Compressive Strength of Advanced High Strength Cold-Formed Steel Members with Compression Warping Restraint only

Abstract

This work aims to investigate the compressive strength of cold-formed steel members made from Advanced High strength Steel (AHSS) sheets. An experimental investigation has been conducted with 156 pure compression tests on unbraced AHSS columns. Four parameters are varied in the testing: nominal yield stress (340 MPa to 1200MPa), member length (305 mm to 1219 mm), cross-section types (C and Sigma), and section depth (102 mm and 152 mm). The failure behavior of the longer unbraced length columns with higher strength steel are observed to exhibit buckling mode interactions. The peak loads from the tests are compared to the strength predictions by the Direct Strength Method (DSM) implemented in AISI S100 and AS/NZS 4600. It is found that the current DSM cannot conservatively predict the compressive strength of the longer unbraced AHSS columns tested in this study. Design methods proposed in the literature in addition to careful consideration of the test boundary conditions are explored to recommend extensions to the current DSM to address the observed behavio