Reassesment of lateral torsional buckling in hot-holled I-beams

Abstract

Lateral torsional buckling (LTB) of I-beams is characterized by simultaneous lateral deflection and twist. In this paper the influence of destabilizing and neutral effects of loadings and the possibility of the occurrence of web distortion, which characterizes the lateral distortional buckling (LDB), is numerically investigated. Recent research has shown divergences between the standard procedures of the American Institute of Steel Construction, Australian Standards and Eurocode with LTB numerical results. In addition, some procedures have recently been proposed for correcting possible deviations between the results of numerical analysis and standard procedures. In order to investigate this situation, elastic stability and physical and geometrical nonlinear analyzes are performed, using GBTul and ABAQUS softwares, respectively. The numerical model is calibrated considering experimental tests. The beams are simply supported, with fork supports at the ends, and subject to neutral and destabilizing effects of loading. The beams are subject to uniform bending, mid-span concentrated load and uniformly distributed loads. The parametric study is performed by varying the geometric cross section parameters. The results are compared with international standards and analytical procedures. It is concluded that the influence of destabilizing and neutral effects of loadings is responsible for providing non-conservative results when compared to the American Institute of Steel Construction procedure. The occurrence of LDB in hot-holled I sections influences the lateral stability strength of I-beams, but it is not predominant. With the possibility of using the elastic critical moment obtained by the elastic stability analysis, the conservative situation of EC3 is verified. The Australian Standards procedure is in agreement with all the situations analyzed.