A Microscopic Theory for Predicting Loads in Storage Bins for Granular Materials

Abstract

A two-dimensional model for predicting loads in granular material storage bins was developed from the micromechanics approach, in which force equilibrium is considered at the particle (microscopic) level. The significance of this approach is to allow some particle property parameters to be used in calculations of stresses in storage bins for granular materials. Three key assumptions are made in the model: (1) the granular medium has a hexagonal structure consisting of elastic spheres, (2) rotation and slip of particles are negligible, and (3) stresses are uniform across the bin cross-section. Predictions by the proposed model are in close agreement with the experimental data reported by three different groups of researchers for maize and wheat storage bins. Janssen's equation, recommended by most design standards and codes, has been shown to be a special case of the present theory. The traditional assumption of constant lateral to vertical stress ratio was found to be valid only for frictionless walls or rigid particles.