Discussion of "Buckling of Thin-Walled Silos and Tanks under Axial Load-Some New Aspects" by Martin Pircher and Russell Q. Bridge

The formation of circumferential imperfections resulting from welding is readily understandable. The resulting shell deformations are perceived to be similar to those described by Esslinger et al. for a cylinder with a shrunk ring. In the case described by the authors, the weld tension zone approximates the ring. Without going into a detailed discussion of the Esslinger et al. paper, suffice it to say that one of the equilibrium conditions that had to be met was that 'the transverse shear force in the shell equals the radial force on the ring.' These forces translate into compression in the shell and tension in the ring. Similarly, in the case described in this paper, these forces translate into compression in the shell and tension in the tension zone.