Experiments on a Full-scale Coal Hopper

In this paper, measurements taken on the conical hopper of a full-scale 3000 tonne coal bin are described and compared with theoretical considerations. The measurements consist of strains at twenty four locations of the hopper, and reveal several aspects which may not be obvious to the designer. It is clear from the experimental data that the distribution of normal and friction stress in the hopper, as evidenced from circumferential and meridional strain readings on the outer surface, is far from uniform. The non-uniformity in applied pressure need not be pronounced for strong fluctuations to appear on the steel surface. These are caused by combinations of membrane and bending stresses in the two principal directions. It is found that a 13 per cent fluctuation in applied pressures, varying in a sinusoidal manner around the circumference, creates fluctuations in surface strain of the order of 80%. Implications of these variations for the fatigue life of these structures are examined.