Forces on monitoring cables during grain bin filling and emptying

Monitoring the temperature of stored grain with permanent cables suspended from the bin roof is common practice in commercial grain storage and is sometimes used in on-farm grain storage bins. Knowledge of the forces imparted on the cables by flowing grain is required for proper design of cables, connection hardware, and bin roofs, but there is little data in the literature for full size bins. To determine forces on different cable sizes and configurations, five different cable designs were tested during filling and emptying of wheat and corn. Two concrete storage bins, 4.6-m diameter and 25-m maximum depth, were used with cables suspended from the center of the bin or suspended 0.6 m from the sidewall. The bottom ends of the cables were weighted, but were not fully restrained. Forces on the cables were monitored during filling and emptying of the bins. Forces during emptying usually exhibited slip-stick behavior. The greatest forces were during emptying, where forces were often double those during filling, with vertical forces up to 4.7 kN for the largest cable. Both peak and average forces for bin emptying were significantly larger than corresponding forces for bin filling. Results showed no effect of grain type (corn or wheat) while cable size had significant effects on peak and average force in most cases.