Vertical wall loads in a model grain bin with non-axial internal inserts

A study was conducted to estimate the degree of load asymmetry in a bin with non-axial internal inserts. Internal inserts in the form of an annulus segment were attached to the wall, and their influence on vertical wall loads during centric filling and discharge in a model bin were measured. Wall and floor loads were measured in a corrugated-wall model grain bin with a diameter of 2.44 m and a height of 7.3 m filled with soft red winter wheat to a depth of 6.7 m (height-to-diameter ratio of 2.75). Tests were conducted with inserts that extended circumferentially 30°, 60°, or 90° around the bin, having a width of 7.6, 15, or 23 cm and attached to the bin wall at height-to-diameter (H/D) ratios of 0.31, 0.62, or 0.95. These inserts represented between 1% and 8.6% of the bin floor area. The results showed that with centric filling, considerable asymmetry of static wall loads occurred. The asymmetric loading was caused by the horizontal component of the velocity of the grain stream filling the bin, produced by the drag conveyor. This loading created wall moments in the bin of approximately 3 kN-m. The wall moments generated by imperfect centric filling varied depending on the angular position of the inserts. For a 23 cm wide, 90° insert, which was the worst observed situation, the wall moment was approximately 5 kN-m. The onset of symmetric discharge resulted in an increase in vertical wall load and a decrease in the wall moment. A change in flow pattern from mass flow to funnel flow, as well as the influence of the insert, was clearly shown by the change in wall moment with discharge time.