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

摘要

The use of steel beams with large circular web openings along the length of the beam hasnincreased steadily during the last decades. However, not all aspects of the design of thesencellular beams have been studied extensively, such as lateral–torsional buckling (LTB). Innprevious work, an existing design rule for this failure mode was investigated for purely elasticnbeams. Even though this rule was shown to be quite accurate for most cases, it could sometimesngive unsafe results for certain short length geometries. In reality, however, the steel will displaynelastic–plastic behaviour, causing these geometries to fail by plasticity of the cross-section rathernthan elastic instability. In this work, the design rule will be further examined by performingnnumerical simulations, taking into account these effects of plasticity, as well as imperfections andngeometric nonlinearity. It will be shown that the existing design rule always gives safe results fornthe examined geometries.