29- 43.
3) James, B. D., (2005). A Finite Element Approach to Reinforced Concrete Slab Design. MSc Thesis, School of Civil and Environmental Engineering Georgia Institute of Technology.
4) Johnarry, T. N. (2011). Acceleration-Displacement Ratio Transform of Differentials for Transverse Plates and Constant Stiffness Buckling Solution. Journal of Innovative Systems Design and Engineering, 2(4), 250- 263.
5) Roger, T.F. (1996). Finite Element Methods for Engineers. London Imperial College Press.
6) Timoshenko, S. and Woinowsky-Krieger, S. (1959).
Theory of Plates and Shells. New York McGraw-Hill. 7) Winkler, E. (1967). Die Lehre von der Elastizita¨t und Festigkeit, Prague.
8) Zienkiewicz, O. C. and Taylor, R. L. (1999). The Finite Element Method, 5th Edition. Butterworth-Heinemann.