Silo quaking of iron ore train load out bin – a time-varying mass structural dynamic problem

Expanded flow bins are commonly used in the material handling industry to store and load train wagons. These bins are known in the industry as Train Load Out (TLO) bins. Several iron ore TLO bins have been designed and constructed to accommodate this demand. It has been reported that some iron ore TLO bins suffer a dynamic condition during discharge known as silo quaking. The quake causes several problems, which could lead to structural connections failure, reduced fatigue life of structural connections, computer data corruption, on-site personnel discomfort, loss of production, and increase in maintenance costs. However, the author had structurally designed a 2500 tonne iron ore TLO and prevented silo quaking by providing sufficient stiffness, damping and mass to counterbalance the pulsating loads and mass losses produced by the flowing iron ore. In this paper, a numerical model incorporating time-varying mass will be presented to explain the dynamics of Iron Ore TLO Bin. The model is validated by experimental results obtained from a 1 in 10 scaled model. The proposed numerical model supports the theory that pulsation loads occur in almost all bins and whether the induced dynamic loads cause any quaking problems are dependent on the severity of the loads, natural frequencies of the bin and its supporting structure.