Finite element modelling of castellated steel beams under lateral-distortional buckling mode

Abstract

This paper examined the effects of web distortion on the buckling behavior of castellated steel beams. To this purpose, a series of nonlinear finite element (FE) models was constructed and well verified against an experimental work on the distortional buckling of castellated beams; both material nonlinearities and initial geometric imperfections were carefully applied to the models. Next, an extensive parametric study was performed using the finite element models to investigate the effects of beam length, steel grade and cross-section dimensions on the ultimate buckling load and buckling modes of castellated steel beams. The results showed that the use of low grade steel and thick flanges makes an economical design in the castellated steel beams. Moreover, it is concluded that lateral-distortional buckling (LDB) mode is more common in the castellated beams with intermediated overall slenderness, thick flanges and slender web. Finally, the ultimate loads obtained from finite element analysis (FEA) were compared with the results predicted by AS4100, EC3 and AISC codes. It was concluded that all three Specifications provide unsafe estimates for most specimens in this study.