Computers and Concrete

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Evaluation of shear-key misalignment in grouted connections for offshore wind tower under axial loading

  • Seungyeon Lee (School of Civil, Environmental and Architectural Engineering, Korea University) ;
  • Seunghoon Seo (School of Civil, Environmental and Architectural Engineering, Korea University) ;
  • Seungjun Kim (School of Civil, Environmental and Architectural Engineering, Korea University) ;
  • Chulsang Yoo (School of Civil, Environmental and Architectural Engineering, Korea University) ;
  • Goangseup Zi (School of Civil, Environmental and Architectural Engineering, Korea University)
  • Received : 2024.01.07
  • Accepted : 2024.02.16
  • Published : 2024.05.25
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Abstract

In this study, we investigated the effect of shear-key placement on the performance of grouted connections in offshore wind-turbine structures. Considering the challenges of height control during installation, we designed and analyzed three grouted connection configurations. We compared the crack patterns and strain distribution in the shear keys under axial loading. The results indicate that the misalignment of shear keys significantly influences the ultimate load capacity of grouted connections. Notably, when the shear keys were positioned facing each other, the ultimate load decreased by approximately 15%, accompanied by the propagation of irregular cracks in the upper shear keys. Furthermore, the model with 50% misalignment in the shear-key placement exhibited the highest ultimate strength, indicating a more efficient load resistance than the reference model. This indicates that tensile-load-induced cracking and the formation of compressive struts in opposite directions significantly affect the structural integrity of grouted connections. These results demonstrate the importance of considering buckling effects in the design of grouted connections, particularly given the thin and slender nature of the inner sleeves. This study provides valuable insights into the design and analysis of offshore wind-turbine structures, highlighting the need for refined design formulas that account for shifts in shear-key placement and their structural implications.

Keywords

Acknowledgement

This work was supported by Korea Institute of Energy Technology Evaluation and Planning(KETEP) grant funded by the Korea government(MOTIE)(20213030020110) and by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIT) (No. NRF-2021R1A5A1032433).

