ABSTRACT
ABSTRACT: This paper describes a series of compression tests performed on welded H-section and channel section columns fabricated from mild steel plate of thickness of 0.6 mm with nominal yield stress 240 MPa. The ultimate strength and performance of the compression members undergoing the nonlinear interaction between local and overall buckling were investigated experimentally and theoretically. The compression tests indicated that the interaction between local and overall buckling had a significant negative effect on the ultimate strength of the thin-walled welded steel section columns. The direct strength method, which was newly developed and adopted as an alternative to the effective width method for the design of cold-formed steel sections recently by NAS(AISI, 2004), was calibrated for the application to the welded steel sections by the test results. The paper proves that the direct strength method can predict properly the ultimate strength of the welded section columns when the local buckling and flexural buckling will occur simultaneously or nearly simultaneously.
