Effect of reduced joint strength and semi-rigid joints on cold-formed steel portal frames

Jackson, Colin and Wrzesien, Andrzej and Johnston, Ross P. and Uzzaman, Asraf and Lim, James (2012) Effect of reduced joint strength and semi-rigid joints on cold-formed steel portal frames. In: 6th International Conference on Coupled Instabilities in Metal Structures, CIMS 2012, 2012-12-03 - 2012-12-05.

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    Abstract

    This paper considers the effect of semi-rigid joints and finite connection length on the design of cold-formed steel portal frames sized using a rigid joint and full joint strength assumption, and whether it can offset the fact that the joints cannot sustain the full moment capacity of the sections. The paper shows that for frames of modest span (around 10 m), sized using a rigid joint and full joint strength assumption, that the frames are unsafe under gravity load and do not satisfy the ultimate limit state. Designers should therefore take the semi-rigidity and partial strength of the joints when analysing such frames, particularly when stressed skin action is also used in the design.