Evaluation of Critical Loads of Steel Frames using Iterative Buckling Analysis

This paper proposes a new method of inelastic buckling analysis to determine the critical load of steel frames. The inelastic analysis includes a modified bifurcation stability using the tangent modulus theory and a column strength curve. The inelastic buckling analysis can consider geometric imperfections or residual stresses in a steel frame by using the column strength curve. Criteria for inelastic buckling analysis are suggested in order to account for the effect of the primary moment as well as the axial force of members by using beam-column interaction equations. Conventional elastic buckling analysis and refined plastic hinge analysis were carried out to validate the proposed inelastic buckling analysis for simple columns with geometric imperfections and a four-story plane frame.