Glass fiber-reinforced polymer bar is one of the alternatives presented to overcome the defects related to the steel bars in specific reinforced concrete structural members. One of the most common problems in reinforced concrete structures is the corrosion of steel bars which reduces the lifetime of reinforced concrete structures. Consequently, using GFRP bars can delay the deterioration of a structure and improve its durability.
GFRP bars have a high tensile strength to weight ratio [1,2,3,4,5], high performance against fatigue properties, non-conductivity, and electromagnetic resistance. In addition—as a major advantage—their thermal expansion coefficient is close to that of concrete [6,7,8].
GFRP bars present design challenges which are different than those in the design of traditional reinforced concrete. One major challenge is related to the brittle failure mode of GFRP-reinforced members .
Issa et al.  reported that the GFRP reinforcing bars have a relatively low modulus of elasticity, low ductility, and low stiffness when compared to traditional steel. This reduced stiffness, combined with other factors like a different bond behavior and lower tension stiffening, results in deflections that are larger than traditional steel-reinforced members at any stage of load. Because of these large deflections, structural designs may be governed by deflection limitations .
Many researchers now consider fiber-reinforced polymer (FRP) bars as an efficient and economical method to overcome the corrosion problems inherent to steel rebars in harsh environments. But, definitely, the absence of guidelines performance of GFRP bar-reinforced members is one of the major disadvantages to use GFRP bars as a replacement of steel bars. So, this research was investigated that the performance of concrete beam-reinforced partially/fully glass fiber polymer bars with/without traditional steel bars reinforcement.
Chin et al. reported that the performance of concrete beams reinforced with over-reinforced GFRP bars is safe for design in terms of deformability, and the behavior of beams reinforced by GFRP bars is bilinearly elastic until failure. In addition, its stiffness was found to be reduced after crack initiation when compared to the concrete beams reinforced with traditional steel bars.
D. T. C. Johnson  evaluated the GFRP reinforcement for its suitability as reinforcement for concrete structures and based on the research results, the GFRP stirrups reached stresses that exceeded the minimum design limits. The increased stirrup strength led to overall beam strengths that exceeded the estimated values based on code design provisions.
The investigation of the flexural behavior of high-strength concrete and ultra-strength concrete for beams reinforced with GFRP bars showed that bending stiffness decreases once cracking occurred . A little influence was observed on increasing the post-cracking bending stiffness for the same amount of longitudinal GFRP reinforcement, and a negligible effect was also reported on increasing cracking load.
Seongeun Kim and Seunghun Kim  concluded that the use of FRP bars and traditional steel bars as a flexural reinforcement leads to an increase in the failure load capacity of beams.
Yang et al.  investigated the behavior of concrete beams reinforced by a combination of different types of bars and determining solutions to many shortcomings of FRP-reinforced beams. They conducted a total of 10 experiments and analyzed the behavior related to post-cracking rigidity, crack patterns, ductility, and deflection. It was concluded that using combined reinforcement could control large deflections, deep cracks, and reduce the cracks’ width.
Moon et al.  used a finite element analysis program to investigate the effects of the design variables of concrete beams reinforced with FRP bars. The flexural behavior of the beams was analyzed and the convenience of the analysis model was verified by comparing its results to previous experimental results. Reinforcement ratio, modulus of elasticity of FRP bars, and the compressive strength of concrete were the manipulated variables to investigate their effects on the flexural rigidity of the members and the deflection. Experimental results were compared to the provisions of the ACI 440. The study results indicated that the behavior was mostly affected by the reinforcement ratio, in addition to the increase in the compressive strength of concrete.
Karayannis et al.  studied behaviors of seven concrete beams reinforced with carbon FRP bars, and the experimental results show that the use of CFRP bars can be changed the modes of failure from pure flexural to failure in shear at high ratios of CFRP reinforcement. Brittle failure, decreasing in the number of cracks with larger cracks’ width, and low initial cracks of beam specimen CFRP reinforcement were reported. And from it, the comparison between CFRP beams and GFRP beams of the flexural stiffness of CFRP-beam is higher than of the flexural stiffness of GFRP beam reinforcement.
Hemn et al.  investigated that the flexural capacity and behavior of geopolymer concrete beam reinforced by GFRP bars, and they concluded that the decrease in GFRP reinforcement ratio leads to an increase in ultimate load capacity and decreasing deflection.