Lateral Torsional Buckling Effect on I- Section With Flange Bracing as Per IS 800:2007

Abstract

The lateral-torsional buckling occurs in a beam when the beam's unsupported length is greater. The beam will fail by lateral-torsional buckling when the compression flange is free to rotate and displace laterally. The lateral stability of the I-section is an important factor in the design of pre-engineered buildings. The design to resist the bending and twisting in the frame I-section that is rafter and column in lateral direction flange bracing acts as a restraint to resist lateral-torsional buckling. The top flange is connected with purlins to act as a lateral restraint. The bottom flange torsional moment is resisted by flange bracing. Increasing the flange bracing decreases the unsupported length of the compression flange, so there is a decrease in lateral-torsional buckling. If the non-dimensional slenderness ratio ( λlt < 0.4 ) the section is said to be laterally supported, according to IS 800. In this paper, how the lateral-torsional buckling affects when the restraints are provided at different intervals and how the section will be affected when the flange width, thickness, web depth and thickness changes.