Cold-formed steel portal frames are an increasingly popular structure in the housing and industrial sectors, and are commonly used for garages, sheds, and shelters. Longer span cold-formed steel portal frames are relatively new to the market, and as a result limited design guidance and recommendations exist, including the strength and stiffness of the connections. The apex connection stiffness affects the distribution of internal actions and deflections of a portal frame, and therefore, it is necessary to quantify the apex stiffness for use in design models to accurately determine the frame behavior. An experimental program was carried out on a series of twelve apex connections of portal frames composed of back-to-back lipped channels for the rafters and back-to-back lipped L apex brackets, which were connected by bolts through the webs. The channels had a depth of either 200 or 150 millimeters, and thickness of 1.5, 1.9, or 2.4 millimeters. The apex brackets were 2.4 millimeters thick, and the dimensions varied to match with the connecting rafter sections. The apex connection stiffness and strength were quantified, and the effects of rafter thickness and depth on the connection stiffness and strength were determined. The aim of this work is to quantify the apex connection stiffness of cold-formed steel portal frames composed of back-to-back channels and L-brackets to enable practicing engineers to accurately determine the internal actions and deflections of portal frames.
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