Cold-formed steel sections are commonly used as construction members for various applications. These sections have slender, thin-walled open cross-sections, which make them highly susceptible to instability phenomena, including local, distortional, and global buckling (flexural or flexural-torsional buckling). Most of the existing literature assumes that cold-formed steel members experience either uniform compression or uniform bending and derives the elastic buckling loads corresponding to these specific buckling modes. However, in actual joints within steel-framed structures, cold-formed steel members experience nonuniform stresses owing to the simultaneous action of compression and bending caused by eccentricity. Current design codes incorporate simple design formulae that assume a linear summation based on the compression-to-bending stress ratio. However, these design formulae do not provide a rigorous evaluation of the buckling load. Therefore, we conducted stub column tests under eccentricity and performed analyses in this study using the finite element method. The results confirmed that the influence of the eccentricity led to a buckling mode that differed from that of the uniform stress state. Additionally, the ultimate load and the load-displacement relationship underwent significant changes owing to the influence of the eccentricity. Furthermore, we derived the elastic buckling load of each buckling mode changing with the amount of eccentricity using the energy method and clarified the influence of eccentricity on the buckling mode and the change in buckling load.
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