An improved formulation for the assessment of the capacity load of circular rings and cylindrical shells under external pressure. Part 1. Analytical derivation

In this two-part set of articles the capacity load of circular rings under external pressure is investigated assuming as a starting point the classic LevyTimoshenko approach, which is still at the bases of most design codes for cylindrical shells. This first paper presents a perfected analytical formulation of the problem, which accurately accounts for the onset of plasticity and incorporates the effect of various geometrical imperfections. A rigorous non-linear formulation is first derived and, subsequently, an algebraic expression which avoids the recourse to numerical solution strategies is established.