Collapse behavior and strength of steel silo transition junctions. Part I: Collapse mechanics

Elevated steel silos commonly consist of a cylindrical shell, a conical hopper, and a skirt. At the intersection of these shell segments, a ring is often provided to sustain the high circumferential compressive stress developed. The cone/cylinder/skirt/ring junction, known as the transition, may fail by plastic collapse under the large circumferential compression. In this paper, an elastic-plastic large-deflection finite element analysis is employed to study the plastic collapse behavior of this junction. A typical structure is first examined to study the distribution of stresses, the effect of large deflections, the formation of a plastic collapse mechanism, and the collapse process. A simple theory proposed by Rotter, which is based on a reinterpretation of the classical limit analysis of ring-loaded cylinders, is next outlined and its background further clarified. An improved version of Rotter's equation, which applies to a wider range of geometries, is then proposed for use in design.