The Effect of Structural Stiffness on Iron Ore Train Load Out Bin

Abstract

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. Australia has experienced a surge in commodity demand, especially iron ore, due to the undergoing industrialisation in China. Several iron ore TLO bins have been designed and constructed to accommodate this demand. It has been reported that a number of 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. In this paper, an analysis and design of an iron ore TLO bin will be presented. The bin has the capacity of 2500 tonnes and an average discharge rate of 11000 tonnes per hour approximately. The bin has been built and commissioned for use in 2010, and no quaking problem has been encountered since. Based on design experiences, it is found that the frequencies of silo quake in TLO bins are generally less than 2 Hz and can be damped out by modifying the stiffness of the supporting structure as a whole. It is therefore proposed that there exists Silo Vibration Spectra similar to that of Earthquake spectra and also there are discreet zones within the Silo Vibration Spectra where the fundamental natural frequencies of TLO bins can be parked to minimise the effect of silo quake.