PSI - Issue 38

Antti Ahola et al. / Procedia Structural Integrity 38 (2022) 457–465 Ahola et al. / Structural Integrity Procedia 00 (2021) 000 – 000

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strength is proposed for single-sided weldments. However, this observation was based on the limited number of tests, and would require further verification by experimental fatigue testing. In fully-penetrated K-butt welds, the longitudinal irregularities at the weld root can be avoided, and the highest fatigue performance can thus be obtained in such weld configurations. The results obtained employing the ENS concept ( r ref = 1.0 mm) showed that for the SSFW specimens failing from the weld root had lower fatigue capacity than the DSFW specimens failing from the weld root, Fig. 5. These findings should be considered when evaluating the critical location of SSFW joints (weld toe or root) – the ENSs with with r ref = 1.0 mm for both weld toe and weld root do not necessarily correctly indicate the critical location. 4. Conclusions This study provided an overview on the fatigue strength capacity of SSFWs in the transverse attachment joint and longitudinal web-to-flange joint configurations. Based on the experimental fatigue test data and subsequent analyses, the following conclusions can be drawn: • The transverse NLC SSFW joints made of S355 and S1100 grades showed lower fatigue strength capacity than the corresponding DSFW joints. In all cases, the data points were above the design curve FAT80 but a division to SSFW (FAT80) and DSFW (FAT90) joints, provided in the crane standard (EN 13001-3-1, 2018), is logical based on the experimental findings. • Intermittent welding did not reduce the fatigue capacity of SSFW joints in the transverse NLC attachments compared to the continuous welding although in the longitudinal welds, the intermittent welding should be avoided or, at least, carefully considered in the beams with longitudinal seams. • The K-butt welding of web-to-flange connections in the I sections have shown the highest fatigue capacity in the automated/mechanized longitudinal welds but SSFWs have shown similar fatigue performance to the DSFW joints with non-fused weld root. Acknowledgements The authors wish to thank Business Finland for the funding in the Intelligent Steel Applications (ISA) project. Furthermore, the corresponding author express the gratitude for the Jenny and Antti Wihuri foundation for their financial support to conduct the research work, and the analysis of the experimental results. References Ahola, A., Skriko, T., Björk, T., 2019. Experimental investigation on the fatigue strength assessment of welded joints made of S1100 ultra-high strength steel in as-welded and post-weld treated condition. In: Zingoni, A. (Ed.), Proceedings of the 7th International Conference on Structural Engineering, Mechanics and Computation (SEMC 2019). Cape Town, South Africa, 2-4 September 2019. pp. 1254 – 1259. Ahola, A., Skriko, T., Lipiäinen, K., Björk, T., 2021. On the weld root fatigue strength and improvement techniques of non-load-carrying transverse attachment joints with single-sided fillet weld and made of mild and ultra-high-strength steels. Under work, submitted to journal. Baumgartner, J., Bruder, T., 2013. An efficient meshing approach for the calculation of notch stresses. Weld. World 57, 137 – 145. Blodgett, O.W., 2008. Re-examining intermittent fillet welds, Part II. Weld. Des. Fabr. 81, 10 – 14. DNVGL-RP-C203, 2016. Fatigue Design of Offshore Steel Structures.

EN 13001-3-1, 2018. Cranes. General Design. Part 3-1: Limit States and proof competence of steel structure. EN 1993-1-1, 2005. Eurocode 3: Design of steel structures - Part 1-1: General rules and rules for buildings. EN 1993-1-8, 2005. Eurocode 3: Design of steel structures - Part 1-8: Design of joints. EN 1993-1-9, 2005. Eurocode 3: Design of steel structures - Part 1-9: Fatigue. Gurney, T.R., Maddox, S.J., 1973. A re-analysis of fatigue data for welded joints in steel. Weld. Res. Int. 3, 1 – 54.

Hobbacher, A., 2016. Recommendations for Fatigue Design of Welded Joints and Components, 2nd ed. Springer International Publishing, Cham. Khedmati, M.R., Rastani, M., Ghavami, K., 2007. Numerical study on the permissible gap of intermittent fillet welds of longitudinally stiffened plates under in plane axial compression. J. Constr. Steel Res. 63, 1415 – 1428.