Structural response of high strength concrete beams using fiber reinforced polymers under reversed cyclic loading

Abstract

This paper investigates the response of high strength concrete (HSC) beams subjected to reversed cyclic loading using carbon fiber-reinforced polymer (CFRP), glass fiber-reinforced polymers (GFRP), and hybrid FRP/steel bars as bottom tensile reinforcement. Five HSC beams with a rectangular cross-section were prepared and poured using with a 28-day concrete compressive strength of 60 MPa (8.7 ksi). A displacement-controlled reversed cyclic loading has been applied to all the beams. The test setup has been designed to represent seismic effect on structures. Flexural capacity, concrete and reinforcement steel strains, cracking behavior, and ductility results were obtained. The hybrid steel/FRP has shown an improved performance in terms of flexural capacity, strains, and ductility. While the inclusion of FRP grids reduces the flexural capacity, this can be improved by adding more layers of FRP. Overall, the nominal moment of the hybrid sections were the highest between all beams. The ACI 318 code’s empirical equations showed close results in terms of the tensile strength of the FRP. The ACI 440R has shown overestimated nominal moment values compared to the experimental results.