DOI QR코드

DOI QR Code

Effects of geometrical parameters on the degree of bending in two-planar tubular DYT-joints of offshore jacket structures

  • Hamid Ahmadi (Centre for Future Materials, University of Southern Queensland) ;
  • Mahdi Ghorbani (Faculty of Civil Engineering, University of Tabriz)
  • Received : 2023.01.10
  • Accepted : 2023.04.06
  • Published : 2023.06.25

Abstract

Through-the-thickness stress distribution in a tubular member has a profound effect on the fatigue behavior of tubular joints commonly found in steel offshore structures. This stress distribution can be characterized by the degree of bending (DoB). Although multi-planar joints are an intrinsic feature of offshore tubular structures and the multi-planarity usually has a considerable effect on the DoB values at the brace-to-chord intersection, few investigations have been reported on the DoB in multi-planar joints due to the complexity of the problem and high cost involved. In the present research, data extracted from the stress analysis of 243 finite element (FE) models, verified based on available parametric equations, was used to study the effects of geometrical parameters on the DoB values in two-planar tubular DYT-joints. Parametric FE study was followed by a set of nonlinear regression analyses to develop six new DoB parametric equations for the fatigue analysis and design of axially loaded two-planar DYT-joints.

Keywords

Acknowledgement

Useful comments of anonymous reviewers on draft version of this paper are highly appreciated.

