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

Article

Lotfollahi-Yaghin, Mohammad Ali and Ahmadi, Hamid. 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." Marine Structures. 24 (3), pp. 239-260. https://doi.org/10.1016/j.marstruc.2011.02.005
Article Title

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

ERA Journal ID3795
Article CategoryArticle
AuthorsLotfollahi-Yaghin, Mohammad Ali and Ahmadi, Hamid
Journal TitleMarine Structures
Journal Citation24 (3), pp. 239-260
Number of Pages22
YearJul 2011
PublisherElsevier
Place of PublicationUnited Kingdom
ISSN0951-8339
1873-4170
Digital Object Identifier (DOI)https://doi.org/10.1016/j.marstruc.2011.02.005
Web Address (URL)https://www.sciencedirect.com/science/article/pii/S0951833911000098
Abstract

Regarding the research efforts expended so far on the calculation of stress concentration factors (SCFs) in tubular joints, two major shortcomings can be noted: (a) significant effort has been devoted to the study of SCFs in various uni-planar connections. Nevertheless, for multi-planar joints which cover the majority of practical applications, very few investigations have been reported due to the complexity and high cost involved; (b) majority of these research works focused on the study of SCFs at certain positions such as the saddle, crown toe, and crown heel, and they have ignored the hot-spot stress (HSS) at other positions along the weld toe. In the present paper, effects of dimensionless geometrical parameters on the SCF distribution along the weld toe of main (outer) braces in the axially loaded right-angle two-planar tubular DKT-joints are investigated. In order to study the multi-planar effect, SCF distribution in two-planar joints is compared with the distribution in a uni-planar joint having the same geometrical properties. A complete set of SCF database is constructed based on the two-planar DKT-joint Finite element models which are verified against experimental results and the predictions of Lloyd’s Register (LR) equations. The FE models cover a wide range of geometrical parameters. Six new SCF parametric formulae are developed through nonlinear regression analyses for the accurate and reliable fatigue design of two-planar DKT-joints under axial loads. An assessment study of these equations is conducted against the experimental data, the original FEM database and the acceptance criteria recommended by the UK Department of Energy.

