Finite Element modelling of steel drive-in rack structures (No. R901)

Abstract

Steel storage racks, principally made from cold-formed steel profiles, are freestanding structures and designed to carrying heavy loads. Yet the amount of material used in their fabrication is minimised in structural design and racking companies often rely on 3-Dimensional second-order Finite Element Analysis to design storage racks as economically as possible. The FEA often includes non-linear material and/or connection stiffness. As storage racks are complex and slender structures, whose behaviour is influenced by the base plate to floor connection and by the pallet beam to upright connection (Baldassino and Bemuzzi (2000)), building accurate FG models is challenging. This report presents a Finite Element model of an unloaded and loaded drive-in rack structure. Contrary to the main type of racking system, referred to as ”selective rack”, where racks are one pallet deep and separated by aisles allowing each pallet to be always accessible, “drive-in” racks are typically 3 to 7 pallets deep and store pallets one after the other, with no space between them, on the “first-in last-out” principle. By optimising floor allocation, drive-in racks are often an attractive alternative to selective racks. The reported FE model is built using the commercial software Abaqus (2005) and numerical results are found to accurately reproduce experimental static test results performed on a full-scale drive-in rack (Ciilbert and Rasmussen (2009b)). The FE model is used to study the influence of the uplift of base plates on the global behaviour of the rack. Results show that the uplift of the base plate may significantly influence the overall displacement of the rack, and needs to be considered in design. Finally, the influence of pallets on the bending moment distribution in the uprights is analysed and reported herein.