TESTS OF FIXED-ENDED PLAIN CHANNEL COLUMNS

The paper describes a test program on cold-formed plain channel column s compressed between fixed ends and pinned ends. Whereas it is well-kn own that local buckling of pin-ended channel columns induces overall b ending, this phenomenon does not occur in fixed-ended channel columns that remain straight after local buckling and only bend when overall b uckling occurs. These fundamentally different effects of local bucklin g on the behavior of pin-ended and fixed-ended channel sections lead t o inconsistencies in traditional design approaches, which account for full or partial rotational end restraint solely by using effective len gths. A series of tests was performed for different geometries of cros s section fabricated by brake pressing from high-strength steel sheet. Tests were performed over a range of lengths such that the column cur ve could be obtained. Local buckling loads were also obtained from the fixed-ended column tests. Detailed measurements of local and overall geometric imperfections, material properties, and residual stresses we re conducted. The purpose of this paper is first to present and compar e the test strengths with existing Australian/Mew Zealand, American, a nd European specifications for cold-formed steel structures and, secon d, to propose recommendations for the design of fixed-ended singly sym metric columns.