On factors affecting CFRP-steel bonded joints

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21 Citations (Scopus)


Failure of structural steel members strengthened with Carbon Fibre Reinforced Polymers (CFRP) may occur at the joints CFRP-steel and this study examines variables that alter or explain the corresponding reduction of load capacity for a specific CFRP laminate, adhesive and steel. Factors and parameters likely to be influential like surface treatment prior to bonding, the bonded length, the glass transition temperature (Tg) of the adhesive, the exposure to aggressive environment, the temperature at service and different types of loading were examined. The experimental program selected double strap CFRP-steel bonded joints under shear for the analysis. The steel surfaces to be bonded were subjected to sand blasting (6.3 bar) or abrasive grinding (6.9 bar) corresponding to thorough blast cleaning Sa2; surfaces rusted after exposure to salt fog at 35 °C were also considered. Differences detected in responses of specimens treated by sand or steel spheres blasting were relatively minor. Tests made at increasing ambient temperatures confirmed that service temperature near and above adhesive Tg caused rapid deterioration of ultimate capacity and change of failure modes. Salt fog cycles (SF) originated the most significant losses of joint capacity. Application of cyclic static loading above the critical loading threshold obtained for unaged joints did not reduce the capacity of joints previously aged by freeze-thaw. The same cyclic loading after salt fog cycles, reduced bond capacity and increase the ultimate slip, suggesting larger effective length. Despite the losses of capacity, microscopic changes of structural nature could not be identified.

Original languageEnglish
Pages (from-to)360-375
Number of pages16
JournalConstruction and Building Materials
Publication statusPublished - 30 Nov 2019
Event9th International Conference on Fibre-Reinforced Polymer (FRP) Composites in Civil Engineering, CICE 2018 - Paris, France
Duration: 17 Jul 201819 Jul 2018


  • Adhesion
  • Bond-slip
  • CFRP-steel joints
  • Environmental degradation
  • Surface treatment
  • Thermal effects


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