Ocean Systems Engineering

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Stress concentration factors for multi-planar tubular KK-joints of jacket substructures in offshore wind turbines

  • Hamid Ahmadi (National Centre for Maritime Engineering and Hydrodynamics, Australian Maritime College, University of Tasmania) ;
  • Adel Alizadeh Atalo (Faculty of Civil Engineering, University of Tabriz)
  • Received : 2024.05.23
  • Accepted : 2024.09.10
  • Published : 2024.09.25
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Abstract

Although the investigation on the effect of loaded out-of-plane braces on the values of the stress concentration factor (SCF) in offshore tubular joints has been the objective of numerous research works, a number of quite important cases still exist that have not been studied thoroughly due to the diversity of joint types and loading conditions. One of these cases is the multi-planar tubular KK-joint subjected to axial loading. Tubular KK-joints are among the most common joint types in jacket substructure of offshore wind turbines (OWTs). In the present research, data extracted from the stress analysis of 243 finite element (FE) models, verified against available experimental data, was used to study the effects of geometrical parameters on the chord-side SCFs in multi-planar tubular KK-joints subjected to axial loading. Parametric FE study was followed by a set of nonlinear regression analyses to develop three new SCF parametric equations for the fatigue analysis and design of axially loaded multi-planar KK-joints.

