ABSTRACT
A cylindrical wall subjected to uniformly distributed vertical prestress, at mid-wall surface, or to linearly varying circumferential prestress, with top and bottom edges free to rotate and translate in the radial direction, is an example of a case where creep, shrinkage and relaxation gradually change the distribution of stress in the concrete and the reinforcements, without change in stress resultants. However, when the edge displacements are restrained, the internal forces also change with time. A cylindrical wall, having free top edge and bottom edge supported on bearing pads, providing an elastic support, is an example of a frequently occurring case where the magnitude of the reaction at the elastic support and the bending moment due to circumferential prestress undergo significant variations with time. Important time-dependent variations of internal forces can also occur in a tank due to differences in ages of concrete in the base, the wall and the cover; this is due to differential elasticity moduli, creep coefficients and magnitudes of shrinkage.
