Study the effect of the loss in main steel reinforcement of simply supported beams which compensated by precast concrete

This study is intended to experimentally investigate of the structural behaviour of simply supported reinforced concrete beams loss in main steel reinforcement which compensated by precast concrete. six simply supported reinforced concrete beams with various ratios of main steel reinforcement (ρ) equal to 0.00969, 0.00646, and 0.00323. Each two beam have same ratio of reinforcement, one of them supported by precast concrete layer. The layers made by high mechanical propertiesn So, Slurry-infiltrated fibre concrete with 17.7 MPa tensile concrete and 87 MPa compressive strength was used to cast 3 mm thickness layers with 7.5% volume frication. The hard reinforced concrete beam and precast concrete layer were bonded together on beam's tension face to product composite segment. The result show that decrease in ratio of main reinforcement lead to reduction in ultimate load by about 28% and 58% for 0.00646, and 0.00323 as compare with reference beam with ρ = 0.00969. The ultimate flexural capacity of beams with bonded precast concrete segment was found to be best related to the beams without it, where they reach to 98% and 69% of reference beam flexural capacity. On the other hand, the ultimate load increased as compared with same beam without precast layers by about 31.16%, 36.0%, and 62.71% for main steel reinforcement ratios (ρ) equal to 0.00969, 0.00646, and 0.00323 respectively. Furthermore, the strength by precast layers could improve the cracking behaviour, and stiffness of the beams.