References

  1. Ahmadi, H. and Alizadeh Atalo, A. (2021), "Geometrical effects on the degree of bending (DoB) of multi-planar tubular KK-joints in jacket substructure of offshore wind turbines", Appl. Ocean Res., 111, 102678. https://doi.org/10.1016/j.apor.2021.102678.
  2. Ahmadi, H. and Amini Niaki, M. (2019), "Effects of geometrical parameters on the degree of bending (DoB) in two-planar tubular DT-joints of offshore jacket structures subjected to axial and bending loads", Mar. Struct., 64, 229-245. https://doi.org/10.1016/j.marstruc.2018.11.008.
  3. Ahmadi, H. and Asoodeh, S. (2016), "Parametric study of geometrical effects on the degree of bending (DoB) in offshore tubular K-joints under out-of-plane bending loads", Appl. Ocean Res., 58, 1-10. https://doi.org/10.1016/j.apor.2016.03.004.
  4. Ahmadi, H., Chamani, S. and Kouhi, A. (2020), "Effects of geometrical parameters on the degree of bending (DoB) in multi-planar tubular XT-joints of offshore structures subjected to axial loading", Appl. Ocean Res., 104, 102381. https://doi.org/10.1016/j.apor.2020.102381.
  5. Ahmadi, H. and Imani, H. (2022), "SCFs in offshore two-planar tubular TT-joints reinforced with internal ring stiffeners", Ocean Syst. Eng., 12(1), 1-22. https://doi.org/10.12989/ose.2022.12.1.001.
  6. Ahmadi, H., Lotfollahi-Yaghin, M.A. and Asoodeh, S. (2015), "Degree of bending (DoB) in tubular K-joints of offshore structures subjected to in-plane bending (IPB) loads: Study of geometrical effects and parametric formulation", Ocean Eng., 102, 105-116. https://doi.org/10.1016/j.oceaneng.2015.04.050.
  7. Ahmadi, H. and Zavvar, E. (2020), "Degree of bending (DoB) in offshore tubular KT-joints under the axial, in-plane bending (IPB), and out-of-plane bending (OPB) loads", Appl. Ocean Res., 95, 102015. https://doi.org/10.1016/j.apor.2019.102015.
  8. American Petroleum Institute (2007), "Recommended practice for planning, designing and constructing fixed offshore platforms: Working stress design: RP 2A-WSD", 21st Ed., Errata and Supplement 3, Washington DC, US.
  9. American Welding Society (2002), "Structural welding code: AWS D 1.1", Miami (FL), US.
  10. Asgarian, B., Mokarram, V. and Alanjari, P. (2014), "Local joint flexibility equations for Y-T and K-type tubular joints", Ocean Syst. Eng., 4(2), 151-167. https://doi.org/10.12989/ose.2014.4.2.151.
  11. Bao, S., Wang, W., Zhou, J., Qi, S. and Li, X. (2022), "Experimental study of hot spot stress for three-planar tubular Y-joint: I. Basic loads", Thin-Wall. Struct., 177, 109418. https://doi.org/10.1016/j.tws.2022.109418.
  12. Bao, S., Wang, W., Li, X., Qi, S. and Zhou, J. (2022), "Experimental study of hot spot stress for three-planar tubular Y-joint: II. Combined loads", Thin-Wall. Struct., 177, 109416. https://doi.org/10.1016/j.tws.2022.109416.
  13. Bao, S., Wang, W., Li, X. and Zhao, H. (2020), "Hot-spot stress caused by out-of-plane bending moments of three-planar tubular Y-joints", Appl. Ocean Res., 100, 102179. https://doi.org/10.1016/j.apor.2020.102179.
  14. Bao, S., Wang, W., Zhou, J. and Li, X. (2023), "Study on hot spot stress distribution of three-planar tubular Y-joints subjected to in-plane bending moment", Mar. Struct., 87, 103326. https://doi.org/10.1016/j.marstruc.2022.103326.
  15. Bomel Consulting Engineers (1994), "Assessment of SCF equations using Shell/KSEPL finite element data", C5970R02.01 REV C.
  16. Chang, E. and Dover, W.D. (1999a), "Parametric equations to predict stress distributions along the intersection of tubular X and DT-joints", Int. J. Fatigue, 21, 619-635. https://doi.org/10.1016/S0142-1123(99)00018-3.
  17. Chang, E. and Dover, W.D. (1999b), "Prediction of degree of bending in tubular X and DT joints", Int. J. Fatigue, 21, 147-161. https://doi.org/10.1016/S0142-1123(98)00060-7.
  18. Chang, E., Dover, W.D. (1996), "Stress concentration factor parametric equations for tubular X and DT joints", Int. J. Fatigue, 18, 363-387. https://doi.org/10.1016/0142-1123(96)00017-5.
  19. Chang, E. (1997), "Parametric study of non-destructive fatigue strength evaluation of offshore tubular welded joints", PhD Thesis, University College London, UK.
  20. Connolly, M.P.M. (1986), "A fracture mechanics approach to the fatigue assessment of tubular welded Y and K-joints", PhD Thesis, University College London, UK.
  21. Det Norske Veritas (2005), "Fatigue design of offshore steel structures", Recommended Practice, DNV RP C203, Norway.
  22. Det Norske Veritas (2008), "Structural design of offshore units (WSD method)", Offshore Standard, DNV OS C201, Norway.
  23. Efthymiou, M. (1988), "Development of SCF formulae and generalized influence functions for use in fatigue analysis", OTJ 88, Surrey, UK.
  24. Eide, O.I., Skallerud, B. and Berge, S. (1993), "Fatigue of large scale tubular joints‒effects of sea water and spectrum loading", Proceedings of the Fatigue under Spectrum Loading and in Corrosive Environments Conference, Technical University of Denmark, Lyngby, Denmark.
  25. Hellier, A.K., Connolly, M. and Dover, W.D. (1990), "Stress concentration factors for tubular Y and T-joints", Int. J. Fatigue, 12, 13-23. https://doi.org/10.1016/j.ijfatigue.2020.105719.
  26. Hobbacher, A.F. (2016), "Recommendations for fatigue design of welded joints and components", IIW Document IIW-2259-15 ex XIII-2460-13/XV-1440-13, International Institute of Welding.
  27. Ju, S.H. (2022), "Increasing the fatigue life of offshore wind turbine jacket structures using yaw stiffness and damping", Renew. Sust. Energ. Rev., 162, 112458. https://doi.org/10.1016/j.rser.2022.112458.