KeywordsFatigue; Fracture mechanics; Stress concentration factor (SCF); SCF distribution; Multi-planar tubular DKT-joint; CHS connection
ANZSRC Field of Research 2020401504. Ship and platform structures (incl. maritime hydrodynamics)
400510. Structural engineering
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Byline AffiliationsUniversity of Tabriz, Iran
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Ahmadi, Hamid and Asoodeh, Shadi. 2016. "Parametric study of geometrical effects on the degree of bending (DoB) in offshore tubular K-joints under out-of-plane bending loads." Applied Ocean Research. 58, pp. 1-10. https://doi.org/10.1016/j.apor.2016.03.004
A probability distribution model for SCFs in internally ring-stiffened tubular KT-joints of offshore structures subjected to out-of-plane bending loads
Ahmadi, Hamid. 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 Engineering. 116, pp. 184-199. https://doi.org/10.1016/j.oceaneng.2016.02.037
Static strength of offshore tubular T/Y-joints reinforced with collar plate subjected to tensile brace loading
Nassiraei, Hossein, Lotfollahi-Yaghin, Mohammad Ali and Ahmadi, Hamid. 2016. "Static strength of offshore tubular T/Y-joints reinforced with collar plate subjected to tensile brace loading." Thin-Walled Structures. 103, pp. 141-156. https://doi.org/10.1016/j.tws.2016.02.010
Parametric Study on the Effects of Pile Inclination Angle on the Response of Batter Piles in Offshore Jacket Platforms
Aminfar, Ali, Ahmadi, Hamid and Aminfar, Mohammad Hossein. 2016. "Parametric Study on the Effects of Pile Inclination Angle on the Response of Batter Piles in Offshore Jacket Platforms." Journal of Marine Science and Application. 15, pp. 193-200. https://doi.org/10.1007/s11804-016-1355-9
Static strength of collar plate reinforced tubular T/Y-joints under brace compressive loading
Nassiraei, Hossein, Lotfollahi-Yaghin, Mohammad Ali and Ahmadi, Hamid. 2016. "Static strength of collar plate reinforced tubular T/Y-joints under brace compressive loading." Journal of Constructional Steel Research. 119, pp. 39-49. https://doi.org/10.1016/j.jcsr.2015.12.011
Probabilistic analysis of stress concentration factors in tubular KT-joints reinforced with internal ring stiffeners under in-plane bending loads
Ahmadi, Hamid, Yeganeh, Ali, Mohammadi, Amir Hossain and Zavvar, Esmaeil. 2016. "Probabilistic analysis of stress concentration factors in tubular KT-joints reinforced with internal ring stiffeners under in-plane bending loads." Thin-Walled Structures. 99, pp. 58-75. https://doi.org/10.1016/j.tws.2015.11.010
Comparing the geodetical and geotechnical methods in investigating the deformation of earthfill dams; A case study of Mahabad Earthfill Dam, Iran
Aminfar, M. H., Rastbud, A., Ahmadi, H. and Naseri, A.. 2016. "Comparing the geodetical and geotechnical methods in investigating the deformation of earthfill dams; A case study of Mahabad Earthfill Dam, Iran." Journal of Engineering Science and Technology. 11 (4), pp. 619-637.
Probability density functions of SCFs in internally ring-stiffened tubular KT-joints of offshore structures subjected to axial loading
Ahmadi, Hamid, Mohammadi, A. and Yeganeh, Ali. 2015. "Probability density functions of SCFs in internally ring-stiffened tubular KT-joints of offshore structures subjected to axial loading." Thin-Walled Structures. 94, pp. 485-499. https://doi.org/10.1016/j.tws.2015.05.012
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
Ahmadi, Hamid, Lotfollahi-Yaghin, Mohammad Ali and Asoodeh, Shadi. 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 Engineering. 102, pp. 105-116. https://doi.org/10.1016/j.oceaneng.2015.04.050
Stress concentration due to in-plane bending (IPB) loads in ring-stiffened tubular KT-joints of offshore structures: Parametric study and design formulation
Ahmadi, Hamid and Lotfollahi-Yaghin, Mohammad Ali. 2015. "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. 51, pp. 54-66. https://doi.org/10.1016/j.apor.2015.02.009
Stress concentration factors induced by out-of-plane bending loads in ring-stiffened tubular KT-joints of jacket structures
Ahmadi, Hamid and Zavvar, Esmaeil. 2015. "Stress concentration factors induced by out-of-plane bending loads in ring-stiffened tubular KT-joints of jacket structures." Thin-Walled Structures. 91, pp. 82-95. https://doi.org/10.1016/j.tws.2015.02.011
Probabilistic analysis of stress intensity factor (SIF) and degree of bending (DoB) in axially loaded tubular K-joints of offshore structures
Ahmadi, Hamid and Ghaffari, Amirreza. 2015. "Probabilistic analysis of stress intensity factor (SIF) and degree of bending (DoB) in axially loaded tubular K-joints of offshore structures." Latin American Journal of Solids and Structures. 12 (11), pp. 2025-2044. https://doi.org/10.1590/1679-78251698
Probabilistic Assessment of Degree of Bending in Tubular X-Joints of Offshore Structures Subjected to Bending Loads
Ahmadi, Hamid and Ghaffari, Amirreza. 2015. "Probabilistic Assessment of Degree of Bending in Tubular X-Joints of Offshore Structures Subjected to Bending Loads." Advances in Civil Engineering. 2015, pp. 1-13. https://doi.org/10.1155/2015/518450
