A Novel Methodology for Determining the Initial Stiffness of Speed‐Lock Beam‐to‐Upright Connections Based on Stiffness Evolution Analysis

Abstract Ensuring the safety and stability of steel storage racks depends on properly sizing components and connections, typically based on mechanical properties determined through testing. The overall performance of these systems, especially stiffness and load distribution, is highly influenced by the mechanical behaviour of speed‐lock beam‐to‐upright connections. Two key parameters—design moment and stiffness—are significantly affected by initial stiffness. Accurately predicting initial stiffness is vital for aligning design with real‐world performance. This paper presents a new method for calculating initial stiffness, focusing on its evolution through upright‐connector interactions. Stiffness evolution is defined as the moment‐rotation curve over time. The proposed Stiffness Evolution Method was applied to six setups combining three uprights and three beams with a shared connector. Experimental tests followed the EN15512 cantilever method. Variations in moment‐rotation curves prompted further analysis of internal contacts via testing and modelling. Findings showed key contact points at the lateral connector‐to‐upright area and first two tab‐slot interactions. Compared to existing methods, the new approach yielded lower standard deviations and more reliable stiffness predictions.