Fatigue Design Of Cold‐Formed Thin‐Walled Z‐Rails Subjected To Concentrated Load

Cold‐formed thin‐walled steel members are extensively used in rack storage structures due to their advantageous geometrical and mechanical properties for a minimum weight. In automatic multi‐deep rack systems, shuttles are used to bring pallets to their final storage position; these shuttles are usually circulating on elements made of Z sections, which facilitates their movements and ensuring a sufficient bearing and stiffness capacity. Due to the multiple passages of the shuttles, fatigue problems could occurred on these profiles, but this issue is not fully covered by the existing European normative document EN1993‐1‐9. This paper presents part of the results of a large experimental fatigue test campaign, in which 34 members made of thin‐walled cold formed steel Z sections have been tested, in order to characterize the fatigue resistance of two details as a part of the Z‐rail. The main objective of these tests was to derive the S‐N curve associated to both studied details. As a result, design provisions to assess the fatigue resistance of Z‐rails subjected to fatigue load are proposed for the practitioners, referring to the recommendations of prEN1993‐1‐9.