Predicted patterns of filling pressures in thin-walled square silos

In this paper, a validated finite element model for silo filling pressures in square vertical walled metal silos is used to generate new information in pursuit of the development of design rules. The computational model predicts the state of stress in the stored solid and the pressures imposed on the silo walls. The non-uniform horizontal pressure distribution at any given depth at the end of filling in a silo with flexible walls is predicted well. Results from the model show that the hyperbolic function proposed for this horizontal pressure distribution, previously developed from test results, gives a close representation of the new predictions. The coefficients of this function are found to vary with depth, and to depend on the relative stiffness of the stored solid and the silo wall. The results thus demonstrate the role of the stiffness of a stored solid in determining wall pressures in flexible-walled rectangular silos. The paper identifies the key parameters that control the extent of non-uniformity in the horizontal distribution of wall pressures and shows the relationships for stored sand, gravel and wheat.