Effect of end connection restraints on the stability of steel beams in bending

The influence of the end restraint conditions on the lateral-torsional buckling of beams is investigated in detail using finite element method. The paper focuses on the limitation of Eurocode 3 regarding the lateral bending and torsional restraint coefficients kz and kθ of the end supports. Theoretical expressions of the coefficients kz and kθ taking into account the minor axis flexural restraint at the support and the end torsional restraint respectively are presented. The introduction of new coefficients zk and kθ representing the actual support conditions in the expression of the elastic critical moment is suggested. A comparison between the elastic critical moments for various beam cross-sections, lengths and various end restraints, obtained from the finite-element method, and those derived from EC3 ENV method, in which the proposed coefficients zk and kθ are introduced, confirms the reliability of these coefficients that model the end support conditions.