Analysis of Stress Concentration Factors due to in-Plane Bending and out-of-Plane Bending Loads on Tubular TY-Joints of Offshore Structures

Abstract

The aim of this work is to study the stress distributions and the location of hot spots stress in the vicinity of the intersection lines of the tubular elements of the tubular TY-joints. Using the finite element models, we analyze the effects of geometrical parameters on the stress concentration factor in the case of in-plane bending and out-of-plane bending loads, around the weld toe of the tubular joints. Our results reveal the location of the maximum stress concentration factor at the heel or toe in the case of in-plane bending loads and at the saddle point in the case of out-of-plane bending loads. Six parametric equations are established and used to calculate the stress concentration factor at critical locations using the non-linear regression method. The results obtained from the finite element analysis are close to the results of the parametric equations and the experimental data from the previous work.

Keywords

Offshore platform / Tubular TY-joint / Stress concentrations / Fatigue / In-plane bending / Out-of-plane bending

References

[1] Ahmadi H, Lotfollahi-Yaghin MA, Aminfar MH. Geometrical effect on SCF distribution in uni-planar tubular DKT-joints under axial loads. Journal of Constructional Steel Research, 2011, 67: 1282-1291

[2] Ahmadi H, Lotfollahi-Yaghin MA, Aminfar MH. 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 Engineering, 2011, 38: 1883-1893

[3] Ahmadi H, Lotfollahi-Yaghin MA, Aminfar MH. The development of fatigue design formulas for the outer brace SCFs in offshore three-planar tubular KT-joints. Thin-Walled Structures, 2012, 58: 67-78

[4] Ahmadi H, Lotfollahi-Yaghin MA. A probability distribution model for stress concentration factors in multi-planar tubular DKT-joints of steel offshore structures. Applied Ocean Research, 2012, 34: 21-32

[5] Ahmadi H, Lotfollahi-Yaghin MA, Shao YB, Aminfar MH. Parametric study and formulation of outer-brace geometric stress concentration factors in internally ring-stiffened tubular KT-joints of offshore structures. Applied Ocean Research, 2012, 38: 74-91

[6] Ahmadi H, Lotfollahi-Yaghin MA. Effect of SCFs on S—N based fatigue reliability of multi-planar tubular DKT-joints of offshore jacket-type structures. Ships and Offshore Structures, 2013, 8(1): 55-72

[7] Ahmadi H, Lotfollahi-yaghin MA. Stress concentration due to in-plane bending (IPB) loads in ring-stiffened tubular KT-joints of offshore structures: Parametric study and design formulation. Applied Ocean Research, 2015, 51: 54-66

[8] Ahmadi H, Zavvar E. Thin-Walled Structures Stress concentration factors induced by out-of-plane bending loads in ring-stiffened tubular KT-joints of jacket structures. Thin Walled Structure, 2015, 91: 82-95

[9] Ahmadi H, Mohammadi AH, Yeganeh A. Probability density functions of SCFs in internally ring-stiffened tubular KT-joints of offshore structures subjected to axial load. Thin-Walled Structures, 2015, 4: 485-499

[10] Ahmadi H, Mohammadi AH, Yeganeh A, Zavvar E. Probabilistic analysis of stress concentration factors in tubular KT-joints reinforced with internal ring stiffeners under in-plane bending loads. Thin-Walled Structures, 2016, 99: 58-75

[11] Ahmadi H. A probability distribution model for SCFs in internally ring-stiffened tubular KT-joints of offshore structures subjected to out-of-plane bending loads. Ocean Engineering, 2016, 116: 184-199

[12] Ahmadi H, Nejad AZ. Stress Concentration Factors in Uniplanar Tubular KT-Joints of Jacket Structures Subjected to In-Plane Bending Loads. International Journal of Maritime Technology, 2016, 5: 27-39

[13] Ansari MI, Ajay K. Bending analysis of functionally graded CNT reinforced doubly curved singly ruled truncated rhombic cone. Mechanics Based Design of Structures and Machines, 2018, 47: 67-86

[14] Ansari MI, Ajay K. Flexural analysis of functionally graded CNT reinforced doubly curved singly ruled composite truncated cone. Journal of Aerospace Engineering, 2019, 32(2): 040181541-0401815411

[15] API Recommended Practice for planning, Designing and constructing Fixed Offshore Platforms, 1993, 1st edn, Washignton DC: API RP2a- LRFD

[16] Arsem (1987) Design guides for offshore structures. Edition Technip, Paris

[17] AWS (2002) Structural welding code. AWS D 1.1; USA.

