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; Aminfar, Mohammad H.

doi:10.1016/j.tws.2011.06.001

Cited by 35 publications

(15 citation statements)

References 23 publications

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“…Zavvar [24] for SCF design formulae and multiplanarity in KT-joints. As nonoverlapped tubular joints [2] are easy to fabricate and numerous techniques have been developed for assessing their strength and fatigue performances [4,5,[8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24], they are widely used in the construction of many tubular structures. However, when the brace-to-chord diameter ratio (β) is bigger than 0.6, nonoverlapped tubular joints may not be easily designed due to the limited range of geometric validity in many design codes [25,26].…”

Section: Advances In Civil Engineeringmentioning

confidence: 99%

“…us, the parametric formulae of uniplanar tubular joints for SCF prediction may not be suitable for such multiplanar connections. Due to the complexity and high cost involved, however, there have been much fewer research efforts on multiplanar tubular joints, such as Karamanos et al [15] and Chiew et al [16] for SCF parametric equations in XX-joints; Karamanos et al [17,18] and Jiang et al [19] for SCF prediction in DT-joints under axial and bending loads, respectively; van Wingerde et al [20] and Woghiren and Brennan [21] for SCF determination in KK-joints; and Ahmadi et al [22], Ahmadi et al [23], and Ahmadi and…”

Section: Introductionmentioning

confidence: 99%

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A Bracket‐Stiffened Two‐Planar Overlapped Tubular KT‐Joint for Offshore Jack‐Up Fatigue Analysis

Jian

Yue

Qiu

et al. 2021

Advances in Civil Engineering

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There have been a large number of research programs dedicated to the investigation of stress concentration factor and its parametric design formulae for a variety of uniplanar and multiplanar tubular joints. However, for the multiplanar overlapped tubular joints, the related reports are very limited due to the fact that the combining effect between multiplanarity and brace overlapping is quite complex. In this paper, a novel bracket-stiffened two-planar overlapped tubular KT-joint is proposed by adding two brackets between the upper diagonal and horizontal braces to alleviate the stress concentration at the brace-to-chord intersection area. As compared with the original KT-joint and KT-joint of larger brace gap, stress concentration reduction and fatigue strength enhancement at the most critical point of the proposed KT-joint are significant under both axial and in-plane bending (IPB) loads. The superiority of the proposed KT-joint is further tested with a simplified fatigue life assessment of offshore jack-up in field transit condition, when the KT-joint corresponding to the upper guide level is most critical and fatigue-sensitive. The obtained results with conservative assumptions may serve as guides or references in civil and offshore engineering practices.

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Section: Advances In Civil Engineeringmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

A Bracket‐Stiffened Two‐Planar Overlapped Tubular KT‐Joint for Offshore Jack‐Up Fatigue Analysis

Jian

Yue

Qiu

et al. 2021

Advances in Civil Engineering

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“…For multi-planar joints, the reader is referred to Karamanos et al (1999) and Chiew et al (2000) (for the SCF calculation in XX-joints); Wingerde et al (2001) (for the SCF determination in KK-joints); Karamanos et al (2002) (for the study of SCFs in DTjoints); Lotfollahi-Yaghin and Ahmadi (2011), Ahmadi et al (2011a, and Ahmadi and Lotfollahi-Yaghin (2012b) (for the comprehensive investigation of SCFs in two-and three-planar tubular KT-joints), among others. Dharmavasan and Aaghaakouchak (1988) indicated that in the case of axial and OPB loadings, careful positioning of the stiffeners considerably reduces the stress concentrations and gives a more uniform stress distribution along the brace/chord intersection.…”

Section: Deterministic Analysis Of Scfsmentioning

confidence: 99%

Probabilistic analysis of stress concentration factors in unstiffened gap tubular KT-joints of jacket structures under the out-of-plane bending moment loads

Ahmadi

Benam

2016

Advances in Structural Engineering

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The stress concentration factor, which is one of the primary input parameters for the fatigue reliability analysis of tubular joints commonly found in offshore jacket structures, shows substantial scatter that highlights the importance of accurate derivation of its governing probability function. In this article, results of 144 finite element stress analyses, validated using experimental data, were used to derive the probability density functions for the stress concentration factors in unstiffened gap tubular KT-joints under four types of out-of-plane bending moment loadings. Based on a parametric finite element study, a sample database was prepared for the maximum chord-side stress concentration factors of central and outer braces, and density histograms were generated for these samples. Nine different probability density functions were fitted to these histograms. The maximum likelihood method was used to estimate the parameters of fitted distributions. In each case, Kolmogorov–Smirnov test was applied to assess the goodness-of-fit. Finally, the inverse Gaussian model was selected as the best-fitted distribution, and after substituting the values of estimated parameters, six fully defined probability density functions were proposed for the maximum chord-side stress concentration factors of central and outer braces in unstiffened gap KT-joints under four types of out-of-plane bending loading.

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“…For multi-planar joints, the reader is referred to [28,29] (for the SCF calculation in XX-joints), [30] (for the SCF determination in KK-joints), [31] (for the study of SCFs in DT-joints), and [32][33][34][35] (for the comprehensive investigation of SCFs in two-and threeplanar tubular KT-joints), among others.…”

Section: Stress Concentration Factors In Unstiffened Tubular Jointsmentioning

confidence: 99%

Probability density functions of SCFs in internally ring-stiffened tubular KT-joints of offshore structures subjected to axial loading

Ahmadi

Mohammadi

Yeganeh

2015

Thin-Walled Structures

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Distribution of weld toe stress concentration factors on the central brace in two-planar CHS DKT-connections of steel offshore structures

Cited by 35 publications

References 23 publications

A Bracket‐Stiffened Two‐Planar Overlapped Tubular KT‐Joint for Offshore Jack‐Up Fatigue Analysis

A Bracket‐Stiffened Two‐Planar Overlapped Tubular KT‐Joint for Offshore Jack‐Up Fatigue Analysis

Probabilistic analysis of stress concentration factors in unstiffened gap tubular KT-joints of jacket structures under the out-of-plane bending moment loads

Probability density functions of SCFs in internally ring-stiffened tubular KT-joints of offshore structures subjected to axial loading

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