Flexural-Torsional Buckling Analysis of Steel Beam with Reduced Flanges

Flexural-torsional buckling of the beam in steel frame with reduced beam section (RBS) connections is analyzed. Base on the analysis of flexural-torsional buckling of the RBS beam under different loads using energy method, the critical moment calculation formula of ordinary beam is modified, and the critical moment calculation formula of RBS beam is presented. Moreover law of the RBS beam critical moment varying with cut sizes and location is discussed when compared to the critical moment of the uniform beam. The results show that: reduction has great effect on flexural-torsional buckling of RBS beam, critical moment of the RBS beam obviously decreases as compared with ordinary uniform beam, but single cut parameter has small effect on changes in critical moment; the effect of reduction on beam stiffness decreases as beam span increases.