Post‐Buckling Instability of Steel Beam‐Columns

Abstract

This paper describes an investigation of buckling and post‐buckling behavior of steel beam‐columns. Beam‐columns having a H‐shaped cross section were studied for their deformability as well as ultimate strength. A constant axial thrust and monotonically increasing end moments were applied to the beam‐columns. Both experimental and analytical investigations were made in the study. Variables in the experimental study were cross‐sectional shape, length, and intensity of axial force. Numerical analysis demonstrated its capability to properly simulate the behavior of the tested beam‐columns. On the basis of parametric study using the numerical analysis, important findings can be drawn. First, lateral torsional deflection is more distinguished for beam‐columns with less axial force. Second, beam‐columns having a small slenderness ratio do not lead to instability by lateral torsional buckling, indicating a stable plastic range. Third, deformability drastically decreases once the slenderness ratio exceeds a certain level. Available formulas which estimate the ultimate strength of beam‐columns, in addition, are found to be effective.