Influence of Web Distortions on Inelastic Lateral Buckling Length


JOURNAL OF POLYTECHNIC-POLITEKNIK DERGISI, vol.24, no.1, pp.347-354, 2021 (ESCI) identifier

  • Publication Type: Article / Article
  • Volume: 24 Issue: 1
  • Publication Date: 2021
  • Journal Indexes: Emerging Sources Citation Index (ESCI), TR DİZİN (ULAKBİM)
  • Page Numbers: pp.347-354
  • Gazi University Affiliated: Yes


A critical failure mode is encountered in double symmetric steel I-beams, which is known as lateral distortional buckling (LDB), when the web slenderness ratio of the section is relatively high. LDB is a buckling mode arising through the interaction of the wellknown lateral torsion buckling (LTB) and web buckling, i.e. local buckling (LB), modes. Web slenderness and flange compactness have significant effects on LDB. This study focused on the inelastic LDB behavior of doubly-symmetric steel I-beams. The inelastic behavior increases and web distortions take place with the initiation of yielding in the web (between neutral axis and compression flange) with decreasing beam length. Generally, web distortions are encountered more commonly in the inelastic range of buckling. In this study, analytical limiting unbraced length (Lr) values of the beams with different web slenderness values from the inelastic LTB (Lr) formula of the Turkish Steel Structures Design Code (TSSDC 2016) were compared to the respective finite element results. Lr values were observed to increase due to web distortions. Yielding was determined to be the most influential parameter on web distortions. As a result of LDB, numerical Lr values were higher than the respective analytical estimates from code formulations. However, as the web slenderness of the section increases, the numerical-to-analytical Lr ratio was shown to increase. The study underscored the need to include LDB formulas into the current steel structure design specifications.