Local and Distortional Biaxial Bending Capacities of Cold-Formed Steel Storage Rack Uprights

Abstract

Rack-supported buildings, also referred to as "clad racks", are currently gaining popularity in the logistic industry. The storage rack, usually manufactured from cold-formed steel members, supports both the building enclosure and the stored goods. Due to the combined action of the wind loading and stored pallets, uprights undergo biaxial bending. Internationally, the design of the uprights is performed in accordance to the provisions in the North American Specification (AISI S100:2012), Australian and New-Zeeland standard AS/NZS 4600 (2005) or Eurocode 3 (EN 1993-1-3, 2006) for design of cold-formed steel structures. In these Specifications, a linear interaction equation is used to account for members subject to biaxial bending and may be inaccurate. In order to produce safe and economical design guidelines, the actual interactive relationship between bending about the major and minor axes, for local and distortional buckling, is experimentally investigated in this study for two types of storage rack uprights. Results on perforated and non-perforated uprights are presented and discussed in this paper. Results show that a nonlinear interactive relationship governs the biaxial bending of the studied uprights. This relationship is discussed in some details and compared to the linear equation proposed by the international Specifications. Future studies are also discussed.