Compression tests of fixed-ended and pin-ended cold-formed plain channels

Abstract

The report describes a test program on cold-formed plain channel columns compressed between fixed ends and pinned ends. It is shown that local buckling does not induce overall bending of fixed-ended channel columns, as it does of pin-ended channel columns. A series of tests was performed on plain channel specimens consisting of two cross-section geometries fabricated from high strength steel by brake-pressing. Tests were performed over a range of lengths which involved pure local buckling, overall flexural buckling and flexural-torsional buckling. The local buckling loads obtained from testing are shown to be in excellent agreement with theoretically determined local buckling loads. The different effects of local buckling on the behaviour of fixed-ended and pin-ended channels are investigated by comparing strengths, load-shortening, load-deflection, load-end-rotation and load-end-moment curves, as well as longitudinal profiles of buckling deformations. Detailed measurements of geometric imperfections and material properties were conducted.