PSI - Issue 57

Mladen Lukić et al. / Procedia Structural Integrity 57 (2024) 550 – 559 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

551

2

1. Introduction The verification of the fatigue resistance of constructional steelwork follows particular design rules compiled in Part 1-9 of Eurocode 3 that was released in 2005 as harmonised European design standard EN 1993-1-9 (2005) and put into power by all CEN member states together with corresponding National Annexes. In 2012, the European Commission assigned the mandate M/515 to the European Committee for Standardization (CEN) to develop a next generation of the Eurocode design standards. According to this mandate, the whole Eurocode series was to be updated under the responsibility of Technical Committee 250 “Structural Eurocodes” (CEN/TC 250) with respect to new design methods, new materials and new social requirements. An improvement of the ease of use addressing the needs of practitioners (competent engineers being the primary target audience) and a reduction of the Nationally Determined Parameters (NDPs) through a deepened harmonisation were two main goals of this Eurocode revision. The development of the next generation of Eurocode design standards was delegated to small, and focussed, project teams. The authors of this paper formed the project team SC3.T8 responsible for the revision of EN 1993-1-9 (2005). The project team started its work in 2018 and finalized it in July 2021 with the delivery of the final document. This final document was discussed and commented by the responsible CEN working group CEN/TC 250/SC 3/WG 9 and technically approved in November 2021 by CEN/TC 250 Subcommittee 3 (SC 3) that has the overall responsibility for design standards relating to constructional steelwork within CEN/TC 250. After this approval, minor modifications to the final document were implemented by WG 9 and sent to CEN/TC 250 through SC 3 Decision 07/2022 as draft standard prEN 1993-1-9 (2022) in March 2022 for the CEN Enquiry process among the CEN member states. Depending on the response from the CEN Enquiry, the draft standard prEN 1993-1-9 (2022) will be amended as a FprEN (final draft European Standard) for Formal Vote by the CEN member states whose start is planned for October 2024. The final publication of the next generation of Eurocode design standards, together with the corresponding NationalAnnexes (NAs), depends on the CEN memberstates. This paperpresents the significant aspects of the draft standard prEN 1993-1-9 (2022) to an international audience for the first time. The most important changes being highlighted, this paperis intended to provide an overview of these changes in comparison with the current EN 1993 1-9 (2005).

Nomenclature ENS

effective notch stress HFMI High Frequency Mechanical Impact treatment HS hot spot   C detail category   D constant amplitude fatigue limit  nominal stress m

slope parameter of fatigue resistance curve (S-N curve)

2. Structure and scope of prEN 1993-1-9 (2022) The revision of EN 1993-1-9 (2005) was to be based on the following fundamental requirements: • Harmonisation with other EN standards e.g. EN 1993-1-11, EN 1993-2, EN 1090-2 and EN ISO 5817; • Integration of new experimental results; • Expansion of fatigue analysis methods and rules to accord with modern design practice; • Integration of new execution methodologies; • Reducing the number of NDPs and NCCIs (Non Contradictory Complementary Information) given in certain NAs and drawn from a variety of sources on the basis of an evaluation of all available NAs. Where reasonably practical, revisions were intended to focus on providing clarity on simplified verification approaches and the avoidance of additional and/or empirical rules for particular structures, or structural-element types.