scholarly journals Analysis of tubular joint of offshore structure

2020 ◽  
Vol 1716 ◽  
pp. 012012
Author(s):  
Sanket Santosh Sawant ◽  
K. Dr. Muthumani
Keyword(s):  
Offshore Structure ◽  
Tubular Joint

scholarly journals Stress Concentration Factor of A Two-Planar Double KT Tubular Joint due to In-Plane Bending Loading in Steel Offshore Structures

2018 ◽  
Vol 177 ◽  
pp. 01006
Author(s):  
Prastianto Rudi Walujo ◽  
Hadiwidodo Yoyok Setyo ◽  
Fuadi Ibnu Fasyin
Keyword(s):  
Finite Element ◽  
Stress Concentration ◽  
Stress Concentration Factor ◽  
Concentration Factor ◽  
Element Model ◽  
Offshore Structures ◽  
Geometrical Parameters ◽  
Offshore Structure ◽  
Wide Range ◽  
Tubular Joint

The purpose of this study is to investigate the proper Stress Concentration Factor (SCF) of a 60° two-planar DKT tubular joint of a tripod wellhead offshore structure. So far, calculation of SCF for a multi-plane tubular joint was based on the formulation for the simple/uniplanar tubular joints that yield in over/under prediction of the SCF of the joint. This situation in turn decreasing the accuracy of fatigue life prediction of the structures. The SCF is one of the most important parameters in the tubular joint fatigue analysis. The tubular joint is modelled as finite element models with bending loads acting on the braces that cover a wide range of dimensionless geometrical parameters (β, τ, γ). The effect of such parameters on the SCF distribution along the weld toe of braces and chord on the joint are investigated. Validation of the finite element model has shown good agreement to the global structural analysis results. The results of parametric studies show that the peak SCF mostly occurs at around crown 2 point of the outer central brace. The increase of the β leads to decrease the SCF. While the increase of the τ and γ leads to increase the SCF. The effect of parameter β and γ on the SCF are greater than the effect of parameter τ.

Stresses in Stiffened Tubular T Joint of an Offshore Structure

1983 ◽  
Vol 105 (2) ◽  
pp. 177-183 ◽  
Author(s):  
M. R. Shiyekar ◽  
M. Kalani ◽  
R. M. Belkune
Keyword(s):  
Finite Element ◽  
Axial Loading ◽  
Offshore Structures ◽  
Internal Ring ◽  
Joint Models ◽  
Offshore Structure ◽  
T Joints ◽  
Tubular Joint ◽  
Simplified Analysis ◽  
Element Technique

The effect of internal ring stiffeners has been studied theoretically and experimentally for the welded tubular T joints occurring in conventional jacket-type offshore structures. Four welded tubular joint models of T shape, with different diameter ratios, have been tested under axial loading in the branch. The analytical results have been obtained by finite element technique. The results indicate a significant reduction in the stress concentration factor and a fairly uniform transfer of load from branch to the chord. A simplified analysis of stiffener rings have been proposed. The stress results of joints strengthened by ring stiffeners and joint can are compared.

The effect of shot peening on fatigue life of welded tubular joint in offshore structure

2012 ◽  
Vol 36 ◽  
pp. 250-257 ◽  
Author(s):  
N. Habibi ◽  
S.M. H-Gangaraj ◽  
G.H. Farrahi ◽  
G.H. Majzoobi ◽  
A.H. Mahmoudi ◽  
...  
Keyword(s):  
Fatigue Life ◽  
Shot Peening ◽  
Offshore Structure ◽  
Tubular Joint

Efficient Fatigue Testing of Tubular Joints

2015 ◽  
Author(s):  
P. Thibaux ◽  
J. Van Wittenberghe ◽  
E. Van Pottelberg ◽  
M. Van Poucke ◽  
P. De Baets ◽  
...  
Keyword(s):  
Finite Element ◽  
Fatigue Testing ◽  
Fatigue Loading ◽  
Tubular Joints ◽  
Testing Method ◽  
Out Of Plane ◽  
Resonance Principle ◽  
Tubular Joint ◽  
The Cost ◽  
Good Agreement

Tubular joints are intensively used in off-shore structures for shallow waters. Depending on the sea conditions and the type of structure, the design can be fatigue driven. This is particularly the case for off-shore wind turbines, where turbulences are generating a fatigue loading. Any improvement of the fatigue performance of the tubular joint would be beneficial to reduce the weight and the cost of the structure. To assess efficiently the fatigue resistance of the tubular joint, a testing method has been developed based on the resonance principle. The complete circumference of the welded joint can be loaded, successively in the in-plane and out-of-plane modes at a frequency close to 20Hz. Finite element computations were used to investigate the feasibility of the concept. Then, an X-node was made and successfully tested to investigate the stress distribution along the weld. The experimental results were compared with finite element computations, giving a good agreement.

A Parametric Study of Low-Frequency Damping of Mooring System

2014 ◽  
Author(s):  
Minglu Chen ◽  
Shan Huang ◽  
Nigel Baltrop ◽  
Ji Chunyan ◽  
Liangbi Li
Keyword(s):  
Low Frequency ◽  
Structure Design ◽  
The Body ◽  
Body Motion ◽  
Mooring Line ◽  
Offshore Structure ◽  
Frequency Oscillation ◽  
Low Frequency Oscillation ◽  
Line System ◽  
Irregular Wave

Mooring line damping plays an important role to the body motion of moored floating platforms. Meanwhile, it can also make contributions to optimize the mooring line system. Accurate assessment of mooring line damping is thus an essential issue for offshore structure design. However, it is difficult to determine the mooring line damping based on theoretical methods. This study considers the parameters which have impact on mooring-induced damping. In the paper, applying Morison formula to calculate the drag and initial force on the mooring line, its dynamic response is computed in the time domain. The energy dissipation of the mooring line due to the viscosity was used to calculate mooring-induced damping. A mooring line is performed with low-frequency oscillation only, the low-frequency oscillation superimposed with regular and irregular wave-frequency motions. In addition, the influences of current velocity, mooring line pretension and different water depths are taken into account.

A New Spectral Method for Modeling Dynamic Ice Actions

2004 ◽  
Author(s):  
Tuomo Ka¨rna¨ ◽  
Yan Qu ◽  
Walter L. Ku¨hnlein
Keyword(s):  
Dynamic Response ◽  
Spectral Density ◽  
Time Correlation ◽  
General Purpose ◽  
Density Functions ◽  
Offshore Structure ◽  
Spectral Density Functions ◽  
Ice Force ◽  
Ice Forces ◽  
Scale Data

This paper presents a method of evaluating the response of a vertical offshore structure that is subjected to dynamic ice actions. The model concerns a loading scenario where a uniform ice sheet is drifting and crushing against the structure. Full scale data obtained at the lighthouse Norstro¨msgrund is used in the derivation of a method that applies both to narrow and wide structures. A large amount of events with directly measured local forces was used to derive formulas for spectral density functions of the ice force. A non-dimensional formula that was derived for the autospectrum applies for all ice thicknesses. Coherence functions are used to define the cross-spectra of the local ice forces. The two kind of spectral density functions for local forces can be used to evaluate the spectral density of the total ice force. The method takes account of both the spatial and time correlation between the local forces. Accordingly, the model provides a tool to consider the non-simultaneous characteristics of the local ice pressures while assessing the total ice force. The model can be used in conjunction with general purpose FE programs to evaluate the dynamic response of an offshore structure.

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