Evaluation of lateral-distortional buckling strength of castellated steel beams using regression models

Abstract

The effects of web distortion on the buckling behavior of castellated steel beams have rarely been studied; and so far, no exact formula has been proposed to predict the lateral-distortional buckling (LDB) capacity of such beams. Therefore, in the following paper, an attempt has been made to propose new formulas for predicting the LDB capacity of castellated beams using two regression models. To do this, at the first, an extensive parametric study including 480 finite element (FE) models was performed. Both material nonlinearities and initial geometric imperfections were carefully applied to the models and they were also well validated against experimental results. The next, based on the parametric study, nine non-dimensional parameters that affect the LDB behavior of castellated beams were considered, and using them as input parameters, two predictive models including stepwise regression (SR) and multiple regression (MR) were developed. The models were then used to provide new formulations for estimating the LDB strength of castellated steel beams. In the end, the proposed formulas were compared with the existing design guides available for estimating the buckling strength in AS4100, EC3, and AISC codes. The results showed that the proposed formulas for use by practical engineers are accurate enough.