Analysis of Circular Tank Foundations
by C. V. Girija Vallabhan, F.ASCE, (Prof., Civ. Engrg. Dept., Texas Tech Univ., P.O. Box 4089, Lubbock, TX 794091023) and Y. C. Das, M.ASCE, (Visiting Prof., Civ. Engrg. Dept., Texas Tech Univ., P.O. Box 4089, Lubbock, TX)
Journal of Engineering Mechanics, Vol. 117, No. 4, April 1991, pp. 789797, (doi: http://dx.doi.org/10.1061/(ASCE)07339399(1991)117:4(789))
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Document type: 
Journal Paper 
Abstract: 
The analysis of axisymmetric circular tank foundations has been made in the past using the classical Winkler model, where the properties of the elastic foundation are modeled by one parameter, k, called modulus of subgrade reaction. Even though many recommendations have been made for the value of k, the model yields erroneous results, because the value of k depends on the depth of the soil stratum with respect to the size of the slab as well as to the distribution of the loading. Also, the elastic properties of the soil can vary within the soil stratum. Assuming that the elastic properties of the soil stratum are constant or linearly varying in the vertical direction, and that the stratum rests on a rigid surface, a simple, more accurate mathematical model is developed here. Two parameters are used to represent the elastic foundation, and an iterative technique is introduced to obtain a consistent energy solution. The finite difference method is employed to get the solutions. The loading can be either uniform or axisymmetric lateral pressure, axisymmetric live load, or moments at the edge. The slab or plate at the bottom of the tank should be flexible enough to satisfy the assumptions of the linear plate theory. The results of an example tank problem with different types of loadings are compared with more exact finite element solutions. 