[18] Bellagh K (2001) Calcul du facteur de concentration de contraintes dans les jonctions tabulaires soudées soumises à des chargements combinés, Diplôme Magister En Génie Mécanique. Université de Mentouri Constantine (in French)

[19] Cao JJ, Yang GJ, Packer JA (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.

[20] Cao Y, Zhen Y, Liu C, Zhang S, Meng Z. Parametric study of stress concentration factors (CSFs) on tubular X-joints used in offshore platform structures. Journal of Coastal Research, 2018, 34(4): 987-995

[21] Chang E, Dover WD. Stress concentration factor parametric equations for tubular X and DT joints. International Journal of Fatigue, 1996, 18(6): 363-387

[22] Chang E, Dover WD. Parametric equations to predict stress distributions along the intersection of tubular X and DT-joints. Int J Fatigue, 1999, 21: 619-635

[23] DNVGL-RP-C203 (2016) Fatigue Design of Offshore Steel Structures, Oslo

[24] Efthymiou M, Durkin S (1985) Stress concentrations in T/Y and gap/overlap K-joints. Proceedings of the Conference on Behavior of Offshore Structures, Delft, Netherlands 429–440

[25] Efthymiou M (1988) Development of SCF formulae and generalized influence functions for use in fatigue analysis. OTJ 88, Surrey, UK

[26] Fricke W, Bollero A, Chirica I, Garbatov Y, Jancart F, Kahl A, Remes H, Rizzo CM, Selle HV, Urban A, Wei L. Round robin study on structural hot-spot and effective notch stress analysis. Ships and Offshore Structures, 2008, 3(4): 335-345

[27] Gao F. Stress and strain concentrations of completely overlapped tubular K(N) -joints under lap brace OPB load. Thin-Walled Structures, 2006, 44: 861-871

[28] Gao F, Shao YB, Gho WM. Stress and strain concentration factors of completely overlapped tubular K(N) -joints under lap brace IPB load. Journal of Constructional Steel Research, 2007, 63: 305-316

[29] Gandhi P, Ramachandra DS, Raghava G, Madhava Rao AG. Fatigue crack growth in stiffened steel tubular joints in seawater environment. Engineering Structures, 2000, 22: 1390-1401

[30] Hectors K, Waele WD. Influence of weld geometry on stress concentration factor distributions in tubular joints. Journal of Constructional Steel Research, 2021, 176: 1-15

[31] Hellier AK, Connolly MP, Dover WD. Stress concentration factors for tubular Y- and T-joints. International Journal of Fatigue, 1990, 12: 13-23

[32] Hoon KH, Wong LK, Soh AK. Experimental investigation of a doubler-plate reinforced tubular T-joint subjected to combined loadings. Journal of Constructional Steel Research, 2001, 57: 1015-1039

[33] Iberahin J. SCF Analysis of Tubular K-Joint under Compressive and Tensile Loads. SSRG International Journal of Mechanical Engineering, 2018, 5(10): 5-8

[34] Iberahin J, Talal SM. Tubular K-Joint under Out-of-plane Bending. SSRG Int. J. Mech. Eng., 2019, 6(4): 18-22

[35] IIW-XV-E Recommended fatigue design procedure for welded hollow section joints, 1999, France: International Institute of Welding, IIW Docs, XV-1035-99/XIII-1804-99

[36] Kuang JG, Potvin AB, Leick RD (1975) Stress concentration in tubular joints, Offshore Technology Conference. Paper OTC 2205, Houston, Texas

[37] Lalitesh K, Ajay K, Danuta BH, Przemysaw B (2018) SCFs study of Tubular T/Y, X-Joints under inplane loading, 3rd edition of International Conference of Computational Methods in Engineering Science (CMES’18). Poland, November, 22–24

