This paper derives an exact analytical solution for determining elastic critical buckling pressures and mode shapes for very long corroded cylindrical steel shells subjected to external pressure considering symmetrical and anti-symmetrical mode cases. The corroded long cylindrical shell has been modelled as a non-uniform “stepped-type” ring consisting of two portions- corroded and un-corroded regions. A full range parametric study has been made to investigate the effect of corrosion angular extent and corrosion thickness on the elastic buckling pressures and their modes. The study shows that buckling loads and modes depend on the corrosion angular extent â and the corroded to un-corroded thicknesses ratio. The results are verified by a set of investigations with a series of corroded cylindrical shells. They showed a close agreement with those obtained from using the finite element package ABAQUS
