PSI - Issue 64

Yuan Xu et al. / Procedia Structural Integrity 64 (2024) 1865–1872 Author name / Structural Integrity Procedia 00 (2019) 000–000

1872

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that CFRP layers exhibited similar effects on ψ with the CFRP width when the cross-sectional area of CFRP remained consistent. It was, therefore, suggested that the effect of the configuration of CFRP on the hot spot stress distribution of the T-joints could be ignored. 4. Conclusions This study presents a numerical study on SCFs of the chord-brace intersection area in the prestressed CFRP strengthened T-joints under axial loading. The models were verified by the experimental data. A parametric study was conducted to explore effects of CFRP strengthening parameters on the SCF reduction coefficients ψ . Based on the limited test results, the following observations can be made and conclusions drawn.  Introduction of prestress into CFRP strengthened T-joints changed the hot spot stress distribution and values along the weld toe. With the increase of prestress, the position of maximum stress gradually moves from saddle point to crown point.  Stress variation along the weld toe during CFRP prestressing and axial loading was investigated. In the CFRP prestressing stage, the stress linearly increased with increase of the prestress. In axial loading stage, the stress first decreased to offset the effect of prestressing, and then increased with the axial load.  Strengthening parameters including the prestressing level, CFRP layers and width had significant effects on the reduction of the hot spot stress along the weld toe. With increase of prestress, a noticeable reduction of hot spot stress was observed at each position, especially at the saddle point. Acknowledgements The authors wish to acknowledge the financial support of the National Natural Science Foundation of China (Grant No. 52222803), Shanghai Sailing Program (21YF1452400), CSCEC Technology R&D Program (CSCEC-2022-Z-8) and the Fundamental Research Funds for the Central Universities. References Choo, Y. S., Van der Vegte, G. J., Zettlemoyer, N., Li, B. H., Liew, J. Y. R., 2005. Static Strength of T-Joints Reinforced with Doubler or Collar Plates. I: Experimental Investigations. Journal of Structural Engineering 131(1), 119-128. Tong, L., Xu, G., Zhao, X. L., Zhou, H., Xu, F., 2019. Experimental and theoretical studies on reducing hot spot stress on CHS gap K-joints with CFRP strengthening. Engineering Structures 201, 109827. Hosseini, A. S., Bahaari, M. R., Lesani, M.,2020. Experimental and parametric studies of SCFs in FRP strengthened tubular T-joints under axially loaded brace. Engineering Structures 213, 110548. Nassiraei, H., Rezadoost, P., 2021a. Stress concentration factors in tubular X-connections retrofitted with FRP under compressive load. Ocean Engineering 229, 108562. Nassiraei, H., Rezadoost, P., 2021b. SCFs in tubular X-connections retrofitted with FRP under in-plane bending load. Composite Structures 274, 114314. Nassiraei, H., Rezadoost, P., 2021c. SCFs in tubular X-joints retrofitted with FRP under out-of-plane bending moment. Marine Structures 79, 103010. Xu, X., Shao, Y., Gao, X., Mohamed, H. S., 2022. Stress concentration factor (SCF) of CHS gap TT-joints reinforced with CFRP. Ocean Engineering 247, 110722. Tong, L., Xu, G., Zhao, X. L., Yan, Y., 2021. Fatigue tests and design of CFRP-strengthened CHS gap K-joints. Thin-Walled Structures 163, 107694. ANSI/AWS, D., 2020. Stuctural Welding Code — Steel. American Welding Society, Miami, America. Xu, G., Tong, L., Zhao, X. L., Zhou, H., Xu, F., 2020. Numerical analysis and formulae for SCF reduction coefficients of CFRP-strengthened CHS gap K-joints. Engineering Structures 210, 110369. Zhao, X. L., Packer, J. A., 2000. Recommended fatigue design procedure for welded hollow section joints. Abington Publishing, Cambridge. Zhao, X. L., Herion, S., Packer, J.A., Puthli, R. S., Sedlacek, G., Wardenier, J., Weynand, K., van Wingerde, A. M., Yeomans, N. F.,2001. Design guide for circular and rectangular hollow section joints under fatigue loading. CIDECT Design Guide No.8. TÜV-Verlag GmbH, Cologne, Germany. Department of Energy, 1998. Investigation into the differences between the measured hot-spot stress when derived by either linear or non-linear extrapolation techniques. Lloyd’s Register for the Den. Health and Safety Executive - Offshore Technology Report: Stress concentration factors for simple tubular joint, Lloyd’s Register of Shipping, 1997.