Bond Performance of CFRP/Steel Double Strap Joint at Elevated Temperatures

Carbon fiber-reinforced polymer (CFRP) has been used widely in the strengthening of steel structures. Steel/CFRP systems being subjected to elevated temperatures is realistic in summer climate events in many countries, which leads to the degradation of the bond performance between CFRP and steel. Therefore, it is critical to study the bond behavior of the CFRP/steel system under elevated temperature. This paper investigates the mechanical performance of CFRP/steel adhesively bonded double strap joints under different temperatures. Thirty CFRP/steel double strap joints were tested to failure under temperatures between 10 °C and 90 °C. It was found that the joint failure mode changed from adherend failure to debonding failure as the temperature was approaching glass transition temperatures. In addition, the ultimate load and joint stiffness decreased significantly under temperatures near to and higher than glass transition temperatures. Based on the experimental results, a model is proposed to predict the bond stress of the CFRP/steel under different temperatures.