Experimental evaluation of flexural behavior of High-Performance Fiber Reinforced Concrete Beams using GFRP and High Strength Steel Bars

Substitution of only steel rebar with fiber-reinforced polymer (FRP) or in combination with steel rebar has been recommended to reduce corrosion effects in steel rebar. This paper has pursued the impact of hybrid concrete beams reinforced with High Strength Steel Bars (HSS) and Glass Fiber-Reinforced Polymer Bars (GFRP) manu-factured employing High-Performance Fiber-Reinforced Cementitious Composites (HPFRCC) instead of con-ventional concrete through experimental tests. Seven concrete beams including conventional concrete and HPFRCC in three separate groups, having identical compressive strengths and longitudinal steel reinforcement ratios, have been tested following respected codes and regulations to supply sufficient development lengths using GFRP headed bars, under four-point loading tests. The first and second groups, each represented one conven-tional concrete beam and an HPFRCC model with GRFP or HSS; the third group included three HPFRCC beams using GRFP and Steel rebar to assess flexural behavior of beams under different reinforcement ratios. Experi-mental results indicated that HPFRCC beams demonstrated improvements in their load capacity, flexural strength, bending stiffness, ductility, and energy absorption compared to similar conventional concrete beams. Also, in hybrid beams compared to steel reinforced concrete beams both cast with HPFRCC, the more the effective reinforcement ratio of both single and hybrid bars increased, the more ductility was improved between 37 and 88 percent. Displacement ductility of hybrid beams having effective reinforcement ratios up to 1.35 and 1.25 times more than the balance ratio was increased 23 and 37.5 percent, respectively. Energy absorption for HPFRCC beams reinforced only with GFRP or steel rebar was increased 31 and 250 percent compared to identical conventional concrete beams, respectively. In hybrid compared to GFRP reinforced beams both cast with HPFRCC, the more effective reinforcement ratio increased, the more energy absorption was increased in a range of 51 up to 174 percent. Therefore, it can be concluded that using the hybrid of GFRP and HSS bars result in up to 30 percent improvement in flexural strength because of the effective performance of GFRP after steel rebar yielding and ductility increase due to HSSs yielding.