Lateral torsional buckling of doubly symmetric I-shaped steel members under linear moment gradient

Abstract

Due to technical developments and wider range of applications in the steel structures, significance of the research on structural stability problems become forward. Lateral torsional buckling is a major problem especially for doubly symmetric I-shaped steel members subjected to flexure about their strong axis. If these members are not appropriately braced against lateral deflection and twisting, they are under the risk of failure by lateral torsional buckling prior to the reach their load carrying capacity. In this study, elastic lateral torsional buckling behavior of doubly symmetric I-shaped steel members under linear moment gradient is investigated considering a proposed method, several design standards and codes, approaches from the literature and finite element analysis. Proposed method herein is based on finite difference solution of lateral torsional buckling differential equation considering linear moment gradient. Different unbraced member lengths and various end moment values are considered in order to compare and evaluate these approaches in terms of critical moment and moment modification factor. Analysis results show that lateral torsional buckling is a key issue for doubly symmetric I-shaped steel members that are under flexure and it is reflected satisfactorily with the proposed method considering the design codes and standards, approaches from the literature and finite element analysis results.