Keywords

Acknowledgement

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

References

  1. Ahmadi, H. and Ghaffari, A. (2015), "Probabilistic analysis of stress intensity factor (SIF) and degree of bending (DoB) in axially loaded tubular K-joints of offshore structures", Lat. Am. J. Solids Struct., 12(11), 202-2044. https://doi.org/10.1590/1679-78251698.
  2. 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.
  3. 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.
  4. Ahmadi, H., Lotfollahi-Yaghin, M.A. and Aminfar, M.H. (2011a), "Distribution of weld toe stress concentration factors on the central brace in two-planar CHS DKT-connections of steel offshore structures", Thin-Wall. Struct., 49, 1225-1236. https://doi.org/10.1016/j.tws.2011.06.001.
  5. Ahmadi, H., Lotfollahi-Yaghin, M.A. and Aminfar, M.H. (2011b), "Effect of stress concentration factors on the structural integrity assessment of multi-planar offshore tubular DKT-joints based on the fracture mechanics fatigue reliability approach", Ocean Eng., 38, 1883-1893. https://doi.org/10.1016/j.oceaneng.2011.08.004.
  6. Ahmadi, H., Lotfollahi-Yaghin, M.A. and Aminfar, M.H. (2011c), "Geometrical effect on SCF distribution in uni-planar tubular DKT-joints under axial loads", J. Constr. Steel Res., 67(8), 1282-1291. https://doi.org/10.1016/j.jcsr.2011.03.011.
  7. Ahmadi, H., Lotfollahi-Yaghin, M.A. and Aminfar, M.H. (2012a), "The development of fatigue design formulas for the outer brace SCFs in offshore three-planar tubular KT-joints", Thin-Wall. Struct., 58, 67-78. https://doi.org/10.1016/j.tws.2012.04.011.
  8. Ahmadi, H., Lotfollahi-Yaghin, M.A., Shao, Y.B. and Aminfar, M.H. (2012b), "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.
  9. Ahmadi, H., Lotfollahi-Yaghin, M.A. and Shao, Y.B. (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. and Lotfollahi-Yaghin, M.A. (2012a), "A probability distribution model for stress concentration factors in multi-planar tubular DKT-joints of steel offshore structures", Appl. Ocean Res., 34, 21-32. https://doi.org/10.1016/j.apor.2011.11.002.
  11. Ahmadi, H. and Lotfollahi-Yaghin, M.A. (2013), "Effect of SCFs on S-N based fatigue reliability of multiplanar tubular DKT-joints of offshore jacket-type structures", Ships Offshore Struct., 8, 55-72. https://doi.org/10.1080/17445302.2011.627750.
  12. Ahmadi, H. and Lotfollahi-Yaghin, M.A. (2012b), "Geometrically parametric study of central brace SCFs in offshore three-planar tubular KT-joints", J. Constr. Steel Res., 71, 149-161. https://doi.org/10.1016/j.jcsr.2011.10.024.
  13. Ahmadi, H. and Lotfollahi-Yaghin, M.A. (2015), "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.
  14. Ahmadi, H. and Mousavi Nejad Benam, M.A. (2017), "Probabilistic analysis of SCFs in unstiffened gap tubular KT-joints of jacket structures under the OPB moment loads", Adv. Struct. Eng., 20, 595-615. https://doi.org/10.1177%2F1369433216658487. https://doi.org/10.1177%2F1369433216658487
  15. 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.
  16. 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.
  17. Ahmadi, H. (2016), "A probability distribution model for SCFs in internally ring-stiffened tubular KT-joints of offshore structures subjected to out-of-plane bending loads", Ocean Eng., 116, 184-199. https://doi.org/10.1016/j.oceaneng.2016.02.037.
  18. Ahmadi, H., Mohammadi, A.H., Yeganeh, A. and Zavvar, E. (2016), "Probabilistic analysis of stress concentration factors in tubular KT-joints reinforced with internal ring stiffeners under in-plane bending loads", Thin-Wall. Struct., 99, 58-75. https://doi.org/10.1016/j.tws.2015.11.010.
  19. Ahmadi, H., Mohammadi, A.H. and Yeganeh, A. (2015), "Probability density functions of SCFs in internally ring-stiffened tubular KT-joints of offshore structures subjected to axial load", Thin-Wall. Struct., 94, 485-499. https://doi.org/10.1016/j.tws.2015.05.012.
  20. American Petroleum Institute (API) (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.
  21. American Welding Society (AWS) (2002), Structural welding code: AWS D 1.1. Miami (FL), US.
  22. 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. httpd://doi.org/10.12989/ose.2014.4.2.151.
  23. Bomel Consulting Engineers (1994), "Assessment of SCF equations using Shell/KSEPL finite element data", C5970R02.01 REV C, Bomel Consulting Engineers.
  24. Cao, J.J., Yang, G.J. and Packer, J.A. (1997), "FE mesh generation for circular tubular joints with or without cracks", Proceedings of the 7th International Offshore and Polar Engineering Conference, Honolulu (HI), US.
  25. 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.
  26. Chang, E. and Dover, W.D. (1999b), "Prediction of stress distributions along the intersection of tubular Y and T-joints", Int. J. Fatigue, 21, 361-381. https://doi.org/10.1016/S0142-1123(98)00083-8.
  27. Chang, E. and Dover, W.D. (1996), "Stress concentration factor parametric equations for tubular X and DT joints", Int. J. Fatigue, 18(6), 363-387. https://doi.org/10.1016/0142-1123(96)00017-5.
