Study on the Inelastic Buckling Strength of Stepped I-Beams Located at Midspan Subjected to Pure Bending

Lateral Torsional Buckling Strength of Stepped Beams at Midspan have already been incorporated in the structural design codes. The existing equations are based only on the elastic theory for doubly-symmetric sections and gives rough approximation. In addition, previous researches using inelastic analysis were only conducted for stepped beams at the end of supports; inelastic analysis of stepped beams at midspan has not yet been considered. The aim of the study is to investigate and develop a general formulation of the inelastic lateral-torsional buckling strength equation of doubly symmetric stepped I-beam located at midspan. A universal finite element analysis program, ABAQUS, and a regression program, MINITAB17, was used in order to derive equation for the buckling capacity of the stepped beams. The results were compared to the proposed equation by the previous research for singly stepped beams and showed better results with lesser unconservative estimates. Improvements and further study can be made which can include experimental test to verify the results.