Stability of column-supported steel cylinders with engaged columns

Abstract

Steel silos are often supported on a small number of columns to facilitate emptying operations. The connection between these columns and an elevated cylindrical metal silo shell is a long-standing difficult problem in shell analysis. The presence of local supports beneath a cylinder leads to stress concentrations in the cylindrical wall just above the supports, which can cause buckling or plastic collapse and consequently failure of the entire structure. Engaged columns produce a gentler introduction of the support forces into the cylindrical shell and cause a smoother stress distribution above the column termination. Engaged columns are therefore a very practical solution for local supports. In practice, smaller silo structures are often supported on engaged columns attached to the side of the shell, but very few investigations of the structural behaviour or the strength of such an arrangement have ever been made. In this paper, the structural behaviour of a cylinder supported on engaged columns is investigated, including the effects of geometric imperfections and geometric nonlinearity. The study is conducted using the requirements for computational evaluations set out in EN 1993-1-6 (2007) and using the finite element package ABAQUS. The columns are assumed to be flexurally and axially rigid to provide a clear scientific study of the failure behaviour of the cylinder under these conditions.