Tensile Resistance of Face-to-Face (F2F) Flange Connection of Cold-Formed Steel (CFS) Channel

Abstract Cold-formed steel (CFS) structures are becoming popular due to their lightweight, high strength, and less expensive. However, CFS structures are susceptible to connection failures, which is a major safety concern. Self-drilling screws are commonly used to connect CFS as a face-to-face (F2F) connection and there is lack of research investigation of their tensile performance with various connection types and testing variables previously. This study is conducted to investigate the tensile performance of CFS with F2F connection that screwed on both top and bottom flanges. The effects of CFS thickness and screw numbers on the tensile resistance and failure modes of the CFS connections were investigated. Mechanical properties of the CFS plate and M5.5 self-drilling screw were determined based on testing specified by ASTM E8 and ASTM F606 respectively, with the average yield tensile stress, f y , of CFS plate exceeded 500 N/mm 2 . A total of 12 samples of CFS connections were tested under tensile test, with two main parameters which were the thicknesses (0.75 mm and 1.0 mm), and the number of connected screws (2 and 4 units). From the laboratory finding, the tensile resistance of CFS connection increased with addition number of screws and/or thicker CFS plate up to two times due to its resistances against plate bearing and shearing forces of the fasteners. Besides, the bearing failures was occurred in most laboratory samples, and the screws snapped after passing the ultimate tensile load.