Stress concentration factors and fatigue behavior of square bird-beak SHS T-joints under out-of-plane bending

2015 ◽  
Vol 99 ◽  
pp. 677-684 ◽  
Author(s):  
Bin Cheng ◽  
Qin Qian ◽  
Xiao-Ling Zhao
Keyword(s):  
Stress Concentration ◽  
Fatigue Behavior ◽  
T Joints ◽  
Bird Beak ◽  
Out Of Plane ◽  
Concentration Factors ◽  
Plane Bending ◽  
Stress Concentration Factors

STRESS CONCENTRATION FACTORS AND FATIGUE FAILURE OF WELDED T-CONNECTIONS IN CIRCULAR HOLLOW SECTIONS UNDER IN-PLANE BENDING

2004 ◽  
Vol 04 (03) ◽  
pp. 403-422 ◽  
Author(s):  
FIDELIS RUTENDO MASHIRI ◽  
XIAO-LING ZHAO ◽  
PAUL GRUNDY
Keyword(s):  
Stress Concentration ◽  
Failure Criterion ◽  
Fatigue Behavior ◽  
Design Guidelines ◽  
T Joints ◽  
Fatigue Design ◽  
Concentration Factors ◽  
Thin Walled ◽  
Plane Bending ◽  
Stress Concentration Factors

The fatigue behavior of welded thin-walled T-joints made up of both circular hollow section (CHS) braces and chords, subjected to cyclic in-plane bending, is described in this paper. CHS chords and braces are of thicknesses less than 4 mm. Current fatigue design guidelines show that the design of welded tubular nodal joints is restricted to thicknesses greater than or equal to 4 mm. The increased availability and use of thin-walled (t<4 mm) tubes of high-strength steels in recent years, in structures subjected to cyclic loading, means that it is important to study the fatigue behavior of welded thin-walled tubular nodal joints. In this paper, welded thin-walled CHS-CHS T-joints subjected to constant-stress-amplitude cyclic in-plane bending range are studied. The stress concentration factors (SCFs) determined experimentally at the brace and chord crown positions are shown to be about 30% and 40% respectively of the SCFs determined using parametric equations in existing fatigue design guidelines. The fatigue tests showed that in welded thin-walled CHS-CHS T-joints, a through-thickness crack occurs when the surface crack length along the weld toes in the chord has grown to a length equal to about 40% of the circumference of the brace member. An end of test failure criterion was proposed as an alternative to the through-thickness failure criterion, in obtaining data that is suitable for determining fatigue design S-N curves.

Stress concentration factors of diamond bird-beak SHS T-joints under brace loading

2014 ◽  
Vol 74 ◽  
pp. 201-212 ◽  
Author(s):  
Lewei Tong ◽  
Yuguang Fu ◽  
Yongqiang Liu ◽  
Xiao-Ling Zhao
Keyword(s):  
Stress Concentration ◽  
T Joints ◽  
Bird Beak ◽  
Concentration Factors ◽  
Stress Concentration Factors

Stress Concentrations in DT/X Square-to-Square and Square-to-Round Tubular Joints

1994 ◽  
Vol 116 (2) ◽  
pp. 49-55 ◽  
Author(s):  
A. K. Soh ◽  
C. K. Soh
Keyword(s):  
Stress Concentration ◽  
Bending Moment ◽  
Bending Moments ◽  
Axial Loads ◽  
Stress Concentrations ◽  
Tubular Joints ◽  
Out Of Plane ◽  
Concentration Factors ◽  
Plane Bending ◽  
Stress Concentration Factors

A parametric stress analysis of DT/X square-to-square and square-to-round tubular joints subjected to axial loads, in-plane, and out-of-plane bending moments has been performed using the finite element technique in order to provide a sound basis for using such sections in the design of complex structures. The results of this analysis are presented as a set of equations expressing the stress concentration factor as a function of the relevant geometric parameters for various loading conditions. A comparison is made between the results obtained for square-to-square and square-to-round tubular joints and those obtained for round-to-round tubular joints by other researchers. In general, the stress concentration factors for square-to-square tubular joints are the highest, followed by those of the corresponding round-to-round joints, with those of the corresponding square-to-round joints the lowest when the joints are subject to axial loads. In the case of in-plane bending moment, the stress concentration factors for square-to-square joints are generally still the highest, but followed by those of the corresponding square-to-round joints, with those of the corresponding round-to-round joints the lowest. However, the stress concentration factors for the three types of joint are comparable when they are subject to out-of-plane bending moments.

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

2016 ◽  
Vol 20 (4) ◽  
pp. 595-615 ◽  
Author(s):  
Hamid Ahmadi ◽  
Mir Amin Mousavi Nezhad Benam
Keyword(s):  
Stress Concentration ◽  
Probability Density ◽  
Bending Moment ◽  
Probability Density Functions ◽  
Density Functions ◽  
Out Of Plane ◽  
Jacket Structures ◽  
Concentration Factors ◽  
Plane Bending ◽  
Stress Concentration Factors

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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