Stability Considerations of Unequal-Leg Angle Stainless Steel Columns

Due to limited research, design guidelines for stainless steel single-angle compression members in the pending AISC 370: Specification for Structural Stainless Steel are currently limited to equal-leg sections and require the consideration of flexural-torsional stability in contrast to the previous Design Guide 27 recommendations. This paper reports on the ongoing experimental and numerical investigation on the stability considerations of unequal-leg angle stainless steel columns. A series of unequal-leg angles with cross-sectional dimensions of 3"" x 2"" x ¼"" and lengths ranging from 10 to 148 inches were tested in compression. From these tests the ultimate loads, displacements, twists, and failure modes were recorded through the use of strain gauges and an optical tracking system. The material properties were obtained through a series of tensile coupon tests, and the residual stress distributions were measured by the sectioning method. In addition, the member geometric imperfections were measured through a non-contact 3D laser scanning technique. The data obtained from these tests was used to validate a finite element model of the unequal-leg angles. A parametric study was carried out with the validated model to obtain numerical capacities and failure modes for various geometrical parameters. The results obtained from this ongoing investigation will serve to inform design requirements for unequal-leg angles in compression including evaluating the requirement to consider flexural-torsional stability.

Learning Objectives:
Describe the behavior and failure modes of unequal-leg angle stainless steel compression members.

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