Buckling behavior and design of large-size and high-strength steel angle under combined compression and biaxial bending

This paper aims to investigate the behavior of large-size and high-strength steel angle (LHS) components under combined biaxial bending and axial compression. A theoretical analysis for angle sections subjected to combined action and the plastic development coefficient calculation method was performed. The behavior of 28 Q420 LHS beam-column components was tested, and the finite element model was developed and validated against the test result. The comprehensive parametric study was adopted to perform LHS beam-column components with different material grades, cross section sizes, slenderness ratios and loading eccentricities. Numerical results obtained from the parametric study were compared with the current design codes to provide accurate prediction of design strength. The research findings indicate that the angle section's elastic design approach is rather conservative, possessing a degree of plastic reserve. The eccentricity can alter the LHS beam-column components' failure mode, and the critical eccentricity characteristic becomes less apparent as the biaxial eccentricity increases. The proposed modified design formula for LHS components under combined action, can achieve reliable and accurate design predictions.