Sway behaviour of high rise steel storage racks

Abstract

Storage racks are used throughout the world for bulk storage of materials. They are generally cold-formed steel structures and can be up to 40 metres in height. Collapse can have a high financial cost and has been relatively common when compared to conventional structures. This is believed to be due to a lack of understanding of rack behaviour. Lateral (down-aisle) stability of these structures is usually provided by the ability of the beam-to-column and base-plate connections to prevent down-aisle sway. The research in this thesis focuses on the beam-to-upright connection and its role in lateral frame stability. The main aim is to determine the best way to evaluate stiffness of this connection and to account for it in design. In order to do this, numerous tests have been performed. These tests include the standard tests currently employed to study joint behaviour: the portal sway test and the cantilever test. A modified version of the cantilever test is also developed and performed and compared with the standard tests. Full-scale testing of three storey frame sub-assemblages have been performed as well and use a complex rig to test the sub-assemblages as though they are the lower levels of a high rise rack. The ng allows both the loading and unloading in the post-ultimate range to be followed. Results from all of the various tests as well as comparison of the results are presented in the thesis, along with conclusions regarding the usefulness of each test in the evaluation of actual rack frame behaviour. The main conclusion is that the portal sway test provides much more accurate estimates of frame behaviour than the cantilever tests. The modified cantilever tests allow the actual full range behaviour of connections undergoing closing then opening to be better understood. A design example concludes the thesis and demonstrates the accuracy of designs based on the different test methods.