Structural member stability verification in the new Part 1‐1 of the second generation of Eurocode 3

Abstract

This two‐part article gives an overview of the developments of the structural member verification in prEN 1993‐1‐1:2020 “Eurocode 3: Design of steel structures – part 1‐1: General rules and rules for buildings”, one of the second generation of Eurocodes. These developments were undertaken by Working Group 1 (WG1) of Subcommittee CEN/TC250/SC3 and by Project Team 1 (SC3.PT1) responsible for drafting the new version of EN 1993‐1‐1. In the past, WG1 collected many topics needing improvement, and the systematic review conducted every five years also yielded topics needing further development. Based on this, the current version of EN 1993‐1‐1 has been developed into a new draft version prEN 1993‐1‐1:2020 enhancing “ease of use”. The technical content of this new draft was laid down at the end of 2019. Many improvements to design rules have been established with respect to structural analysis, resistance of cross‐sections and stability of members. This two‐part article focuses on member stability design rules and deals with the basis for the calibration of partial factors, the introduction of more economic design rules for semi‐compact sections, methods for structural analysis in relation to the appropriate member stability design rules, new design rules for lateral torsional buckling plus other developments and innovations. This first part of the article primarily serves to explain the general background to the European Commission Mandate M/515 that led to the further evolution of the Eurocodes and to illustrate the developments in prEN1993‐1‐1:2020 that pertain to new material grades, partial factors, cross‐sectional classification and structural analysis. These form the necessary background to the changes to member buckling design rules, which are treated more specifically in the second part.

Revision of EN 1993‐1‐1 – Design rules for structural analysis, cross‐sectional resistance and member buckling

“…Further details on the application of the new design rules for LTB and their expansion to various load cases may be found in [5,6].…”

Eigenformbasierte Imperfektionsmethode für Tragwerke mit monosymmetrischen I‐Profilen

“…Es wird aber nicht zwischen Biegeknicken und Biegedrillknicken unterschieden, während dies in den USA gemäß AISC [2] unterschiedlich gehandhabt wird. Nach [3] soll die zukünftige Ausgabe von EC 3 auch Nachweisformate gegen Stabilitätsversagen von einfachsymmetrischen Querschnitten enthalten. Ist zusätzlich ein Moment vorhanden, kann das allgemeine Verfahren nach Abschnitt 6.3.4 verwendet werden.…”

Update on the revision of Eurocode 3 – Evolution by improvement and harmonisation

“…6.3.2.2), which usually concerns profiles without pronounced torsional properties, and the "special case" (EN 1993-1-1, para. 6.3.2.3) for mainly rolled and similar welded cross-sections by a new approach that has been developed in Taras [8] and can be also followed in more detail in [9]. In addition, from the currently two methods for beam-column design only "Method 2" as given in Annex B of the current EN 1993-1-1 has been kept and integrated into the main text.…”