[38] Lee MMK, Wilmshurst SR. Numerical modeling of CHS joints with multiplanar double-K configuration. Journal of Constructional Steel Research, 1995, 32: 281-301

[39] Lee MMK. Strength, stress and fracture analyses of offshore tubular joints using finite elements. Journal of Constructional Steel Research, 1999, 51(3): 265-286

[40] Liu G, Zhao X, Huang Y. Prediction of stress distribution along the intersection of tubular T-joints by a novel structural stress approach. International Journal of Fatigue, 2015, 80: 216-230

[41] Lloyd’s Register of Shipping (1992) Stress concentration factors for tubular. 71 Fenchurch Street London EC3M 4BS

[42] Lozano-Minguez E, Brennan FP, Kolios AJ. Reanalysis of offshore T-joint fatigue life predictions based on a complete weld profile model. Renewable Energy, 2014, 71: 486-494

[43] Mohamad FG (2007) Etude numérique et expérimentale des jonctions tubulaires soudées des plateformes offshore soumises à des sollicitations complexes, Thèse en Sciences des Matériaux. Université de Paul Verlaine Metz (in French)

[44] Morgan MR, Lee MMK. Prediction of stress concentrations and degrees of bending in axially loaded tubular K-joints. Journal of Constructional Steel Research, 1998, 45(1): 67-97

[45] Morgan MR, Lee MMK. Parametric equations for distributions of stress concentration factors in tubular K-joints under out-of-plane moment loading. International Journal of Fatigue, 1998, 20(6): 449-461

[46] N’Diaye A, Hariri S, Pluvinage G, Azari Z. Stress concentration factor analysis for notched welded tubular T-joints. International Journal of Fatigue, 2007, 29: 1554-1570

[47] Ravi K, Ajay K, Małgorzata S, Danuta BH, Joanna S. Axial and Shear Buckling Analysis of Multiscale FGM Carbon Nanotube Plates Using the MTSDT Model: A Numerical Approach. Materials, 2022, 15: 1-25

[48] Schürmann, Karsten W. Fatigue behavior of automatically welded tubular joints for offshore wind energy substructures, 2021, Hannover: Gottfried Wilhelm Leibniz Universität

[49] Shao YB. Proposed equations of stress concentration factor (SCF) for gap tubular K-joints subjected to bending load. International Journal of Space Structures, 2004, 19(3): 137-147

[50] Shao YB, Du ZF, Lie ST. Prediction of hot spot stress distribution for tubular K-joints under basic loadings. Journal of Constructional Steel Research, 2009, 65: 2011-2026

[51] Sambo MA, Kol GR, Betchewe G. Analysis of Geometrical Parameters of Tubular TY-Joints on Stress Concentration Factors Due to Axial Loads. Journal of Marine Science and Application, 2022, 21(2): 133-143

[52] Smedley P, Fisher P (1991) Stress concentration factors for simple tubular joints. Proceedings of the Int. Offshore and Polar Engineering Conference., ISOPE 91, Edinburgh, Scotland

[53] UK DoE (1995) Background to new fatigue design guidance for steel joints and connections in offshore structures. London, UK

[54] UK HSE, OTH 354 (1997) Stress Concentration Factors for Simple Tubular Joints-Assessment of Existing and Development of New Parametric Formulae. Prepared by Lloyd’s Register of Shipping, UK

[55] UK HSE, OTH 91 353 (1992) Stress concentration factors for tubular complex joints. Prepared by Lloyd’s Register of Shipping

[56] Vincent B. Calcul Des Soudures En Fatigue, 2011, France: Institut National des Sciences Appliquées de Toulouse, (in French)

[57] Visser W (1974) On the structural design of tubular joints. Offshore Technology Conference, OTC 2117, Houston, Texas

[58] Wordsworth AC (1981) Stress concentration factors at K and KT tubular joint. Proceedings of the Conference on Fatigue of Offshore Structural Steels 59–69

[59] Yang J, Chen Y, Hu K. Stress concentration factors of negative large eccentricity tubular N-joints under axial compressive loading in vertical brace. Thin-Walled Structures, 2015, 96: 359-371