Abstract:
Carbon Fibre Reinforced Polymer (CFRP) is being used as a retrofitting material for
different structures such as, concrete and steel. Glass transition temperature (Tg) of the
bond between CFRP and steel influences on the service and fire performance of
strengthened members. A total of eighty-two CFRP/steel double strap joints were
prepared and tested under elevated temperature. They were cured under a range of
elevated temperature conditions in the control laboratory environment and in the
open environment which is practically feasible in large civil engineering structures.
The test results showed a similar trend of reductions in the bond strength, Poisson’s
ratio and Elastic modulus of CFRP/steel joint with the exposure to the elevated
temperature. More than 50% reduction in the Poisson’s ratio, elastic modulus and the
bond strength was noted when the bond line temperature exceeds Tg + 15 0C,
irrespective of the curing time and curing conditions. Initial elevated temperature
curing also causes for shifting the curves in the right-skewed direction. A significant
increase in Tg of bond was noted with 4 hours initial curing at 75 0C, i.e. Tg +20 0C.
Then a numerical model develops to predict the bond characteristics of CFRP/steel
composites cured under different curing conditions and their behaviour at elevated
temperatures. The measured material properties and their degradation with the
temperature exposure were considered. The predicted bond performance was in a
good agreement with the test results. The strain variation in the CFRP sheet was used
to develop the bond shear stress-slip variations. Parametric studies were also
conducted to evaluate the effects of bond line parameters on the bond shear stressslip
relationship at elevated temperature. The results indicate that the maximum bond
shear stress of the joint lies in the range between 25 MPa and 28 MPa at ambient
conditions, irrespective of the curing type. A rapid decrease in the maximum bond
shear stress appears with exposure to the elevated temperature. Maximum shear
stress reaches 10 MPa when the bond line temperature exceeds 90 0C. The elevated
temperature curing, exposed temperature during service and the bond thickness
notably affects on the bond slip behavior.
Citation:
Chandrathilaka, E.R.K. (2019). Bond performance of CFRP/Steel composite at elevated temperatures [Master’s theses, University of Moratuwa]. Institutional Repository University of Moratuwa. http://dl.lib.mrt.ac.lk/handle/123/15817