New predictive equations for lateral-distortional buckling capacity assessment of cellular steel beams

Abstract

Assessment of the ultimate capacity of the cellular steel beams subjected to the lateral-torsional buckling containing web distortion (lateral-distortional buckling) was rarely investigated. So far, there is no accurate formula to predict the lateral-distortional buckling (LDB) capacity of such members. Here, extensive simulations (660 specimens) based on the nonlinear finite element analysis (FEA) were carried out to simulate the cellular steel beams in distortional-buckling mode. The influence of eight parameters that may affect the LDB capacity was deeply investigated. Then, gene expression programming (GEP) and nonlinear multiple regression (NMR) algorithms progressed as predictive models to obtain formulae for measuring the failure moment capacity of the cellular steel beams. The used data for the GEP and NMR models development, obtained from the FEM simulations that were done initially. It was attempted to derive exact enough formulae, which considers all the variables that may affect the LDB capacity of cellular steel beams. The validation of the GEP and NMR models have been further verified by several statistical criteria. Finally, a comparison was performed between the proposed formulae and the predictions obtained from AS4100, EC3, and AISC codes. It was shown that the proposed formulae are enough exact and applicable to use by practicing engineers.