Torsional Brace Strength Requirements for Steel I-Girders

Torsional bracing is often used to stabilize beams in building and bridge applications. The bracing improves the stability by restraining twist of the cross section. Adequate stability bracing must satisfy both stiffness and strength requirements. The torsional brace strength requirements in the latest edition of the AISC specification (2016) was significantly changed from previous editions of the specification (2010). This paper outlines a parametric study on the strength requirements of beam torsional bracing. The paper demonstrates that the latest expression results in brace strength predictions that can be significantly unconservative. The paper recommends returning the strength provisions that were provided in previous editions of the specification.

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