Experimental investigation of fixed-ended hot-rolled austenitic stainless-steel unequal-leg angles under compression

Abstract

Structural stainless steel is gaining traction in the structural engineering field, however, there is currently limited published data on the performance of stainless steel unequal-leg single-angle compression members. This limitation of published data is reflected in the recently released AISC 370: Specification for Structural Stainless Steel Buildings which is limited in scope to equal-leg cross sections. Furthermore, the Specification requires the consideration of flexural–torsional buckling for single angles which is in contrast to the original design guidelines from AISC published in 2013, which mirrored the carbon steel specifications and did not required checking for flexural–torsional buckling for single angles. This paper reports a comprehensive experimental study on the behavior of hot-rolled austenitic stainless steel unequal-leg angle columns. A series of unequal-leg angles with cross-sectional dimensions of 76.2 × 50.8 × 6.35 mm (3″× 2″× 1/4″) and lengths ranging from 250 mm (10″) to 3760 mm (148″) were tested in compression. The ultimate loads were recorded in addition to displacements, twists, and failure modes 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 member geometric imperfections were measured through a non-contact 3D laser scanning technique. In addition, residual stress distributions were measured by the sectioning method. The results obtained from this experimental investigation indicated: (1) that torsional buckling is dominant in the shorter lengths and minor-axis flexural buckling in the longer lengths, with a transition occurring gradually in the middle lengths; (2) that the measured material properties are significantly higher than nominal values, and that this had a significant effect on the capacity predicted by the design provisions; (3) flexural buckling design provisions provide a better estimation than flexural–torsional buckling design provisions, although both are conservative.