Biegeknicken und Biegedrillknicken aus der Haupttragebene

Flexural buckling and lateral torsional buckling out of the main plane.

Whereas design rules for flexural buckling in Eurocode 3 based on buckling curves are common for Europe, the design rules for lateral torsional buckling are not; there are various alternative proposals originating from various authors which are not consistent and therefore have been made subject to National decisions by opening notes. This paper demonstrates that flexural buckling and lateral torsional buckling have a common mechanical basis resulting in a single formula for equivalent geometrical imperfections and also in a single formula for flexural and lateral torsional buckling curves derived from these imperfections. In conclusion a consistent, clear and simple method for flexural and lateral torsional buckling assessment is obtained, the reliability of which could be proved to be in conformity with the safety requirement of the Eurocodes by test evaluations according to EN 1990. The method is applicable for numerical assessments (e.g. FEM) as well as for hand calculations and also allows to take additional loading in bending and torsion into account.