PARAMETRIC STUDY ON THE MODELLING ASSUMPTIONS OF WOOD PALLET SLIDING

Although steel storage pallet racks seem like simple structures, their seismic evaluation is a difficult task. Their seismic response is characterized by flexible floor diaphragms and rather different response periods on their principal orthogonal directions (i.e., rigid in the cross-aisle direction and flexible in the down-aisle direction). There could be significant mass irregularities due to load and unload pallet processes, and typically, the mass sources (i.e., goods in wood pallets) are not attached to the steel frame. This characteristic can lead to the sliding of the pallets with diverse effects on the overall seismic response. On one hand, the sliding items can hit the steel frame with deleterious results or can lead to the fall of the pallets with damage to the stored items. On the other hand, sliding behavior reduces the total seismic mass as it detaches from the structure and also produces an additional energy dissipation through the friction between the pallet and the steel frame. This parametric study evaluates the sensitivity of the modeling assumptions of the sliding behavior of wood pallets, such as total weight, friction coefficient, seismic intensity, and sliding initial stiffness. The results show that the modeling assumption can significantly influence the sliding response, especially that of the sliding initial stiffness.