Fatigue behavior of bird-beak SHS X-joints under cyclic brace axial forces

Fenghua Huang, Bin Cheng, Chen Li, Xiao ling Zhao

Research output: Journal article publicationJournal articleAcademic researchpeer-review

8 Citations (Scopus)


This paper presents an experimental investigation on the fatigue behavior of bird-beak X-joints under brace axial force. Two square bird-beak and two diamond bird-beak specimens were fabricated by using 80% partial joint penetration (PJP) welds. Static loading was firstly carried out to measure the hot spot stresses at weld toes, by which stress concentration factors (SCFs) were extrapolated and subsequently the critical locations were identified. A cyclic axial loading was then implemented on the brace end. The fatigue behavior investigated includes crack initiation, crack propagation, failure mode, fatigue life and stiffness degradation. The results show that the SCFs calculated from test data could well predict the location of crack initiation. Furthermore, the through-thickness crack lives (N3) of all are found to be greater than the fatigue lives derived from the IIW (International Institute of Welding) design S[sbnd]N curves, which indicates that these curves for conventional joints can be conservatively used for estimating the fatigue life of bird-beak SHS X-joints.

Original languageEnglish
Article number106021
JournalJournal of Constructional Steel Research
Publication statusPublished - Jun 2020
Externally publishedYes


  • Bird-beak X-joint
  • Fatigue behavior
  • Fatigue test
  • Square hollow section (SHS)
  • Stress concentration factor

ASJC Scopus subject areas

  • Civil and Structural Engineering
  • Building and Construction
  • Mechanics of Materials
  • Metals and Alloys


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