Impact of elevated temperature and anchored grooves on the shear behavior of reinforced concrete beams strengthened with CFRP composites

Exposure of concrete structures to elevated temperatures causes a severe deterioration because of decomposition of cement hydration products, generation of vapor pressure, and the inhomogeneous volume changes of concrete's ingredients and beyond a temperature of 500 °C. The most Retrieval the structural performance of severely heat-damaged structural concrete members would be most significantly achieved using carbon fiber-reinforced polymer (CFRP) composite materials. Nevertheless, debonding and anchoring problems remain a challenge for the success of this technique. In this study, an innovative application was implemented in which CFRP strips were integrated as external shear reinforcement for reinforced concrete (RC) beams by using the groove technique. The intent was to assess the CFRP strips' contribution to the shear strength and thus evaluate the effectiveness of using them as main or supplemental shear reinforcement before and after exposure to elevated temperature. The investigated parameters include the area and number of layers of CFRP strips and different elevated temperatures. By demonstrating an outstanding structural performance with significant enhancement in the ultimate strength, ultimate deflection, stiffness, and toughness, this paper's findings strongly attest that CFRP strips can be effectively utilized as external shear reinforcement in reinforced concrete beams exposed to elevated temperatures. New guideline and proposed empirical model are developed to predict the damage level and shear strength of heated damaged RC beams externally reinforced with CFRP composites considering the influence of the number of CFRP strips and elevated temperature as groove technique.