Influence of Elevated Temperatures on the Bond Behaviour of Sand-Coated and Ribbed GFRP Rebars In Concrete - Pull-Out Tests and Calibration of Temperature-Dependent Bond Stress vs. Slip Laws


Rosa I. C. , Firmo J. P. , Correia J. R. , Mazzuca P.

10th International Conference on Fibre-Reinforced Polymer (FRP) Composites in Civil Engineering (CICE), İstanbul, Turkey, 8 - 10 December 2021, vol.198, pp.774-787 identifier identifier

  • Publication Type: Conference Paper / Full Text
  • Volume: 198
  • Doi Number: 10.1007/978-3-030-88166-5_67
  • City: İstanbul
  • Country: Turkey
  • Page Numbers: pp.774-787
  • Keywords: GFRP rebars, Elevated temperatures, Bond, Concrete, Bond stress-slip laws, BARS, CFRP
  • Istanbul Technical University Affiliated: No

Abstract

This paper presents experimental and numerical investigations on the bond between concrete and GFRP rebars at moderately elevated temperatures. Pull-out tests were performed on sand-coated and two types of ribbed rebars, embedded in concrete cylinders, from room temperature up to 300 degrees C. The specimens were first heated up to the predefined temperature (measured at the rebarconcrete interface) and then loaded up to failure. The applied load and the slip of the rebars at their free and loaded ends were measured during the tests. The results confirmed that both the bond strength and stiffness suffer significant reductions with temperature, and that the surface finishing and glass transition temperature of the rebars are determinant factors governing the GFRP-concrete interaction at elevated temperatures. Most of the bond strength of the ribbed rebars was degraded up to 250 degrees C (well above the rebars' T-g), while in the sand coated rebars, such level of degradation occurred even before the T-g was attained. Using the experimental data obtained from the pull-out tests, local bond stress vs. slip laws were numerically calibrated considering the reduction of the bond strength, bond stiffness and elastic modulus of the rebars caused by increasing temperatures.