Design aspects of cold‐formed steel portal frame connections

This paper discusses recent advances in knowledge related to the behaviour and capacity of cold-formed steel portal frame connections. The focus is on how to implement the findings of the latest experimental, numerical and analytical studies into the design standards, particularly the Eurocodes.

A number of issues demand priority: 1. Cold-formed steel frame connections commonly fail by cross-sectional instability near the first bolt line, as a result of a shear lag effect originating from the fact that not all plate elements in the cross-section are connected to the central bracket. This shear lag effect exists in compression as well as bending; 2. Portal frame members are typically subject to a combination of bending, shear and axial force, and appropriate interaction equations are needed for connection design; 3. The rotational stiffness of the eaves and apex connections are of paramount importance: these connections typically act semi-rigidly and affect the moment distribution in the frame, as well as deflections. Component models are proposed which account for some of the specific configurations used in practice and can be used to accurately predict moment-rotation behaviour.