SHEAR BEHAVIOR OF HIGH STRENGTH CONCRETE BEAMS REINFORCED WITH GFRP BARS AND STRENGTHENED BY CFRP SHEETS

الملخص

This paper presents an experimental investigation on shear behavior of Glass Fiber Reinforced Polymer (GFRP) reinforced high strength concrete beams externally strengthened in shear using Carbon Fiber Reinforced Polymer (CFRP) with various configurations: full side sheets, U-strips, vertical side strips and diagonal side strips; and three steel fiber ratios (0%, 0.5% and 1%). Results show that using GFRP bars as tension reinforcement instead of traditional steel bars slightly increases ultimate load but shows lower stiffness. Although internal steel stirrups are still the most effective way to enhance shear capacity of concrete beams, externally bonded CFRP U-strips can also be an effective alternative for durability and/or architectural considerations with about 85% strength efficiency and comparable load-deflection behavior. A combination of U-strips and sufficient amount of steel fiber is shown to perform better than steel stirrups in terms of increasing carrying capacity and decreasing deflections of GFRP reinforced concrete beams.