  28. Lee, M.M.K. and Bowness, D. (2002), "Estimation of stress intensity factor solutions for weld toe cracks in offshore tubular joints", Int. J. Fatigue, 24, 861-875. https://doi.org/10.1016/S0142-1123(01)00209-2.
  29. Lie, S.T., Lee, C.K. and Wong, S.M. (2001), "Modeling and mesh generation of weld profile in tubular Y-joint", J. Const. Steel Res., 57, 547-567. https://doi.org/10.1016/S0143-974X(00)00031-6.
  30. Lotfollahi-Yaghin, M.A. and Ahmadi, H. (2010), "Effect of geometrical parameters on SCF distribution along the weld toe of tubular KT-joints under balanced axial loads", Int. J. Fatigue, 32, 703-719. https://doi.org/10.1016/j.ijfatigue.2009.10.008.
  31. Morgan, M.R. and Lee, M.M.K. (1998a), "Parametric equations for distributions of stress concentration factors in tubular K-joints under out-of-plane moment loading", Int. J. Fatigue, 20, 449-461. https://doi.org/10.1016/S0142-1123(98)00011-5.
  32. Morgan, M.R. and Lee, M.M.K. (1998b), "Prediction of stress concentrations and degrees of bending in axially loaded tubular K-joints", J. Const. Steel Res., 45, 67-97. https://doi.org/10.1016/S0143-974X(97)00059-X.
  33. Nassiraei, H. and Rezadoost, P. (2020), "Stress concentration factors in tubular T/Y-joints strengthened with FRP subjected to compressive load in offshore structures", Int. J. Fatigue, 140, 105719. https://doi.org/10.1016/j.ijfatigue.2020.105719.
  34. Nassiraei, H. and Rezadoost, P. (2021a), "Stress concentration factors in tubular T/Y-connections reinforced with FRP under in-plane bending load", Mar. Struct., 76, 102871, https://doi.org/10.1016/j.marstruc.2020.102871.
  35. Nassiraei, H. and Rezadoost, P. (2021b), "Parametric study and formula for SCFs of FRP-strengthened CHS T/Y-joints under out-of-plane bending load", Ocean Eng., 221, 108313. https://doi.org/10.1016/j.oceaneng.2020.108313.
  36. Nassiraei, H. and Rezadoost, P. (2021c), "Stress concentration factors in tubular X-connections retrofitted with FRP under compressive load", Ocean Eng., 229, 108562. https://doi.org/10.1016/j.oceaneng.2020.108562.
  37. Nassiraei, H. and Rezadoost, P. (2021d), "SCFs in tubular X-connections retrofitted with FRP under in-plane bending load", Compos. Struct., 274, 114314. https://doi.org/10.1016/j.compstruct.2021.114314.
  38. Nassiraei, H. and Rezadoost, P. (2021e), "SCFs in tubular X-joints retrofitted with FRP under out-of-plane bending moment", Mar. Struct., 79, 103010. https://doi.org/10.1016/j.marstruc.2021.103010.
  39. Nassiraei, H. and Rezadoost, P. (2022a), "Stress concentration factors in tubular T-joints reinforced with external ring under in-plane bending moment", Ocean Eng., 266, 112551. https://doi.org/10.1016/j.oceaneng.2022.112551.
  40. Nassiraei, H. and Rezadoost, P. (2022b), "Probabilistic analysis of the SCFs in tubular T/Y-joints reinforced with FRP under axial, in-plane bending, and out-of-plane bending loads", Struct., 35, 1078-1097. https://doi.org/10.1016/j.istruc.2021.06.029.
  41. Nassiraei, H. and Rezadoost, P. (2022c), "Development of a probability distribution model for the SCFs in tubular X-connections retrofitted with FRP", Struct., 36, 233-247. https://doi.org/10.1016/j.istruc.2021.10.033.
  42. Newman, J.C. and Raju, I.S. (1986), "Stress intensity factors equations for cracks in three dimensional finite bodies subjected to tension and bending loads", Proceedings of the Conference on Computational Methods in the Mechanics of Fracture, Amsterdam, Netherlands.
  43. Paris, P. and Erdogan, F. (1963), "A critical analysis of crack propagation laws", J. Basic Eng., 85, 528-534. https://doi.org/10.1115/1.3656900.
  44. Prashob, P.S., Shashikala, A.P. and Somasundaran, T.P. (2018), "Effect of FRP parameters in strengthening the tubular joint for offshore structures", Ocean Syst. Eng., 8(4), 409-426. https://doi.org/10.12989/ose.2018.8.4.409.
  45. Shao, Y.B., Du, Z.F. and Lie, S.T. (2009), "Prediction of hot spot stress distribution for tubular K-joints under basic loadings", J. Const. Steel Res., 65, 2011-2026. https://doi.org/10.1016/j.jcsr.2009.05.004.
  46. Shao, Y.B. and Lie, S.T. (2005), "Parametric equation of stress intensity factor for tubular K-joint under balanced axial loads", Int. J. Fatigue, 27, 666-679. https://doi.org/10.1016/j.ijfatigue.2004.11.003.
  47. Shao, Y.B. (2006), "Analysis of stress intensity factor (SIF) for cracked tubular K-joints subjected to balanced axial load", Eng. Fail. Anal., 13, 44-64, https://doi.org/10.1016/j.engfailanal.2004.12.031.
  48. Shao, Y.B. (2007), "Geometrical effect on the stress distribution along weld toe for tubular T- and K-joints under axial loading", J. Const. Steel Res., 63, 1351-1360. https://doi.org/10.1016/j.jcsr.2006.12.005.
  49. Shen, W. and Choo, Y.S. (2012), "Stress intensity factor for a tubular T-joint with grouted chord", Eng. Struct., 35, 37-47. https://doi.org/10.1016/j.engstruct.2011.10.014.
  50. Smedley, P. and Fisher, P. (1991), "Stress concentration factors for simple tubular joints", Proceedings of the International Offshore and Polar Engineering Conference (ISOPE), Edinburgh.
  51. Sunday, K. and Brennan, F. (2021), "A review of offshore wind monopiles structural design achievements and challenges", Ocean Eng., 235, 109409. https://doi.org/10.1016/j.oceaneng.2021.109409.
  52. UK Department of Energy (1983), "Background notes to the fatigue guidance of offshore tubular joints", UK DoE, London, UK.
  53. Wang, L., Kolios, A., Liu, X., Venetsanos, D. and Cai, R. (2022), "Reliability of offshore wind turbine support structures: A state-of-the-art review", Renew. Sust. Energ. Rev., 161, 112250. https://doi.org/10.1016/j.rser.2022.112250.