Performance of Repaired Macro-Synthetic Structural Fibers and Glass-FRP-Reinforced Concrete Columns

Most of the previous studies mainly concentrated on the axial behavior of glass fiber-reinforced polymer (glass-FRP)-reinforced concrete columns, and no study has been performed on retrofitted glass-FRP-reinforced columns. The present study aims to explore the structural efficiency of retrofitted macro-synthetic structural fiber-reinforced concrete (MSFRC) columns after partial damage. The samples were reinforced with either steel or glass-FRP rebars and strengthened with carbon fiber-reinforced polymer (carbon-FRP) wraps. Twelve samples were fabricated in total. Six samples were longitudinally reinforced with glass-FRP rebars and transversely reinforced with glass-FRP spirals (GMSFRC columns) and the remaining six were longitudinally reinforced with steel rebars and transversely reinforced with steel spirals (SMSFRC columns). The samples were tested up to the 50% reduction in the axial capacity in the post-peak stage and retrofitted utilizing carbon-FRP wraps. The effect of eccentric loads, concentric loads, carbon-FRP wraps, spiral pitch, steel rebars, and glass-FRP rebars on the axial deflection, axial loading capacity, strength index, ductility index, stiffness index, load–deflection efficiency, and failure patterns of samples was assessed before and after retrofitting. The test results showed that the retrofitting of damaged GMSFRC compressive members utilizing carbon-FRP wraps considerably recovered the efficiency of the samples.