Influence of plasticity on lateral–torsional buckling behaviour of cellular beams

Abstract

The use of steel beams with large circular web openings along the length of the beam has increased steadily during the last decades. However, not all aspects of the design of these cellular beams have been studied extensively, such as lateral–torsional buckling (LTB). In previous work, an existing design rule for this failure mode was investigated for purely elastic beams. Even though this rule was shown to be quite accurate for most cases, it could sometimes give unsafe results for certain short length geometries. In reality, however, the steel will display elastic–plastic behaviour, causing these geometries to fail by plasticity of the cross‐section rather than elastic instability. In this work, the design rule will be further examined by performing numerical simulations, taking into account these effects of plasticity, as well as imperfections and geometric nonlinearity. It will be shown that the existing design rule always gives safe results for the examined geometries.

Keywords:

• Cellular beams
• Lateral–torsional buckling
• Failure load
• Numerical simulations
• Abaqus