Stress concentration factors for non-90° X-connections made of square hollow sections

1998 ◽  
Vol 25 (2) ◽  
pp. 370-375 ◽  
Author(s):  
J A Packer ◽  
J Wardenier
Keyword(s):  
Stress Concentration ◽  
Strong Influence ◽  
Hot Spot ◽  
Steel Structures ◽  
Hot Spot Stress ◽  
Hollow Section ◽  
Measured Stress ◽  
Concentration Factors ◽  
Stress Concentration Factors ◽  
Hollow Structural Sections

A number of fatigue experiments and stress concentration factor measurements on non-90°, square hollow section X-connections have been carried out. Comparison of the measured stress concentration factors with those derived from existing parametric formulae for 90° T- and X-connections showed a strong influence of the brace angle. A tentative extension of the range of validity of the parametric formulae for 90° T- and X-connections for other brace angles has been derived.Key words: steel structures, connections, fatigue, hollow structural sections, hot spot stress, stress concentration factors.

Stress Distribution Formulas and Comparison of Three Stress Analysis Techniques for Tubular Joints

1985 ◽  
Vol 107 (1) ◽  
pp. 60-67
Author(s):  
S. Dharmavasan ◽  
W. D. Dover
Keyword(s):  
Stress Concentration ◽  
Stress Analysis ◽  
Mixed Mode ◽  
Hot Spot ◽  
Offshore Structures ◽  
Hot Spot Stress ◽  
Analysis Techniques ◽  
Mode Stress ◽  
Concentration Factors ◽  
Stress Concentration Factors

The available data on hot spot stress for tubular welded joints has been reviewed and a database established. Stress analysis techniques in general use for the design of offshore structures and parametric equations have been assessed against this database to determine their accuracy. A set of equations to predict the stress distributions for simple joints has been proposed and has been used to predict mixed mode stress concentration factors. Results obtained from a complex K joint have been examined in detail and the importance of the stress state, when predicting the mixed mode stress concentration factors, is demonstrated.

scholarly journals SCFs study of tubular T/Y steel joints under inplane loading

2019 ◽  
Vol 252 ◽  
pp. 06010
Author(s):  
Lalitesh Kumar ◽  
Ajay Kumar ◽  
Danuta Barnat-Hunek ◽  
Elżbieta Szczygielska ◽  
Monika Garbacz
Keyword(s):  
Stress Concentration ◽  
Hot Spot ◽  
Axial Loading ◽  
Geometrical Parameters ◽  
Fe Modelling ◽  
Element Analysis ◽  
Hot Spot Stress ◽  
Concentration Factors ◽  
Stress Concentration Factors ◽  
Steel Joints

Stress concentration factors (SCFs) at welded tubular joints are one of the prime factors that affect the fatigue life of a structure. In the present work, finite element analysis (FEA) is used to find the hot spot stress and subsequently the stress concentration factors of Tubular T/Y steel Joints. Static axial tensile loading case is used in the present work. The circular hollow sections (CHS) are considered. The parametric study of the variation in SCF, with the change in joint angle (ϴ) and geometrical parameters such as β, τ, γ for T/Y-Joints subjected to inplane axial loading, is done. The validation of FE modelling technique of present work is done by comparing with the various SCFs equations available in the literature

Experimental and numerical analysis of the stress concentration factor for concrete-filled square hollow section Y-joints

2019 ◽  
Vol 23 (5) ◽  
pp. 869-883
Author(s):  
Lei Jiang ◽  
Yongjian Liu ◽  
Jiang Liu ◽  
Bin Liu
Keyword(s):  
Finite Element ◽  
Stress Concentration ◽  
Parametric Design ◽  
Hot Spot ◽  
Design Parameters ◽  
Finite Element Models ◽  
Stress Concentrations ◽  
Hollow Section ◽  
Concentration Factors ◽  
Stress Concentration Factors

Previous studies have shown that the stress concentration factors for 90° square hollow section T- and X-joints can be significantly reduced by filling the chord with concrete and stiffening the chord with perfobond ribs. The current study examined stress concentration factors for non-90° (Y-type) joints. A total of 11 Y-joints were tested under axial tension, and the hot spot stresses were measured. The measured results were employed to evaluate the influence of design parameters on the stress concentrations. In addition, the measured results were used to evaluate finite element models. A parametric study was then undertaken using the finite element models to generate an extensive database of stress concentration factors and to develop parametric design equations to estimate the maximum stress concentration factors on the brace and the chord of concrete-filled square hollow section Y-joints with perfobond ribs. It was found that decreases of 13.7%–59.9% in the stress concentration factors occurred in concrete-filled square hollow section Y-joints stiffened by perfobond ribs relative to conventional square hollow section joints for different loading cases.

Stress Concentration Factors in Tubular K-Joints Under Combined Loadings

2010 ◽  
Author(s):  
Tuanhai Chen ◽  
Guoming Chen
Keyword(s):  
Stress Concentration ◽  
Boundary Conditions ◽  
Hot Spot ◽  
Offshore Platforms ◽  
Stress Distributions ◽  
Hot Spot Stress ◽  
Loading Effects ◽  
Concentration Factors ◽  
Stress Concentration Factors ◽  
Combined Loadings

A numerical method of stress concentration factors (SCFs) in tubular K-joints under combined loadings was proposed, and the loading effects on SCFs were investigated by using this method. Since it couldn’t present the state of stress concentration very well if the displacements were used as the boundary conditions, the load boundary conditions were selected to analyze the stress distribution of the tubular K-joints. In view of the disadvantages of the superposition of stress distributions from each uniaxial loading mode, an alternative method for the calculation of the hot spot stress under combined loadings was provided. In this method, three basic types of basic loadings namely, axial loading, in-plane and out-of-plane bending moments were applied to the tubular joints simultaneously by virtue of the submodeling technique in ANSYS system. Then the stress distributions along the intersection of tubular K-joints under combined loadings were developed directly, and the hot spot stresses were obtained through extrapolation. Finally, according to parametric study, the loading effects of ice thickness and drift direction on SCF distributions and values were studied through this method. The investigation provides the theoretical basis for determining SCF in tubular K-joints under different load cases in evaluating the ice-induced fatigue of offshore platforms, and has very important engineering application value.

