Flexural Strength Prediction for Cold-Formed Steel Sections Unsymmetric About the Axis of Bending

The Direct Strength Method (DSM) is useful in determining the local and distortional buckling strength of cold-formed steel compression members and flexural members. This method provides a consistent approach applicable to any cross-section based on its yielding and elastic buckling characteristics. Recent research has shown opportunity for improvement for flexural members unsymmetric about the axis of bending. This paper investigates how additional stress redistribution due to asymmetry impacts strength. Adjustments to the DSM strength equations for local and distortional buckling are proposed to account for this behavior, and are validated against a wide variety of test and simulation results. A new form of the DSM strength equations is also developed to additionally address cases where section instability results in a reduced effective depth and therefore lower strength. This new proposed form offers simplicity and broader applicability suitable for consideration in design specifications.

Learning Objectives:
Some flexural members cannot maintain a stable section depth due to local or distortional instabilities, resulting in reduced strength.

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