Numerical analysis and formulae for SCF reduction coefficients of CFRP-strengthened CHS gap K-joints

Guowen Xu, Lewei Tong, Xiao Ling Zhao, Haiming Zhou, Fei Xu

Research output: Journal article publicationJournal articleAcademic researchpeer-review

24 Citations (Scopus)


The focus of this paper is on estimating stress concentration factor (SCF) reduction coefficients (ψ) of circular hollow section (CHS) gap K-joints strengthened with carbon fibre reinforced polymer (CFRP) sheets (CFRP-CHS K-joints), so that the SCFs can be calculated on the basis of the existing formulae for unstrengthened joints. Three-dimensional finite element models are developed for both CFRP-strengthened and unstrengthened CHS gap K-joints to calculate the SCFs, which are verified using previous test data. A parametric study is then carried out to explore the effects of various parameters (11 independent CFRP strengthening parameters and 5 basic geometric parameters describing the steel K-joints) on the efficiency of CFRP strengthening in terms of SCF reduction coefficient ψ. It is found that ψ is primarily affected by the CFRP relative reinforcement rates, the CFRP-to-steel tensile modulus ratios, the adhesive modulus, and non-dimensional geometric parameters. Through regression analyses, parametric formulae are finally developed for estimating ψ at six critical hot spots in CFRP-CHS K-joints under balanced axial loading. The proposed parametric formulae agree well with the experimental data.

Original languageEnglish
Article number110369
JournalEngineering Structures
Publication statusPublished - 1 May 2020
Externally publishedYes


  • Carbon fibre reinforced polymer
  • CFRP strengthening
  • Circular hollow section gap K-joint
  • Finite element analysis
  • Parametric formulae
  • SCF reduction coefficient

ASJC Scopus subject areas

  • Civil and Structural Engineering


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