Experimental and theoretical investigation of beam-to-upright subassemblies for HBSSR against progressive collapse

Abstract

This paper presents an experimental and theoretical investigation into beam-to-upright subassemblies in the high-rise braced steel storage racks (HBSSR) during a progressive collapse. A total of five double-half-span subassemblies were tested under a middle-column-removal scenario, involving various pallet loads, beam spans, connection types and bolt numbers. Three main failure modes, including tab cracking, bolt bearing and beam end failure and their combination, were observed in the tests. The development of the collapse-resisting mechanisms in the subassemblies are analyzed. Both flexural action and catenary action contribute to the collapse resistance of the subassemblies, with catenary action dominating ultimate resistance. The effects of critical geometric parameters on the collapse-resisting performance are also investigated. The ductility of the subassembly is improved when the beam span increases and the pallet loads exist. For Tab + Bolt (TB) connections, increased bolt number leads to increase of ultimate resistance and to decrease of ductility. For purely-bolted (PB) connections, increased bolt number impairs both ultimate resistance and ductility. Therefore, compared with the PB connections, the TB connections are preferable due to their better ductility in the collapse-resisting design. Moreover, a theoretical model based on the Component Method is developed to characterize the full-range load-displacement behaviour of beam-to-upright subassemblies. Validated against test results, the proposed model shows proper predictions of load-displacement curve and failure phenomenon.