A Study on Axial Load-Bearing Capacity and Compression Creep Behavior of Concrete Reinforced with Steel and GFRP Bars

This study investigates the axial load capacity, failure behavior, and compression creep performance of concrete columns reinforced with steel and glass fiber reinforced polymer (GFRP) bars. The experimental program utilized circular columns measuring 200 mm in diameter and 800 mm in height with difference reinforcements. Longitudinal reinforcement ratios (1.50%, 2.88%, and 5.12%) were prepared for both steel and GFRP bars, combined with transverse reinforcement, ties and spirals, at spacings of 150 mm and 75 mm. Results demonstrated that increasing the GFRP bar reinforcement ratio significantly enhanced axial load capacity. Furthermore, reduced tie spacing and the use of spiral reinforcement could improve both load capacity and axial deformation. However, at identical reinforcement ratios, GFRP bar reinforced concrete exhibited lower axial capacity than that of concrete reinforced with teel. For compression creep, it was revealed that the greater long-term deformation in GFRP bar reinforced specimens was found attributed to the lower elastic modulus of GFRP under sustained loads.