Experimental, numerical and parametric studies on stress concentration factors of T-joints under tension

2021 ◽  
pp. 136943322110499
Author(s):  
Feleb Matti ◽  
Fidelis Mashiri
Keyword(s):  
Finite Element ◽  
Stress Concentration ◽  
Numerical Study ◽  
Hot Spot ◽  
Joint Models ◽  
Element Analysis ◽  
T Joints ◽  
Concentration Factors ◽  
Stress Concentration Factors ◽  
Good Agreement

This paper investigates the behaviour of square hollow section (SHS) T-joints under static axial tension for the determination of stress concentration factors (SCFs) at the hot spot locations. Five empty and corresponding concrete-filled SHS-SHS T-joint connections were tested experimentally and numerically. The experimental investigation was carried out by attaching strain gauges onto the SHS-SHS T-joint specimens. The numerical study was then conducted by developing three-dimensional finite element (FE) T-joint models using ABAQUS finite element analysis software for capturing the distribution of the SCFs at the hot spot locations. The results showed that there is a good agreement between the experimental and numerical SCFs. A series of formulae for the prediction of SCF in concrete-filled SHS T-joints under tension were proposed, and good agreement was achieved between the maximum SCFs in SHS T-joints calculated from FE T-joint models and those from the predicted formulae.

Stress Concentration Factors Calculation: Analytical and Numerical Approaches for Welded Tubular Joints

2020 ◽  
Author(s):  
Nathalia Paruolo ◽  
Thalita Mello ◽  
Paula Teixeira ◽  
Marco Pérez
Keyword(s):  
Stress Concentration ◽  
Oil And Gas ◽  
Hot Spot ◽  
Experimental Tests ◽  
Oil And Gas Industry ◽  
Offshore Structures ◽  
Gas Industry ◽  
Tubular Joints ◽  
Concentration Factors ◽  
Stress Concentration Factors

Abstract In the oil and gas industry, fixed platforms are commonly applied in shallow water production. In-place environmental conditions generates cyclic loads on the structure that might lead to structural degradation due to fatigue damage. Fatigue is one of the most common failure modes of offshore structures and is typically estimated when dimensioning of the structure during design phase. However, in times when life extension of existing offshore structures is being a topic in high demand by industry, mature fields may represent an interesting investment, especially for small companies. Concerning fixed platforms, composed mainly by welded tubular joints, the assessment of hot spot stresses is considered to predict structure fatigue. The estimation of welded joint hot spot stresses is based on the stress concentration factors (SCFs), which are given by parametric formulae, finite element analysis (FEA) or experimental tests. Parametric formulae may be defined as a fast and low-cost method, meanwhile finite elements analysis may be time consuming and experimental tests associated with higher costs. Given these different characteristics, each method is applied according to the study case, which will rely on the joint geometry and associated loads. Considering simple joint geometries several sets of parametric equations found in the literature may be applied. On the other hand, the SCFs calculation of non-studied yet complex joints consider known formulae adapted according to the under load joint behavior and geometry. Previous analysis shows that this adaptation may furnish different results compared to those obtained by FEA. Furthermore, it is observed that even for simple joints the results derived from the different methods may differ. Given their importance for the oil and gas industry, since they are the basis for the assessment of the fatigue life of welded tubular joints which may impact on additional costs related to maintenance and inspection campaigns, the estimation of SCFs must be the most accurate as possible. Therefore, this paper intends to investigate the differences between results derived from parametric formulae and different FEA studies.

A Multidimensional FEA Approach for Determination of Hot Spot Stresses in Offshore Jacket Structures

2021 ◽  
Author(s):  
Kris Hectors ◽  
Hasan Saeed ◽  
Wim De Waele
Keyword(s):  
Fatigue Life ◽  
Stress Concentration ◽  
Hot Spot ◽  
Wave Spectrum ◽  
Wave Direction ◽  
Tubular Joints ◽  
Jacket Structures ◽  
Concentration Factors ◽  
Stress Concentration Factors

Abstract A new fatigue lifetime assessment approach for offshore jacket structures is presented. It combines a previously developed numerical framework for automated determination of stress concentration factors in tubular joints and a multidimensional finite element modelling approach. The approach is explained based on a case study of an OC4 type offshore jacket. To determine the fatigue life, a directional wave spectrum is combined with the JONSWAP spectrum. The fatigue life of the jacket is assessed for two different sea states. Based on the fatigue analysis the most fatigue critical wave direction is identified. The hot spot stresses in one of the most critical joints are determined and compared to stresses obtained with the Efthymiou equations. The shortcomings of these equations are highlighted and it is shown how the numerical framework can be used to improve the current fatigue design philosophy for offshore jackets which relies on the Efthymiou equations for stress concentration factors in the welded tubular joints.

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