ABSTRACT
Cold-formed steel haunched portal frames are popular structures in industrial and housing applications. They are mostly used as sheds, garages, and shelters, and are common in rural areas. Cold-formed steel portal frames with spans of up to 30 m (100 ft) are now being constructed in Australia. As these large structures are fairly new to the market, there is limited data on their feasibility and design recommendations. An experimental program was carried out on a series of portal frame systems composed of back-to-back channels for the columns, rafters, and knees. The system consisted of three frames connected in parallel with purlins to simulate a free standing structure, with a span of 14 m and apex height of 6.8 m. Deflections were recorded at various locations to measure global and local movement of the structural members. Several configurations were tested including variations in the knee connection and loading of either vertical or combined horizontal and vertical loads. Finite element models of the tested frames were completed. They were calibrated with material properties from coupon tests and column base stiffness data obtained from component tests. The models were validated with the experimental results, thus confirming the suitability of the developed modeling technique to accurately capture frame ultimate capacity and deflections. Additionally, parametric studies were completed through FEM to determine the effect of various knee connections, as well as the effect of column base stiffness on frame capacity and behavior for various loading conditions. Design recommendations based on the work herein are presented.
