PSI - Issue 22

V.M.G. Gomes et al. / Procedia Structural Integrity 22 (2019) 401–406

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V.M.G. Gomes et al. / Structural Integrity Procedia 00 (2018) 000 – 000

bolts matrix is assumed, the fatigue strength of the multiple and single bolted joints becomes closer of each other; - The usual process of producing the bolts holes is the punching since it is a more economic and faster process. It was proved that this process do not compromise the fatigue resistance, even produced better fatigue than bad quality drilled holes as demonstrated in this study. - From a statistical analysis, the S-N curve class 90 proposed in the EC3 for bolted joints is conservative only for very high-cycle fatigue. - The slope of the EC3 S-N curves is not consistent of the joints tested in this research that showed significantly higher slopes, compatible with a fatigue damage dominated by crack initiation. - Regarding failure modes, the failure occurs preferably along the net cross-section, except when the clamping is high and the loading is low enough to deviate the cracking to the gross cross-section. - In the case of single bolt connections with snug tight bolts, despite cracks start in the hole border, they move away from the middle of the hole as the stress amplitude decreases. Acknowledgements The authors express their gratitude to the FASTCOLD RFCS European Project (Grant Agreement No. 745928). Shelter S.A. (Prokopis Tsintzos and Markos Mezari). The SciTech R&D project NORTE-01-0145-FEDER-000022 co-financed by NORTE2020 through FEDER and FCT through the post-doctoral grant SFRH/BPD/107825/2015. Additionally, the authors would like to thank the support from the CONSTRUCT Unit (Institute of R&D in Structures and Construction – UID/ECI/04708/2019) as well as to the doctoral programme iRail- Innovation in Railway Systems and Technologies funding by the Portuguese Foundation for Science and Technology, IP (FCT) through the PhD grant (PD/BD/143141/2019). References CEN, 2005. Eurocode 3: Design of Steel Structures - Part 1-9: Fatigue. Gomes, V., Rodrigues, M., Correia, J., Figueiredo, M., De Jesus, A., Fernandes, A., 2019. Monotonic and Fracture Behaviours of Bolted Connections with Distinct Bolt Preloads and Surface Treatments. Frattura Ed Integrità Strutturale , 13 (48): 304 – 17. https://doi.org/10.3221/IGF ESIS.48.30. ASTM E739-91, 2004. Standard Practice for Statistical Analysis of Linear or Linearized Stress-Life (S-N) and Strain-Life ( ε -N) Fatigue Data, Annual Book of ASTM Standards I (Reapproved): 1 – 7. https://doi.org/10.1520/E0739-10.2.