A probability distribution model for stress concentration factors in multi-planar tubular DKT-joints of steel offshore structures

Article

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
Article Title

A probability distribution model for stress concentration factors in multi-planar tubular DKT-joints of steel offshore structures

ERA Journal ID22096
Article CategoryArticle
AuthorsAhmadi, Hamid and Lotfollahi-Yaghin, Mohammad Ali
Journal TitleApplied Ocean Research
Journal Citation34, pp. 21-32
Number of Pages12
YearJan 2012
PublisherElsevier
Place of PublicationUnited Kingdom
ISSN0141-1187
1879-1549
Digital Object Identifier (DOI)https://doi.org/10.1016/j.apor.2011.11.002
Web Address (URL)https://sciencedirect.com/science/article/pii/S0141118711000885
Abstract

The stress concentration factor (SCF) is one of the most important parameters in the fatigue reliability analysis of steel offshore structures. This parameter exhibits considerable scatter which calls for greater emphasis in accurately computing the SCFs for predicting the fatigue life of these structures. As far as the authors are aware, no comprehensive research has been carried out on the probability distribution of SCFs in tubular joints, especially multi-planar ones, which cover the majority of practical applications. What has been used so far as the probability distribution of SCFs in the reliability analysis of offshore structures is mainly based on assumptions and limited observations, especially in terms of distribution parameters. In the present paper, results of performing FE analysis on 81 steel multi-planar tubular DKT-joints have been used to propose a probability distribution model for SCFs along the weld toe of the central brace under axial loads. Based on the multi-planar DKT-joint FE models which are verified against experimental results and the predictions of Lloyd's Register (LR) equations, a set of SCF sample databases was constructed. 15 different probability density functions (PDFs) were fitted to the relative frequency histograms of the SCF samples. The maximum likelihood method was used to determine the parameters of each distribution. Standard goodness-of-fit tests led to the conclusion that the Inverse Gaussian distribution is the best probability model for the peripheral distribution of SCFs along the weld toe and the Birnbaum–Saunders distribution is the best one for the maximum value of weld toe SCF.

KeywordsOffshore jacket structure; Fatigue reliability; Multi-planar tubular DKT-joint; Stress concentration factor (SCF); Probability density function (PDF); Goodness-of-fit test
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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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
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
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
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
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.