  28. Chiew, S.P., Soh, C.K. and Wu, N.W. (1999), "Experimental and numerical stress analyses of tubular XT-joint", J. Struct. Eng.,125, 1239-1248. https://doi.org/10.1061/(ASCE)0733-9445(1999)125:11(1239).
  29. Chiew, S.P., Soh, C.K. and Wu, N.W. (2000), "General SCF design equations for steel multiplanar tubular XX-joints", Int. J. Fatigue, 22, 283-293. https://doi.org/10.1016/S0142-1123(99)00130-9.
  30. Efthymiou, M. and Durkin, S. (1985), "Stress concentrations in T/Y and gap/overlap K-joints", Proceedings of the Conference on Behavior of Offshore Structures, Delft, the Netherlands.
  31. Efthymiou, M. (1988), "Development of SCF formulae and generalized influence functions for use in fatigue analysis", OTJ 88, Surrey, UK.
  32. 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. Constr. Steel Res., 63, 305-316. https://doi.org/10.1016/j.jcsr.2006.05.007.
  33. Gao, F. (2006), "Stress and strain concentrations of completely overlapped tubular joints under lap brace OPB load", Thin-Wall. Struct., 44, 861-871, https://doi.org/10.1016/j.tws.2006.08.017.
  34. Gaspar, B., Garbatov, Y. and Guedes Soares, C. (2011), "Effect of weld shape imperfections on the structural hot-spot stress distribution", Ships Offshore Struct., 6(1-2), 145-159. https://doi.org/10.1080/17445302.2010.497052.
  35. Gho, W.M. and Gao, F. (2004), "Parametric equations for stress concentration factors in completely overlapped tubular K(N)-joints", J. Constr. Steel Res., 60, 1761-1782. https://doi.org/10.1016/j.jcsr.2004.05.003.
  36. 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/10.1016/0142-1123(90)90338-F.
  37. Hoon, K.H., Wong, L.K. and Soh, A.K. (2001), "Experimental investigation of a doubler-plate reinforced tubular T-joint subjected to combined loadings", J. Constr. Steel Res., 57, 1015-1039. https://doi.org/10.1016/S0143-974X(01)00023-2.
  38. IIW-XV-E (1999), Recommended fatigue design procedure for welded hollow section joints, IIW Docs, XV1035-99/XIII-1804-99. International Institute of Welding, France.
  39. Karamanos, S.A., Romeijn, A. and Wardenier, J. (2002), "SCF equations in multi-planar welded tubular DTjoints including bending effects", Mar. Struct., 15, 157-173, https://doi.org/10.1016/S0951-8339(01)00020-X.
  40. Karamanos, S.A., Romeijn, A. and Wardenier, J. (1999), "Stress concentrations in multi-planar welded CHS XX-connections", J. Constr. Steel Res., 50, 259-282.https://doi.org/10.1016/S0143-974X(98)00244-2.
  41. Karamanos, S.A., Romeijn, A. and Wardenier, J. (2000), "Stress concentrations in tubular gap K-joints: mechanics and fatigue design", Eng. Struct., 22, 4-14, https://doi.org/10.1016/S0141-0296(98)00062-5.
  42. Kuang, J.G., Potvin, A.B. and Leick, R.D. (1975), "Stress concentration in tubular joints", Proceedings of the Offshore Technology Conference, Paper OTC 2205, Houston (TX), US.
  43. Lee, M.K. and Wilmshurst, S.R. (1995), "Numerical modeling of CHS joints with multiplanar double-K configuration", J. Constr. Steel Res., 32, 281-301. https://doi.org/10.1016/0143-974X(95)93899-F.
  44. Lee, M.M.K. (1999), "Strength, stress and fracture analyses of offshore tubular joints using finite elements", J. Constr. Steel Res., 51, 265-286. https://doi.org/10.1016/S0143-974X(99)00025-5.
  45. Liu, G., Zhao, X. and Huang, Y. (2015), "Prediction of stress distribution along the intersection of tubular Tjoints by a novel structural stress approach", Int. J. Fatigue, 80, 216-230. https://doi.org/10.1016/j.ijfatigue.2015.05.021.
  46. 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.
  47. Lotfollahi-Yaghin, M.A. and Ahmadi, H. (2011), "Geometric stress distribution along the weld toe of the outer brace in two-planar tubular DKT-joints: parametric study and deriving the SCF design equations", Mar. Struct., 24, 239-260. https://doi.org/10.1016/j.marstruc.2011.02.005.
  48. 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.
  49. Morgan, M.R. and Lee, M.M.K. (1998b), "Prediction of stress concentrations and degrees of bending in axially loaded tubular K-joints", J. Constr. Steel Res., 45(1), 67-97. https://doi.org/10.1016/S0143-974X(97)00059-X.
  50. Myers, P.T., Brennan, F.P. and Dover, W.D. (2001), "The effect of rack/rib plate on the stress concentration factors in jack-up chords", Mar. Struct., 14, 485-505. https://doi.org/10.1016/S0951-8339(00)00051-4.
  51. N'Diaye, A., Hariri, S., Pluvinage, G. and Azari, Z. (2007), "Stress concentration factor analysis for notched welded tubular T-joints", Int. J. Fatigue, 29, 1554-1570. https://doi.org/10.1016/j.ijfatigue.2006.10.030.
  52. Nassiraei, H. and Chavoshi, H.R. (2024), "Collar plate effect on local joint flexibility of tubular K-joints under IPB moments: Parametric study and predictive equations", Mar. Struct., 98, 103676. https://doi.org/10.1016/j.marstruc.2024.103676.
  53. Nassiraei, H. (2022), "Geometrical effects on the LJF of tubular T/Y-joints with doubler plate in offshore wind turbines", Ships Offshore Struct., 17, 481-491. https://doi.org/10.1080/17445302.2020.1835051.
