The Analysis of Steel Bins Subject to Eccentric Discharge

Eccentric discharge is known to be a cause of dramatic and catastrophic failures in steel bins of circular planform. Most existing studies of the structural consequences of eccentric discharge assume that the two-dimensional curved shell wall may be represented by a one-dimensional ring and concentrate on the development of circumferential bending moments in the wall of the bin. This simplification of the structural form has led to a serious misunderstanding of the load-carrying mechanism in steel bins. Although circumferential bending accounts for some benign 'denting' failures, it cannot explain the catastrophic buckling failures often seen in eccentrically discharged steel bins. This paper demonstrates the real load-carrying mechanism of thin steel bins subject to eccentric discharge, and shows why catastrophic buckling failures are to be expected. A careful analysis is given of the pressures exerted on the bin wall by the flowing and static stored solids. These pressures are then used in a finite element analysis of the bin shell, and the patterns of stress developing in the wall are illustrated. Finally appropriate criteria are given to identify when buckling failures may be expected.