Fatigue tests and design of CFRP-strengthened CHS gap K-joints

Lewei Tong, Guowen Xu, Xiao Ling Zhao, Yang Yan

Research output: Journal article publicationJournal articleAcademic researchpeer-review

18 Citations (Scopus)


This paper presents an experimental study on the fatigue behaviour of circular hollow section (CHS) gap K-joints strengthened by carbon fibre-reinforced polymer (CFRP) sheets (CFRP-CHS K-joint). Eight CFRP-CHS K-joints and three reference un-strengthened CHS gap K-joints were tested under cyclic axial loading. Fatigue failure modes of the CFRP-strengthened and un-strengthened joints were determined and compared. Fatigue lives in three fatigue failure criteria were recorded: crack-initiation fatigue N2, through-thickness fatigue N3, and end-of-test fatigue N4. The comparisons indicate that CFRP-CHS K-joints have a longer fatigue life than un-strengthened joints in the same nominal stress range, regardless of fatigue failure criteria (N2, N3, or N4). The increase in N3 was approximately 138%, on average. No significant difference in fatigue data in terms of hot spot stress range was found between the CFRP-strengthened and un-strengthened joints. Based on the experimental fatigue data, a modified Sr,hs-N curve based on the CIDECT recommended curve was proposed for CFRP-CHS K-joints.

Original languageEnglish
Article number107694
JournalThin-Walled Structures
Publication statusPublished - Jun 2021
Externally publishedYes


  • Carbon fibre-reinforced polymer
  • CFRP strengthening
  • Circular hollow section gap K-joint
  • Fatigue test
  • S–N curve

ASJC Scopus subject areas

  • Civil and Structural Engineering
  • Building and Construction
  • Mechanical Engineering


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