Stress concentration factors at saddle and crown positions on the central brace of two-planar welded CHS DKT-connections
Hamid Ahmadi , Mohammad Ali Lotfollahi-Yaghin , Mohammad H. Aminfar
Journal of Marine Science and Application ›› 2012, Vol. 11 ›› Issue (1) : 83 -97.
Stress concentration factors at saddle and crown positions on the central brace of two-planar welded CHS DKT-connections
A set of parametric stress analyses was carried out for two-planar tubular DKT-joints under different axial loading conditions. The analysis results were used to present general remarks on the effects of the geometrical parameters on stress concentration factors (SCFs) at the inner saddle, outer saddle, and crown positions on the central brace. Based on results of finite element (FE) analysis and through nonlinear regression analysis, a new set of SCF parametric equations was established for fatigue design purposes. An assessment study of equations was conducted against the experimental data and original SCF database. The satisfaction of acceptance criteria proposed by the UK Department of Energy (UK DoE) was also checked. Results of parametric study showed that highly remarkable differences exist between the SCF values in a multi-planar DKT-joint and the corresponding SCFs in an equivalent uni-planar KT-joint having the same geometrical properties. It can be clearly concluded from this observation that using the equations proposed for uni-planar KT-connections to compute the SCFs in multi-planar DKT-joints will lead to either considerably under-predicting or over-predicting results. Hence, it is necessary to develop SCF formulae specially designed for multi-planar DKT-joints. Good results of equation assessment according to UK DoE acceptance criteria, high values of correlation coefficients, and the satisfactory agreement between the predictions of the proposed equations and the experimental data guarantee the accuracy of the equations. Therefore, the developed equations can be reliably used for fatigue design of offshore structures.
offshore jacket structure / multi-planar tubular DKT-joint / fatigue / hot-spot stress method / stress concentration factor (SCF)
| [1] |
|
| [2] |
Ahmadi H, Lotfollahi-Yaghin MA (2008). Geometrical effect on the stress distribution along the weld toe for tubular KT-joints under balanced axial loading. Proceeding of the 8th International Conference on Coasts, Ports and Marine Structures (ICOPMAS), Tehran, Iran. |
| [3] |
|
| [4] |
|
| [5] |
|
| [6] |
|
| [7] |
Department of Energy Background notes to the fatigue guidance of offshore tubular joints, 1983, London, UK: HMSO |
| [8] |
Efthymiou M (1988). Development of SCF formulae and generalized influence functions for use in fatigue analysis. Offshore Tubular Joints Conference, Surrey, UK. |
| [9] |
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. |
| [10] |
|
| [11] |
|
| [12] |
|
| [13] |
|
| [14] |
IIW-XV-E Recommended fatigue design procedure for welded hollow section joints, 1999, Paris, France: International Institute of Welding |
| [15] |
|
| [16] |
|
| [17] |
|
| [18] |
Kuang JG, Potvin AB, Leick RD (1975). Stress concentration in tubular joints. Offshore Technology Conference, Houston, Texas, USA, Paper OTC 2205. |
| [19] |
|
| [20] |
|
| [21] |
|
| [22] |
|
| [23] |
Lotfollahi-Yaghin MA, Ahmadi H (2009). Numerical parametric study of stress concentration along the intersection of tubular KT-joints subjected to balanced axial loading. Proceedings of the 19th International Offshore and Polar Engineering Conference (ISOPE), Osaka, Japan. |
| [24] |
|
| [25] |
|
| [26] |
|
| [27] |
|
| [28] |
|
| [29] |
|
| [30] |
|
| [31] |
Smedley P, Fisher P (1991). Stress concentration factors for simple tubular joints. Proceedings of the International Offshore and Polar Engineering Conference, Edinburgh, Scotland. |
| [32] |
UK HealthSafety Executive Stress concentration factors for tubular complex joints, 1992, UK: Lloyd’s Register of Shipping |
| [33] |
UK HealthSafety Executive Stress concentration factors for simple tubular joints-assessment of existing and development of new parametric formulae, 1997, London, UK: Lloyd’s Register of Shipping |
| [34] |
|
| [35] |
|
| [36] |
Wordsworth AC (1981). Stress concentration factors at K and KT tubular joint. Proceedings of the Conference on Fatigue of Offshore Structural Steels, London, UK, 59–69. |
| [37] |
Wordsworth AC, Smedley GP (1978). Stress concentrations at unstiffened tubular joints. Proceedings of the European Offshore Steels Research Seminar, Cambridge, UK, Paper 31. |
| [38] |
|
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| 〈 |
|
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