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Research on stress distributions around welds of three-planar tubular Y-joints under out-of-plane bending moment

  • Shiliu Bao (College of Civil and Transportation Engineering, Hohai University) ;
  • Wenhua Wang (Faculty of Infrastructure Engineering, Dalian University of Technology) ;
  • Jikai Zhou (College of Civil and Transportation Engineering, Hohai University) ;
  • Xin Li (Faculty of Infrastructure Engineering, Dalian University of Technology)
  • Received : 2023.02.11
  • Accepted : 2023.10.12
  • Published : 2023.10.25

Abstract

Marine structures including offshore wind turbines (OWTs) always work under cyclic loads, which arouses much attention on the fatigue design. The tripod substructure is one of the typical foundation forms for fixed OWTs. The three-planar tubular Y-joint (3Y joint) is one of the important components in fatigue design as it is most likely to have cracks. With the existence of the multiplanar interaction effect, calculating the hot spot stress (HSS) of 3Y joints is complicated. To assist with fatigue design, the distributions of stress concentration factor (SCF) and multiplanar interaction factor (MIF) along weld toe curves induced by the out-of-plane bending moment are explored in this study. An FE analysis method was first developed and verified against experimental results. This method was applied to build a numerical database including 1920 FE models covering common ranges of geometric parameters. A parametric study has been carried out to reveal the distribution patterns of SCF and MIF. After multidimensional nonlinear fittings, SCF and MIF distribution formulas have been proposed. Accuracy and reliability checking prove that the proposed formulas are suitable for calculating the HSS of 3Y joints.

Keywords

Acknowledgement

The National Natural Science Foundation of China (Grant No. 52101311), Fundamental Research Funds for Center Universities (Grant Nos. B220202008), and Jiangsu Postdoctoral Research Funding (Grant No. 2021K286B) are all acknowledged for their financial support, which is much appreciated by the authors. We take this opportunity to thank the insightful opinions given to the drafts of this paper by anonymous reviewers.

