Application of level 1 interaction formulae to class 4 sections

Evaluations are carried out to check the validity of Level 1 interaction formulae to class 4 sections. These interaction formulae are now given in Annex A of prEN 1993-1-1 and called method B. Within these evaluations the standard cases of thin-walled I-sections as well as thinwalled hollow sections subjected to compression and uniaxial bending and compression and biaxial bending are taken into account. The results of several tests and ultimate load calculations are compared with the results received by using the interaction formulae. It is shown that the Level 1 interaction formulae of the future EN code are sufficient economical and safe.