Strength determination for band-loaded thin cylinders

Cylindrical shells are often subjected to local inward loads normal to the shell that arise over restricted zones. A simple axisymmetric example is that of the ring-loaded cylinder, in which an inward line load around the circumference causes either plasticity or buckling. The ring-loaded cylinder problem is highly relevant to shell junctions in silos, tanks and similar assemblies of shell segments. The band load is similar to the ring load in which a band of inward axisymmetric pressure is applied over a finite height. When the height is very small, the situation approaches the ring-loaded case, and when the height is very large, it approaches the uniformly pressurised case. This article first thoroughly explores the two limiting cases of plastic collapse and linear bifurcation buckling, which must both be fully defined before a complete description of the nonlinear and imperfection-sensitive strengths of such shells can be described within the framework of the European standard for shells (EN 1993-1-6). Finally, the application of the reference resistance design (RRD) over the complete range of geometries for the perfect structure is shown using the outcome of the limiting cases.