FLEXURAL BEHAVIOR OF NORMAL AND HIGH STRENGTH CONTINUOUS BEAMS REINFORCED BY GFRP BARS

الملخص

In the reinforced concrete structures, fiber reinforced polymer (FRP) has been considered an alternative material to steel reinforcement with the advantages of corrosion resistance, non-conductivity, and high strength to weight ratio. This work is devoted to study the flexural behavior of normal and high strength concrete continuous beams reinforced with glass fiber reinforced polymers (GFRP) bars. Ten continuous beams, with dimensions 150 mm wide × 250 mm deep × 2300 mm long consisting of two equal spans were investigated in this study. The beams were divided into three groups according to the compressive strength of concrete (30, 50 and 70) MPa. Each group consists of three beams with different longitudinal reinforcement ratio (ρfmin, ρfb and 1.5ρfb; where ρfmin and ρfb are the reinforcement ratio at a minimum and balanced condition, respectively). The ultimate load, mid-span deflection, cracks size, concrete strains, GFRP reinforcement strains of the tested beams were verified and contrasted. The experimental results indicate that the increase in the longitudinal reinforcement ratio increases the ultimate load by 125% and decreases the crack size and mid-span deflection by 78% and 57%, respectively. The experimental data were compared with the proposed ACI 440.1R-15 and CSA S806-12 equations. the ultimate load were greater than the calculated results according to (ACI 440.1R-15) by (20%) for beams with (ρmin), while beams with (ρb and 1.5ρb) the ultimate load were less than the calculated results by (9%), cracks size were close to the results according to (ACI 440.1R-15) for normal strength beams, while for high strength beams results were less than the results according to (ACI 440.1R-15), while ISIS-Canada 07 showed good agreement for all tested beams.