BENDING ANALYSIS OF RECYCLED CONCRETE BEAMS REINFORCED WITH GFRP BARS UNDER HIGH TEMPERATURE

GFRP (Fiber Reinforced Polymer) reinforcement material is characterized by high strength and excellent corrosion resistance, which exhibits promising application prospects in engineering. The GFRP reinforcement for steel-concrete beams can increase the structural load-bearing capacity and durability. In this study, a refined finite element model of hightemperature GFRP-reinforced recycled steel- concrete beams was established by using ABAQUS software. The temperature distribution and residual load-carrying capacity of GFRP-reinforced recycled steel-concrete beams were analyzed, and the reliability of the model was validated based on the results of full-scale experiments on 16 groups of recycled steel-concrete beams. By using the validated model, the influence of heating temperature, reinforcement strength, steel strength, strengthening method, and concrete strength on the residual load-carrying capacity of the structure was analyzed. The stress patterns and failure mechanisms of GFRP-reinforced recycled steel-concrete beams were also analyzed. As can be seen from the results, the Type II strengthening method significantly increased the load-carrying capacity of recycled steelconcrete beams. It was also found that the load-carrying capacity of the tested beams was greatly affected by temperature. Under the temperature of 200. and 600., the load- carrying capacity of the unreinforced specimens decreases by approximately 13% and around 25%, respectively. Under the same heating temperature, compared to the unreinforced specimens, the load-carrying capacity was increased by approximately 10% by using the Type I strengthening method, but only around 4.7% by the Type II strengthening method. Finally, based on the results of this study and existing relevant experimental and numerical simulation results, and considering its feasibility and effectiveness, the Type I strengthening method for reinforced recycled steel-concrete beams was proposed. In general, the research findings of this paper can provide theoretical support for the design of reinforced recycled steel-concrete beams.