References

  1. Ahmadi, H. and Kouhi, A. (2020), "Stress concentration factors of multi-planar tubular XT-joints subjected to out-of-plane bending moments", Appl. Ocean Res., 96(102058). https://doi.org/10.1016/j.apor.2020.102058.
  2. Ahmadi, H. and Lotfollahi-Yaghin, M.A. (2015a), "Stress concentration due to in-plane bending (IPB) loads in ring-stiffened tubular KT-joints of offshore structures: Parametric study and design formulation", Appl. Ocean Res., 51, 54-66. https://doi.org/10.1016/j.apor.2015.02.009.
  3. Ahmadi, H. and Zavvar, E. (2015), "Stress concentration factors induced by out-of-plane bending loads in ring-stiffened tubular KT-joints of jacket structures", Thin Wall Struct., 91, 82-95. https://doi.org/10.1016/j.tws.2015.02.011.
  4. Ahmadi, H. and Zavvar, E. (2016), "The effect of multi-planarity on the SCFs in offshore tubular KT-joints subjected to in-plane and out-of-plane bending loads", Thin Wall Struct., 106, 148-165. https://doi.org/10.1016/j.tws.2016.04.020.
  5. 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.
  6. Ahmadi, H. and Ziaei Nejad, A. (2017), "Geometrical effects on the local joint flexibility of two-planar tubular DK-joints in jacket substructure of offshore wind turbines under OPB loading", Thin Wall Struct., 114, 122-133. https://doi.org/10.1016/j.tws.2017.02.001.
  7. Ahmadi, H., Lotfollahi-Yaghin, M.A. and Aminfar, M.H. (2011), "Geometrical effect on SCF distribution in uni-planar tubular DKT-joints under axial loads", J. Construct. Steel Res., 67(8), 1282-1291. https://doi.org/10.1016/j.jcsr.2011.03.011.
  8. 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.
  9. Ahmadi, H., Lotfollahi-Yaghin, M.A. and Yong-Bo, S. (2013), "Chord-side SCF distribution of central brace in internally ring-stiffened tubular KT-joints: A geometrically parametric study", Thin Wall Struct., 70, 93-105. https://doi.org/10.1016/j.tws.2013.04.011.
  10. Ahmadi, H., Lotfollahi-Yaghin, M.A., Yong-Bo, S. and Aminfar, M.H. (2012), "Parametric study and formulation of outer-brace geometric stress concentration factors in internally ring-stiffened tubular KT-joints of offshore structures", Appl. Ocean Res., 38, 74-91. https://doi.org/10.1016/j.apor.2012.07.004.
  11. API RP 2A-WSD (2014), Planning, Designing, and Constructing Fixed Offshore Platforms-Working Stress Design, American Petroleum Institute (API); Washington DC, USA.
  12. AWS D1.1/D1.1M:2010 (2010), Structural Welding Code-Steel, American Welding Society (AWS), Miami, USA.
  13. Bao, S., Li, X. and Wang, B. (2019), "Study on hot spot stress of three-planar tubular Y-joints under combined axial loads", Thin Wall Struct., 140, 478-494. https://doi.org/10.1016/j.tws.2019.03.025.
  14. Bao, S., Wang, W., Chai, Y.H. and Li, X. (2020a), "Hot spot stress parametric equations for three-planar tubular Y-joints subject to in-plane bending moment", Thin Wall Struct., 149(106648). https://doi.org/10.1016/j.tws.2020.106648
  15. Bao, S., Wang, W., Li, X. and Zhao, H. (2020b), "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.
  16. Bao, S., Wang, W., Zhou, J., Qi, S. and Li, X. (2022a), "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.
  17. Bao, S., Wang, W., Li, X., Qi, S. and Zhou, J. (2022b), "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.
  18. Bao, S., Wang, W., Li, X. and Zhou, J. (2022c), "Stress concentration factor distribution formulas for three-planar tubular Y-joints under axial force", Ocean Eng., 265, 112687. https://doi.org/10.1016/j.oceaneng.2022.112687.
  19. Cao, J., Yang, G. and Packer, J.A. (1997), FE Mesh Generation for Circular Tubular Joints with or without Cracks, Honolulu, USA.
  20. Chang, E. (1999), "Parametric equations to predict stress distributions along the intersection of tubular X and DT-joints", Int. J. Fatigue, 21(6), 619-635. https://doi.org/10.1016/S0142-1123(99)00018-3.
  21. Chang, E. and Dover, W.D. (1999), "Prediction of stress distributions along the intersection of tubular Y and T-joints", Int. J. Fatigue, 21(4), 361-381. https://doi.org/10.1016/S0142-1123(98)00083-8.
  22. Chiew, S., Zhang, J., Shao, Y. and Qiu, Z. (2012), "Experimental and numerical analysis of complex welded tubular DKYY-joints", Adv. Struct. Eng., 15(9), 1573-1582. https://doi.org/10.1260/1369-4332.15.9.1573.
  23. CIDECT (2001), Design guide for circular and rectangular hollow section welded joints under fatigue loading, Comite International pour le Developpement et l'Etude de la Construction Tubulaire (CIDECT); Germany.
  24. DNV-RP-C203 (2016), Fatigue Design of Offshore Steel Structures, Det Norske Veritas (DNV); Norway.
  25. DoE (1984), Offshore Installations: Guidance on Design and Construction, Department of Energy; UK.
  26. DoE (1988), Investigation into the Differences between the Measured Hot-Spot Stress When Derived by Either Linear or Non-Linear Extrapolation Techniques, Department of Energy; UK.
  27. Gao, F., Shao, Y.B. and Gho, W.M. (2007), "Stress and strain concentration factors of completely overlapped tubular joints under lap brace IPB load", J. Construct. Steel Res., 63(3), 305-316. https://doi.org/10.1016/j.jcsr.2006.05.007.
  28. Gho, W.M., Fung, T.C. and Soh, C.K. (2003), "Stress and strain concentration factors of completely overlapped tubular K(N) joints", J. Struct. Eng., 129(1), 21-29. https://doi.org/10.1061/~ASCE!0733-9445~2003!129:1~21!
  29. Gho, W.M., Gao, F. and Yang, Y. (2005), "Load combination effects on stress and strain concentration of completely overlapped tubular K(N)-joints", Thin Wall Strcut., 43(8), 1243-1263. https://doi.org/10.1016/j.tws.2005.03.004.
  30. Hectors, K. and De Waele, W. (2020), "A numerical framework for determination of stress concentration factor distributions in tubular joints", Int. J. Mech. Sci., 174(105511). https://doi.org/10.1016/j.ijmecsci.2020.105511.
