Deflection and Cracking of Fiber-Reinforced Self-Consolidated Concrete Beams Reinforced with GFRP Bars under Cyclic Loading

Deflection and crack width under service loads are crucial factors that dictate the flexural design of elements reinforced with glass fiber–reinforced polymer (GFRP) bars, primarily due to their relatively low elastic modulus. This study investigated the impact of incorporating fibers on the serviceability performance of self-consolidating concrete (SCC) beams reinforced with GFRP bars. Eight full-scale concrete beams—each measuring 3,100 mm in length, 200 mm in width, and 300 mm in height—were fabricated and tested until failure under four-point bending cyclic loading. Six specimens were cast using fibers, while the other two were cast with normal SCC as reference specimens. The test parameters included polypropylene (PP) fiber volume (0%, 0.5%, and 0.75%), fiber combination (macro PP fibers and a mix of macro PP and micro basalt fibers), and longitudinal reinforcement ratio (0.78% and 1.66%). The test results revealed that increasing PP fiber volume and reinforcement ratio improved the serviceability and flexural performance of the beams under cyclic loading by effectively restraining crack width and reducing deflections at both service and ultimate limit states. Furthermore, combining micro basalt fibers with macro PP fibers notably enhanced the serviceability parameters of beams with both low and high GFRP reinforcement ratios, surpassing beams reinforced solely with macro PP fibers. A theoretical prediction per North American codes and design guidelines was conducted, including deflection and crack width, and these results were subsequently compared to the experimental findings.