Experimental Investigation on the Behavior of Hollow-Core Glass Fiber-Reinforced Concrete Columns with GFRP Bars

Steel reinforcing bars, helices, and fibers in concrete columns are susceptible to corrosion, particularly in aggressive environments. This study experimentally investigated the use of corrosion-free glass fiber-reinforced polymer (GFRP) bars and GFRP helices in hollow-core circular glass fiber concrete (GFC) columns. The influence of the addition of the glass fibers, loading conditions, and pitch of the helices was investigated. The experimental program consisted of 12 circular specimens with an outer diameter of 214 mm and an inner circular hole diameter of 56 mm. Nine specimens (850 mm high) were tested under concentric and eccentric axial loading and three specimens (1,500 mm long) were tested under four-point bending. The experimental results showed that, for a similar amount of reinforcement, the GFRP bar-reinforced hollow-core glass fiber concrete (GFRP-HC-GFC) specimens achieved 12%-18% lower maximum axial load than the GFRP bar-reinforced hollow-core nonfibrous concrete (GFRP-HC-NFC) specimens under concentric and eccentric axial loadings, as evident in the P-M interaction diagrams of GFRP-HC-NFC and GFRP-HC-GFC. However, GFRP-HC-GFC specimens achieved 5%-20% higher ductility than the GFRP-HC-NFC specimens under different loading conditions. The experimental results also showed that the GFRP-HC-GFC specimens experienced a lower number of cracks and smaller crack widths than the GFRP-HC-NFC specimens under eccentric axial loading and four-point bending. In addition, the GFRP-HC-GFC specimens with 30-mm pitch of the GFRP helices achieved 2%-34% higher maximum load and 7%-55% higher ductility than the GFRP-HC-GFC specimens with 60-mm pitch of the GFRP helices under different loading conditions.