Load-bearing capacity of discretely supported steel silos shells with skirts

Local concentrations of meridional compressive stress in the cylindrical shells of steel silos in many cases lead to loss of stability of these shells. Preventing such situations is a fundamental challenge to designers. Standard EN 1993-4-1 allows for inappropriate analysis of the phenomenon of local stability loss in longitudinally compressed cylindrical shell supported discretely through a skirt. To prevent uneven distribution of compressive stress along the circumference of such shells standard EN 1993-4-1 proposes use of a skirt with thickness 20% higher than the thickness of the shell. This proposal is wrong since even this thick skirt cannot provide even distribution of stresses. The paper presents the results of nonlinear numerical analyzes of several cylindrical shells modeled with imperfections (GMNIA). Several solutions of support regions were analyzed. It has been shown that the capacities of analyzed shells are lower than those of uniformly supported shells with the same parameters.