Flange Local Buckling Resistance and Local–Global Buckling Interaction in Slender-Flange Welded I-Section Beams

AISC Specification Chapter F characterizes the flange local buckling (FLB) strength of I-section members having a slender compression flange as the theoretical elastic plate local buckling resistance, ignoring beneficial local post-buckling strength. Previous research has shown that this results in highly conservative strength predictions for slender-flange members. Additionally, potential interaction between local and global lateral-torsional buckling modes is not considered in the AISC Specification. These aspects can be important in applications involving the use of slender-flange members. This paper investigates a number of potential methodologies to account for local post-buckling strength as well as local–global buckling interaction in beams having slender flanges. A parametric finite element analysis (FEA) study is conducted considering a range of I-section members. The strength predictions from the proposed methodologies and the AISC Specification are evaluated against the FEA results as well as against a database of measured strengths from previous experimental tests of I-section beams governed by FLB. Recommendations are provided focusing on simplicity of the calculations and the efficacy of their predictions.