Particularly efficient steel components can be designed by performing a plastic global analysis of a structure that is also made of high-strength steel.However, plastic design of high-strength steel structures is not embodied in current standards, which is why a broad research study was carried out addressing different aspects of using HSS for plastic design.The paper deals with verified numerical investigations on the rotation capacity of high strength steel I-girders considering realistic true stress strain curves, local plastic instability and damage mechanics approaches to predict ductile crack initiation

As part of the ongoing revision of the Eurocodes, design provisions in EN 1999‐1‐1 on the buckling of longitudinally welded aluminium compression members have been subjected to a critical review. The numerical investigations described in part 1 of the paper were conducted because a need for improvement was identified. In part 2 of the paper, the main observations are presented in qualitative terms. Those observations are: the influence of the allocation of the materials to buckling classes, the influence of the imperfections plus the cross‐section geometry including the position and size of the HAZ within the cross‐section. Part 3 will conclude this paper by discussing the proposed design approaches in detail.

As part of the ongoing revision of the Eurocodes, design provisions in EN 1999‐1‐1 on the buckling of longitudinally welded aluminium compression members have been subjected to a critical review. The numerical investigations described in part 1 of the paper were conducted because a need for improvement was identified. In part 2 the main observations were presented qualitatively. Part 3, the final part of the paper, presents the statistical evaluation of the numerical investigations and the determination of the buckling curves. Two different approaches are conceivable for these buckling curves: conventional buckling curves with explicitly specified imperfection factor and plateau length parameters, and a modified Ayrton‐Perry approach with interpolated parameters. Both approaches are compared with the results of the numerical investigations and with test results.

As part of the ongoing revision of the Eurocodes, design provisions in EN 1999‐1‐1 on the buckling of longitudinally welded aluminium compression members have been subjected to a critical review. Numerical investigations were conducted because a need for improvement was identified. This part 1 of the paper describes the individual steps of the revision and the modifications discussed, which include the introduction of longitudinally welded members. Before going into the numerical investigations in more detail, previous observations are presented regarding buckling classes and plateau lengths. In part 1 of the paper, explanations of the numerical investigations are limited to presenting the modelling of the geometry, the mechanical properties and the imperfections as well as their respective variation in the context of the parametric studies. The results of the numerical investigations and the proposed design approaches will be presented in detail in parts 2 and 3.

ABSTRACTAs part of the ongoing revision of the Eurocodes, the regulations in EN 1999‐1‐1 on the buckling of aluminium compression members were also subjected to a critical review. This resulted in the need to revise the regulations for non‐welded compression members and for longitudinally welded compression members.The introduction of a buckling class C for soft tempers and minor adjustments in the allocation of the individual alloys and tempers to buckling classes A and B can be understood as a fundamental change. The new allocation is presented and explained.The required buckling curve for non‐welded columns made of materials of buckling class C was introduced in prEN 1999‐1‐1. In this context, minor improvements have also been made to buckling curves A and B. The curves are presented and compared with the results of numerical investigations. The comparison is done graphically as well as statistically (based on EN 1990, Annex D). For the design provisions of longitudinally welded aluminium compression members, a more extensive revision was necessary. The design concept was revised and switched to the use of separate buckling curves which are presented here. These curves are also compared with the results of numerical investigations.