  31. Hellier, A.K., Connolly, M.P. and Dover, W.D. (1990), "Stress concentration factors for tubular Y- and T-joints", Int. J. Fatigue, 12(1), 13-23. https://doi.org/10.1016/0142-1123(90)90338-F
  32. Hobbacher, A.F. (2016), Recommendations for Fatigue Design of Welded Joints and Components, Springer International Publishing, Heidelberg, Germany.
  33. Jiang, Y., Yuan, K. and Cui, H. (2018), "Prediction of stress concentration factor distribution for multi-planar tubular DT-joints under axial loads", Mar. Struct., 61, 434-451. https://doi.org/10.1016/j.marstruc.2018.06.017
  34. Karamanos, S.A., Romeijn, A. and Wardenier, J. (1999), "Stress concentrations in multi-planar welded CHS XX-connections", 50(3), 259-282. https://doi.org/10.1016/S0143-974X(98)00244-2
  35. Karamanos, S.A., Romeijn, A. and Wardenier, J. (2000), "Stress concentrations in tubular DT-joints for fatigue design", J. Struct. Eng., 126(11), 1320-1330. https://doi.org/10.1061/(ASCE)0733-9445(2000)126:11(1320).
  36. Lecheb, S., Nour, A., Chellil, A., Mechakra, H., Ghanem, H. and Kebir, H. (2015), "Dynamic prediction fatigue life of composite wind turbine blade", Steel Compos. Struct., 8(3), 673-691. https://doi.org/10.12989/scs.2015.18.3.673.
  37. Lie, S.T., Lee, C.K. and Wong, S.M. (2001), "Modelling and mesh generation of weld profile in tubular Y-joint", J. Construct. Steel Res., 57(5), 547-567. https://doi.org/10.1016/S0143-974X(00)00031-6.
  38. Liu, G., Zhao, X. and Huang, Y. (2015), "Prediction of stress distribution along the intersection of tubular T-joints by a novel structural stress approach", Int. J, Fatigue., 80, 216-230. https://doi.org/10.1016/j.ijfatigue.2015.05.021.
  39. Lloyd's Register of Shipping (1992), "Stress concentration factors for tubular complex joints", OTH 91 353; Health and Safety Executive.
  40. Lloyd's Register of Shipping (1997), "Stress concentration factors for simple tubular joints", OTH 354, Health and Safety Executive.
  41. 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(4), 703-719. https://doi.org/10.1016/j.ijfatigue.2009.10.008.
  42. Ma, C. and Zi, G. (2022), "Comparative study on the structural behavior of a transition piece for offshore wind turbine with jacket support", Steel Compos. Struct., 43(3), 363-373. https://doi.org/10.12989/scs.2022.43.3.363.
  43. Morgan, M.R. and Lee, M.M.K. (1998), "Parametric equations for distributions of stress concentration factors in tubular K-joints under out-of-plane moment loading", Int. J. Fatigue., 20(6), 449-461. https://doi.org/10.1016/S0142-1123(98)00011-5.
  44. 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.
  45. Nassiraei, H. and Rezadoost, P. (2021a), "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.
  46. Nassiraei, H. and Rezadoost, P. (2021b), "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
  47. Nassiraei, H. and Rezadoost, P. (2021c), "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.
  48. Nassiraei, H. and Rezadoost, P. (2021d), "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.
  49. Nassiraei, H. and Rezadoost, P. (2021e), "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.
  50. 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.
  51. 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", Structures, 35, 1078-1097. https://doi.org/10.1016/j.istruc.2021.06.029.
  52. Nassiraei, H. and Rezadoost, P. (2022c), "Development of a probability distribution model for the SCFs in tubular X-connections retrofitted with FRP", Structures, 36, 233-247. https://doi.org/10.1016/j.istruc.2021.10.033.
  53. Nassiraei, H. and Rezadoost, P. (2023), "Stress concentration factors in tubular T-joints stiffened with external ring under axial load", Ocean Syst. Eng., 13(1), 43-55. https://doi.org/10.12989/ose.2023.13.1.043.
  54. Qin, Y., Zhang, J.C., Shi, P., Chen, Y.F., Xu, Y.H. and Shi, Z.Z. (2021), "Further study on improvement on strain concentration in through-diaphragm connection", Steel Compos. Struct., 39(2), 135-148. https://doi.org/10.12989/scs.2021.39.2.135.
  55. Shao, Y., Du, Z. and Lie, S. (2009), "Prediction of hot spot stress distribution for tubular K-joints under basic loadings", J. Construct. Steel Res., 65(10-11), 2011-2026. https://doi.org/10.1016/j.jcsr.2009.05.004.
  56. Stavridou, N., Efthymiou, E., Gerasimidis, S. and Baniotopoulos, C.C. (2015), "Investigation of stiffening scheme effectiveness towards buckling stability enhancement in tubular steel wind turbine towers", Steel Compos. Struct., 19(5), 1115-1144. https://doi.org/https://www.webofscience.com/wos/woscc/full-record/WOS:000367923000003. https://doi.org/10.12989/scs.2015.19.5.1115
  57. Tong, L.W., Chen, K.P., Xu, G.W. and Zhao, X.L. (2019), "Formulae for hot-spot stress concentration factors of concrete-filled CHS T-joints based on experiments and FE analysis", Thin Wall Struct., 136, 113-128. https://doi.org/10.1016/j.tws.2018.12.013.
  58. Wu, X.G., Zhang, X.S., Zhang, Q.T., Zhang, D., Yang, X.J., Qiu, F.Q., Park, S. and Kang, T. (2022), "Design and behavior of 160 m-tall post-tensioned precast concrete-steel hybrid wind turbine tower", Steel Compos. Struct., 44(3), 393-407. https://doi.org/10.12989/scs.2022.44.3.393.
  59. Yan, M., Guo, Z., Li, C.F., Liu, Y. and Wang, X.R. (2021), "Effect of welding defects on mechanical properties of welded joints subjected to temperature", Steel Compos Struct., 40(2), 193-202. https://doi.org/10.12989/scs.2021.40.2.193.
  60. Zheng, J., Nakamura, S., Ge, Y., Chen, K. and Wu, Q. (2018), "Formulation of stress concentration factors for concrete-filled steel tubular (CFST) T-joints under axial force in the brace", Eng. Struct., 170, 103-117. https://doi.org/10.1016/j.engstruct.2018.05.066