Stress concentration factors of CFRP-reinforced tubular K-joints via Zero Point Structural Stress Approach

Mohamed, Hazem Samih; Zhang, L.; Shao, Yongbo; Yang, X.S.; Shaheen, M.A.; Suleiman, M.F.

doi:10.1016/j.marstruc.2022.103239

Cited by 9 publications

(3 citation statements)

References 38 publications

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“…The diameter ratio of brace-to-chord β, the chord radius-to-thickness ratio γ, the thickness ratio of brace-to-chord τ, and the brace-to-chord angle θ have significant effects on the hot spot SCF of CHS K-joints, according to previous research [20,35].…”

Section: Generalmentioning

confidence: 63%

Stress Concentration Factors of Concrete-Filled Double-Skin Tubular K-Joints

Xia,

Ma,

et al. 2024

Buildings

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Tubular joints are important connecting parts of a welded steel tube structure. The S-N curves based on the hot spot stress (HSS) method are often used to evaluate the fatigue life of tubular joints in practical engineering. The stress concentration factor (SCF) is a key parameter to calculate HSS. In this paper, stress concentration tests of hollow-section and concrete-filled double-skin tubular (CFDST) K-joints were carried out, respectively, and then finite element models of K-joints considering the weld were established. The developed models were validated with the experimental results. The influence of key geometrical parameters, such as the diameter ratio of brace to chord β, the diameter to thickness ratio of chord γ, the wall thickness ratio of brace to chord τ, brace angle θ, and hollow section ratio ζ on the distribution and key position of SCFs along the weld toe, was discussed. Parametric studies were conducted to obtain the calculating equations for the SCF values of CFDST K-joints. The results demonstrate that infill concrete can effectively reduce SCFs along the weld on the chord. When the hollow section ratio was reduced to 0.317, the SCF was reduced by 77.2%. Notably, the SCF reduction rate was sensitive to γ and θ, with a decrease observed as γ increased. The hollow section ratio ζ had a less pronounced effect on SCF distribution patterns, but as ζ decreased, the chord’s stiffness improved, suggesting a potential approach to enhance joint performance. The distribution of SCFs is similar for joints of the same type but different geometric configurations. The innovatively integrated hollow section ratio in the CFDST design equation significantly simplifies and enhances the precision of SCF calculations for CFDST K-joints.

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Section: Generalmentioning

confidence: 63%

Stress Concentration Factors of Concrete-Filled Double-Skin Tubular K-Joints

Xia,

Ma,

et al. 2024

Buildings

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“…The basic principle of the fatigue performance of the welded structure reinforced with CFRP is to change the force transmission path of the original structure, such that part of the load is borne by CFRP, thereby reducing the stress state of the reinforced part. Research results have shown that CFRP can effectively reduce the SCF at the weld toe, which decreases significantly with the increase in the number of carbon cloth layers [22]. As shown in Figure 3a, taking account of the symmetry of WHSJs, only one-eighth of the tubespherical joints were analyzed, where the vertical boundaries of the sphere and the tube surface were fixed constraints.…”

Section: Scf Of Cfrp-strengthened Whsjmentioning

confidence: 99%

“…In studies on the fatigue performance of welding structures reinforced by CFRP, the test objects included butt joints in steel plates [12][13][14][15], cruciform welded joints [16][17][18][19], square pipe butt joints [20], K-shaped [21,22] and T-shaped [23] tube joints, and welded H-beams [24][25][26], which were characterized by a thick parent metal, relatively few weld defects, and an easy reinforcement operation. As shown in Table 1, the use of CFRP paste reinforcement could double the fatigue life or fatigue strength of components, and the reinforcement effect is remarkable.…”

Section: Introductionmentioning

confidence: 99%

Experimental Study on Fatigue Performance of Welded Hollow Spherical Joints Reinforced by CFRP

2022

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The risk of fatigue failure of welded hollow spherical joints (WHSJs) under alternating loads increases due to the inherent defects, the disrepair, and the demand for tonnage upgrades, of suspension cranes. The finite element analysis results revealed that the ranking of the stress concentration factor at the WHSJ was as follows: weld toe in steel tube of tube–ball connection weld > weld toe in steel tube of tube–endplate connection weld > weld toe in sphere of tube–ball connection weld > weld toe in plate of tube–endplate connection weld. Moreover, the peak stress at the weld of the tube–sphere connection was reduced by 32.93% after CFRP bonding reinforcement, which was beneficial for improving the fatigue performance. In this study, 16 full-scale specimens of Q235B WHSJs were tested by an MTS fatigue testing machine to study the strengthening effect of CFRP on the fatigue performance. It was found that the fatigue fracture of WHSJs was transferred from the tube–sphere connection weld to the tube–endplate connection after CFRP reinforcement. According to the fitted S-N curves, the fatigue strength could be increased by 13.26%–18.19% when the cycle number increased from 10,000 to 5,000,000.

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