Lateral load behavior of shear connections between steel storage racks and the spine bracing with posts

High-rise steel storage racks are cold-formed thin-walled steel frames, which achieve their lateral strength and stiffness by the use of a spine bracing system in the down-aisle direction commonly located at a short horizontal distance away from the main rack frames. The shear connections between the main rack frame and the spine bracing system play a dominant role in the effectiveness of the spine bracing system. This paper experimentally investigates the behavior of the shear connections used in industrial practice between a steel storage rack and the spine bracing system with posts using four groups of three nominally identical connection specimens. By employing a digital image correlation (DIC) system, the tests generate comprehensive data and establish the real-time deformation fields of individual components of such shear connections. Based on the component-based approach, a linear-elastic analytical model is developed for the type of shear connections under consideration. The proposed analytical model explicitly captures the behavior of the individual connection components, including the three-dimensional flexural bending of endplates, as well as the distortions of the open sections of the upright and the bracing post. Based on the proposed model, this paper quantifies the contribution of each component towards the total deformation of the shear connections. The investigation establishes that the cross-sectional distortion of the bracing post and the out-of-plane bending of the upright web are the most flexible components of such shear connections. Recommendations associated with the shear connections under consideration are proposed for the rack designers and manufacturers.