Drive-in steel storage racks II: Reliability-based design for forklift truck impact

Abstract

Steel drive-in racks are susceptible to structural failure due to accidental impact by operating forklift trucks. Under impact, the upright bends and the supported pallets may drop through the rack to cause structural collapse if the bay opening exceeds the pallet bearing width. This drop-through limit state has not been considered in the existing rack design standards. This paper proposes a simple equation to calculate the equivalent static impact force based on recent tests and nonlinear dynamic analysis of drive-in steel racks. An impact load factor is developed on the basis of a structural reliability assessment, taking into account the uncertain nature of the impact force, structural resistance and models used in structural analysis. In design practice, the bay opening is determined from factored impact loads, and is not to exceed specified limits.