Chord-side SCF distribution of central brace in internally ring-stiffened tubular KT-joints: A geometrically parametric study
Ahmadi, Hamid, Lotfollahi-Yaghin, Mohammad Ali and Yong-Bo, Shao. 2013. "Chord-side SCF distribution of central brace in internally ring-stiffened tubular KT-joints: A geometrically parametric study." Thin-Walled Structures. 70, pp. 93-105. https://doi.org/10.1016/j.tws.2013.04.011
Effect of SCFs on S-N based fatigue reliability of multi-planar tubular DKT-joints of offshore jacket-type structures
Ahmadi, Hamid and Lotfollahi-Yaghin, Mohammad Ali. 2013. "Effect of SCFs on S-N based fatigue reliability of multi-planar tubular DKT-joints of offshore jacket-type structures." Ships and Offshore Structures. 8 (1), pp. 55-72. https://doi.org/10.1080/17445302.2011.627750
Parametric study and formulation of outer-brace geometric stress concentration factors in internally ring-stiffened tubular KT-joints of offshore structures
Ahmadi, Hamid, Lotfollahi-Yaghin, Mohammad Ali, Yong-Bo, Shao and Aminfar, Mohammad H.. 2012. "Parametric study and formulation of outer-brace geometric stress concentration factors in internally ring-stiffened tubular KT-joints of offshore structures." Applied Ocean Research. 38, pp. 74-91. https://doi.org/10.1016/j.apor.2012.07.004
The development of fatigue design formulas for the outer brace SCFs in offshore three-planar tubular KT-joints
Ahmadi, Hamid, Lotfollahi-Yaghin, Mohammad Ali and Aminfar, Mohammad H.. 2012. "The development of fatigue design formulas for the outer brace SCFs in offshore three-planar tubular KT-joints." Thin-Walled Structures. 58, pp. 67-78. https://doi.org/10.1016/j.tws.2012.04.011
Slamming induced dynamic response of a floating structure
Lotfollahi-Yaghin, Mohammad Ali, Rastgar, Mehdi and Ahmadi, Hamid. 2012. "Slamming induced dynamic response of a floating structure." Journal of Marine Science and Technology (Taiwan). 20 (2), pp. 201-209. https://doi.org/10.51400/2709-6998.1839
A probability distribution model for stress concentration factors in multi-planar tubular DKT-joints of steel offshore structures
Ahmadi, Hamid and Lotfollahi-Yaghin, Mohammad Ali. 2012. "A probability distribution model for stress concentration factors in multi-planar tubular DKT-joints of steel offshore structures." Applied Ocean Research. 34, pp. 21-32. https://doi.org/10.1016/j.apor.2011.11.002
Geometrically parametric study of central brace SCFs in offshore three-planar tubular KT-joints
Ahmadi, Hamid and Lotfollahi-Yaghin, Mohammad Ali. 2012. "Geometrically parametric study of central brace SCFs in offshore three-planar tubular KT-joints." Journal of Constructional Steel Research. 71, pp. 149-161. https://doi.org/10.1016/j.jcsr.2011.10.024
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
Ahmadi, Hamid, Lotfollahi-Yaghin, Mohammad Ali and Aminfar, Mohammad H.. 2011. "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. 38 (17-18), pp. 1883-1893. https://doi.org/10.1016/j.oceaneng.2011.08.004
Distribution of weld toe stress concentration factors on the central brace in two-planar CHS DKT-connections of steel offshore structures
Ahmadi, Hamid, Lotfollahi-Yaghin, Mohammad Ali and Aminfar, Mohammad H.. 2011. "Distribution of weld toe stress concentration factors on the central brace in two-planar CHS DKT-connections of steel offshore structures." Thin-Walled Structures. 49 (10), pp. 1225-1236. https://doi.org/10.1016/j.tws.2011.06.001
Geometrical effect on SCF distribution in uni-planar tubular DKT-joints under axial loads
Ahmadi, Hamid, Lotfollahi-Yaghin, Mohammad Ali and Aminfar, Mohammad H.. 2011. "Geometrical effect on SCF distribution in uni-planar tubular DKT-joints under axial loads." Journal of Constructional Steel Research. 67 (8), pp. 1282-1291. https://doi.org/10.1016/j.jcsr.2011.03.011
Geometrical Parametric Study and Development of Design Formulae for the SCF Distribution Along the Weld Toe in Multi-Planar CHS DKT-Connections of Offshore Structures
Lotfollahi-Yaghin, Mohammad Ali, Ahmadi, Hamid and Shahverdi, Sajad. 2011. "Geometrical Parametric Study and Development of Design Formulae for the SCF Distribution Along the Weld Toe in Multi-Planar CHS DKT-Connections of Offshore Structures ." ASME 2011 30th International Conference on Ocean, Offshore and Arctic Engineering. Rotterdam, The Netherlands 19 - 24 Jun 2011 American Society of Mechanical Engineers (ASME). https://doi.org/10.1115/OMAE2011-49121
Effect of geometrical parameters on SCF distribution along the weld toe of tubular KT-joints under balanced axial loads
Lotfollahi-Yaghin, Mohammad Ali and Ahmadi, Hamid. 2010. "Effect of geometrical parameters on SCF distribution along the weld toe of tubular KT-joints under balanced axial loads." International Journal of Fatigue. 32 (4), pp. 703-719. https://doi.org/10.1016/j.ijfatigue.2009.10.008
Dynamic behaviour of damaged reinforced concrete beams and application of white noise analysis to crack detection
Lotfollahi-Yaghin, M.A., Shahinpar, R. and Ahmadi, H.. 2009. "Dynamic behaviour of damaged reinforced concrete beams and application of white noise analysis to crack detection." Journal of the South African Institution of Civil Engineering. 51 (2), pp. 2-10.