A model analysis of stresses in the wall and floor of a cylindrical steel tank

Abstract

The assumption of a fixed base condition for the analysis of wall stresses is justified only in the case of a rigid support, when the fixed-end moment is small.

By evaluating the constants of the deflection equation for the wall at any given point, the variation of stress along the wall and the rotation of the base can be determined. It should be noted that for larger values of x, when the effect of the (Bx)-functions begins to die out, the constants become more dependent on any slight variation of the observed stress. Thus, a choice of several readings would have been desirable in the region where x does not exceed the value of 3λ/2. Strain readings at higher points serve mainly to test their relative accuracy and as a check on the B-value, but not to determine the constants.

A comparison of stresses along the floor would be extremely difficult, if not meaningless, since one would have to depend on the mechanical accuracy of the model in order to evaluate the boundary conditions for the floor. A direct analysis of the floor stresses is not advisable in the case of a small model, since irregularities in the manner of support influence these stresses greatly. The theoretical approach to stress-evaluation for the bottom plate resting on a rigid foundation, has been discussed by R. Hofmann (9) for the particular case where Poisson’s Ratio is equal to zero. No derivation of formulas has been given in the paper.