Experimental Investigation of Dimpled Screw Connections in Thin‐Walled Cold‐Formed Steel Sheets

Abstract

Cold‐formed steel (CFS) structures are increasingly adopted in modular construction due to their efficiency and adaptability. Screw connections in thin‐walled steel sheets often exhibit localized bearing deformation, reduced stiffness, and limited ductility, which can govern structural performance. An effective method to mitigate these limitations is the use of dimples, i.e., local indentations around screw holes that improve stress distribution, restrain out‐of‐plane deformation, and delay critical failure mechanisms. Current design standards, including Eurocode 3 and AISI S100, do not provide analytical models for such modified connections and therefore rely on experimental verification. This paper presents an experimental investigation of single‐shear screw connections in thin‐walled steel sheets reinforced with dimples. The study evaluates load‐bearing capacity, elastic stiffness, deformation response, and failure modes under shear loading, focusing on the combined influence of dimples and sheet thickness. The results show that dimples significantly enhance mechanical performance by increasing strength and stiffness, delaying bearing failure, and promoting stable, ductile behaviour, thereby supporting their future consideration in the design of cold‐formed steel connections.