Abstract
This thesis investigates the fatigue strength assessment of welded structures based on established standards and guidelines, including the IIW Recommendations, the FKM Guideline, EN¿13001, EN¿13445, and EN¿1993. The IIW Recommendations provide guidance for assessing the fatigue strength of welded steel structures, with their comprehensive notch classification system forming the basis for other standards. The FKM Guideline offers a general procedure for evaluating both static and fatigue strength of bar- and plate-shaped components in mechanical engineering. EN¿13001 defines the design requirements for cranes, while EN¿13445 specifies requirements for unfired pressure vessels. EN¿1993 governs the static and dynamic design of steel structures. The first objective of this thesis is to identify the differences among these standards in terms of modification factors on fatigue resistance, loading conditions, and safety concepts. The second objective is to determine fatigue-relevant stresses in a component under defined loading using the Finite Element Method (FEM), and to perform fatigue strength verification of the component both analytically and with the software IBF Fatigue. Finally, the calculated fatigue resistances perpendicular to the weld direction, as given in the various standards, are compared. For the analysis, an FE shell model of the press lower beam of a hydraulic press with a compression force of¿20¿000¿kN was used. The plate thicknesses range from¿40¿mm¿to¿242¿mm, and the model contains several butt and K welds that exhibit highly variable loading conditions. The results show significant differences depending on the reference standard. The most conservative result at a defined location is yielded by EN 13445, with a fatigue resistance amounting to only¿32%¿of that obtained under¿EN¿13001. The IIW Recommendations, the FKM Guideline, and¿EN¿1993¿produce similar fatigue resistances ranging from¿42%¿to¿47%¿of the¿EN¿13001¿value. The main causes of these large deviations are the omission of the plate thickness correction factor in¿EN¿13001¿and the absence of the beneficial effect of stress relief annealing on fatigue resistance in¿EN¿13445. This study provides a foundation for developing a unified approach to the assessment of welded steel joints in conjunction with FEM analysis.
| Translated title of the contribution | Simulation based Comparison of the Fatigue Strength of Welded Structures based on the IIW, FKM, EN 13001, EN 13445, Eurocode 3 Guidelines |
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| Original language | German |
| Qualification | Dipl.-Ing. |
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| Supervisors/Advisors |
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| Award date | 27 Mar 2026 |
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| Publication status | Published - 2026 |
Bibliographical note
embargoed until 24-02-2031Keywords
- Fatigue Resistance
- Welded Structures
- EN 1993
- EN 13001
- EN 13445
- IIW Guidline
- FKM Guidline
- Finite Element Analysis
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