References

  1. Aboubakr, A.A.M. (2020), "Behaviour study of grouted connection for offshore wind turbine structures with brittle cement based grouts", Doctoral Dissertation, Universitat Kassel, Kassel, Germany.
  2. API (2007), Recommended Practice for Planning, Designing and Constructing Fixed Offshore Platforms-Working Stress Design, American Petroleum Institute, Washington, D.C., USA.
  3. Aritenang, W., Elnashai, A.S., Dowling, P.J. and Carroll, B.C. (1990), "Failure mechanisms of weld-beaded grouted pile/sleeve connections", Marine Struct., 3, 391-417. https://doi.org/10.1016/0951-8339(90)90011-F.
  4. Billington, C. and Lewis, G. (1978), "The strength of large diameter grouted connections", Offshore Technology Conference, Houston, TX, USA, May.
  5. Billington, C.J. and Tebbett, I.E. (1980), "The basis for new design formulae for grouted jacket to pile connections", Offshore Technology Conference, Houston, TX, USA, May.
  6. CEB (1990), CEB/FIP Model Code 1990, Comite Euro-International du Beton, Lausame, Switzerland.
  7. CEB (2010), CEB/FIP Model Code 2010, Comite Euro-International du Beton, Thomas Telford, London.
  8. Chen, T. (2020), "Hysteretic behavior of grouted connections in offshore wind turbine support structures", J. Constr. Steel Res., 164, 105783. https://doi.org/10.1016/j.jcsr.2019.105783.
  9. Chen, T., Wang, X., Gu, X., Zhao, Q., Yuan, G. and Liu, J. (2019b), "Axial compression tests of grouted connections in jacket and monopole offshore wind turbine structures", Eng. Struct., 196, 109330. https://doi.org/10.1016/j.engstruct.2019.109330.
  10. Chen, T., Wang, X., Zhao, Q. and Yuan, G. (2019a), "A numerical investigation on grouted connections for offshore wind turbines under combined loads", J. Marine Eng. Technol., 18, 134-146. https://doi.org/10.1080/20464177.2018.1507443.
  11. Dallyn, P., El-Hamalawi, A., Palmeri, A. and Knight, R. (2015), "Experimental testing of grouted connections for offshore substructures: A critical review", Struct., 3, 90-108. https://doi.org/10.1016/j.istruc.2015.03.005.
  12. DNV GL (2018), DNVGL-ST-0126: Support Structures for Wind Turbines, Hovik. Norway.
  13. Fehling, E., Leutbecher, T., Schmidt, M. and Ismail M.(2013), "Grouted connections for offshore wind turbine structures: Part 2: Structural modelling and design of grouted connections", Steel Constr., 6, 216-228. https://doi.org/10.1002/stco.201310031.
  14. ISO (2007), ISO 19902: Petroleum and Natural Gas Industries - Fixed Steel Offshore Structures, International Organization for Standardization, London, UK.
  15. Jiang, Z. (2021), "Installation of offshore wind turbines: A technical review", Renewab. Sustainab. Energy Rev., 139, 110576. https://doi.org/110579. 10.1016/j.rser.2020.110576.
  16. Karsan, D.I., Krahl, N.W. (1984), "New API equation for grouted pile-to-structure connections", Offshore Technology Conference, Houston, TX, USA, May.
  17. Kim, K., Plodpradit, P., Kim, B. Sinsabvarodom, C. and Kim, S. (2014), "Interface behavior of grouted connection on monopile wind turbine offshore structure", Int. J. Steel Struct., 14(3), 439-446. https://doi.org/10.1007/s13296-014-3001-1.
  18. Krahl, N.W. and Karasan, D.I. (1985), "Axial strength of grouted pile-to-sleeve connections", J. Struct. Eng., 111, 889-905. https://doi.org/10.1061/(ASCE)0733-9445(1985)111:4(889).
  19. Lamport, W., Jirsa, J. and Yura, J. (1991), "Strength and behavior of grouted pile to sleeve connections", Struct. Eng., 117, 2477-2498. https://doi.org/10.1061/(ASCE)0733-9445(1991)117:8(2477).
  20. Lee, J.H., Won, D.H., Jeong, Y.J., Kim, S.H. and Kang, Y.J. (2017), "Interfacial shear behavior of a high-strength pile to sleeve grouted connection", Eng. Struct., 151, 704-723. https://doi.org/10.1016/j.engstruct.2017.08.035.
  21. Lotsberg, I. (2013), "Structural mechanics for design of grouted connections in monopile wind turbine structures", Marine Struct., 32, 113-135. https://doi.org/10.1016/j.marstruc.2013.03.001.
  22. Moller, A. (2006), "Efficient offshore wind turbine foundations", Wind Eng., 29(5), 463-470. https://doi.org/10.1260/030952405775992580.
  23. NORSOK (2013), NORSOK Standard N-004 - Design of Steel Structures, NORSOK, Hovik, Norway.
  24. Raba, A. (2018), "Fatigue behavior of submerged axially loaded grouted connections", Gottfried Wilhelm Leibniz University, Hannover, Germany.
  25. Sele, A. and Kjeoy, H. (1989), "Background for the new design equations for grouted connections in the DNV draft rules for fixed offshore structure", Offshore Technology Conference, Hounston, TX, USA, May.
  26. Sele, A. and Skjolde, M. (1993.), "Design provisions for offshore grouted construction", Offshore Technology Conference, Hounston, TX, USA, May.
  27. TechNavio (2022), Global Offshore Wind Power Market 2023- 2027, TechNavio, Toronto, ON, Canada. 
  28. Tziavos, I., Hemida, H., Dirar, S., Papaelias, M., Metje, N. and Baniotopoulos, C. (2020), "Structural health monitoring of grouted connections for offshore wind turbines by means of acoustic emission: An experimental study", Renewab. Energy, 147, 130-140. https://doi.org/10.1016/j.renene.2019.08.114.
  29. US Department of Energy (2017), "Offshore wind technologies market update", US Department of Energy, Washington, D.C., USA.
  30. Vernardos, M., Gantes, J., Badogiannis, G. and Lignos, A. (2021), "Experimental and numerical investigation of steel-grout-steel sandwich shells for wind turbine towers", J. Constr. Steel Res., 184, 106815. https://doi.org/10.1016/j.jcsr.2021.106815.
  31. Wang, W. and Han, L.H. (2017), "Behaviour of grout-filled double skin steel tubes under compression and bending: Experiments", Thin Wall. Struct., 116, 307-319. https://doi.org/10.1016/j.tws.2017.02.029.