  54. Nassiraei, H. (2020), "Local joint flexibility of CHS T/Y-connections strengthened with collar plate under in-plane bending load: Parametric study of geometrical effects and design formulation", Ocean Eng., 202, 107054. https://doi.org/10.1016/j.oceaneng.2020.107054.
  55. Nassiraei, H. (2019a), "Local joint flexibility of CHS X-joints reinforced with collar plates in jacket structures subjected to axial load", Appl. Ocean Res., 93, 101961. https://doi.org/10.1016/j.apor.2019.101961.
  56. Nassiraei, H. (2024a), "Probabilistic analysis of strength in retrofitted X-joints under tensile loading and fire conditions", Building, 14, 2105. https://doi.org/10.3390/buildings14072105.
  57. Nassiraei, H. (2024b), "Probability distribution functions for the ultimate strength of X-joints with collar plates in compressive load at room and fire conditions", Struct., 59, 105703. https://doi.org/10.1016/j.istruc.2023.105703.
  58. Nassiraei, H. (2023), "Probability distribution models for the ultimate strength of tubular T/Y-joints reinforced with collar plates at room and different fire conditions", Ocean Eng., 270, 113557. https://doi.org/10.1016/j.oceaneng.2022.113557.
  59. 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.
  60. Nassiraei, H. and Rezadoost, P. (2021b), "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.
  61. 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.
  62. Nassiraei, H. (2019b), "Static strength of tubular T/Y-joints reinforced with collar plates at fire induced elevated temperature", Mar. Struct., 67, 102635. https://doi.org/10.1016/j.marstruc.2019.102635.
  63. Nassiraei, H. and Yara, A. (2022a), "Local joint flexibility of tubular K-joints reinforced with external plates under IPB loads", Mar. Struct., 84, 103199. https://doi.org/10.1016/j.marstruc.2022.103199.
  64. Nassiraei, H. and Yara, A. (2023), "Local joint flexibility of tubular K-joints reinforced with external plates under out of plane bending moments", Ships Offshore Struct., 18, 1688-1700. https://doi.org/10.1080/17445302.2022.2140508.
  65. Nassiraei, H. and Yara, A. (2022b), "Numerical analysis of local joint flexibility of K-joints with external plates under axial loads in offshore tubular structures", J. Mar. Sci. Appl., 21, 134-144. https://doi.org/10.1007/s11804-022-00302-w.
  66. Nwosu, D.I., Swamidas, A.S.J. and Munaswamy, K. (1995), "Numerical stress analysis of internal ring-stiffened tubular T-joints", J. Offshore Mech. Arct., 117, 113-125. https://doi.org/10.1115/1.2827061.
  67. 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.
  68. 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. Constr. Steel Res., 65, 2011-2026. https://doi.org/10.1016/j.jcsr.2009.05.004.
  69. Shao, Y.B. (2004a), "Fatigue behaviour of uni-planar CHS gap K-joints under axial and in-plane bending loads", Ph.D. Dissertation, School of Civil & Environmental Engineering, Nanyang Technological University, Singapore.
  70. Shao, Y.B. (2007), "Geometrical effect on the stress distribution along weld toe for tubular T- and K-joints under axial loading", J. Constr. Steel Res., 63, 1351-1360. https://doi.org/10.1016/j.jcsr.2006.12.005.
  71. Shao, Y.B. (2004b), "Proposed equations of stress concentration factor (SCF) for gap tubular K-joints subjected to bending load", Int. J. Space Struct., 19, 137-147. https://doi.org/10.1260%2F0266351042886667. https://doi.org/10.1260%2F0266351042886667
  72. Smedley, P. and Fisher, P. (1991), "Stress concentration factors for simple tubular joints", Proceedings of the International Offshore and Polar Engineering Conference (ISOPE), Edinburgh.
  73. UK Department of Energy (DoE) (1983), "Background notes to the fatigue guidance of offshore tubular joints", UK DoE, London, UK.
  74. UK Health and Safety Executive (HSE) (1997), "OTH 354: Stress concentration factors for simple tubular joints - assessment of existing and development of new parametric formulae", UK HSE, London, UK.
  75. Underwater Engineering Group (UEG) (1985), "Design of tubular joints for offshore structures", UEG/CIRIA, London (UK).
  76. Wingerde, A.M., Packer, J.A. and Wardenier, J. (2001), "Simplified SCF formulae and graphs for CHS and RHS K- and KK-connections", J. Constr. Steel Res., 57, 221-252. https://doi.org/10.1016/S0143-974X(00)00015-8.
  77. Woghiren, C.O. and Brennan, F.P. (2009), "Weld toe stress concentrations in multi planar stiffened tubular KK Joints", Int. J. Fatigue, 31, 164-172. https://doi.org/10.1016/j.ijfatigue.2008.03.039.
  78. Xu, F., Chen, J. and Jin, W. (2015), "Experimental investigation of SCF distribution for thin-walled concrete-filled CHS joints under axial tension loading", Thin-Wall. Struct., 93, 149-157. https://doi.org/10.1016/j.tws.2015.03.019.
  79. Yang, J., Chen, Y. and Hu, K. (2015), "Stress concentration factors of negative large eccentricity tubular N-joints under axial compressive loading in vertical brace", Thin-Wall. Struct., 96, 359-371. https://doi.org/10.1016/j.tws.2015.08.027.
  80. Zhao, X.L., Herion, S., Packer, J.A., Puthli, R., Sedlacek, G. and Wardenier, J. (2000), "Design guide for circular and rectangular hollow section joints under fatigue loading", CIDECT Publication, No. 8, TUV Verlag, Germany.