Numerical Validation of the Eurocode 3 Design Rules for Lateral-Torsional Buckling of I-Beams

This work presents a numerical study of the behaviour of steel I-beams subjected to lateral torsional buckling. The results obtained are compared with the beam stability design curves from Eurocode 3.

The EN version of part 1-1 of this Eurocode introduces significant changes in the evaluation of the lateral torsional buckling [

1

] resistance of unrestrained beams, that improve the too conservative approach of part 1-1 of Eurocode 3 from 1992 in case of non uniform bending. The EN version of the Eurocode 3 [

2

] presents two methods for the evaluation of the design buckling resistance moment of laterally unrestrained I-beams subject to major axis bending. One of these methods is similar to the one already prescribed in Eurocode 3 of 1992, while the other presents some differences in the buckling curves used. Further, it explicitly allows taking into account the influence of the loading type, through the introduction of a correction factor. The present study aims at evaluating the behavior of these two methods and to analyse the influence of the loading type in the first method through the use of that correction factor.

Aiming the safety evaluation of the design formulae, a statistical analysis of the results is performed on the basis of the EN 1990-Annex D [

3

] in a companion paper [

4

].