Comparison of CFRP and GFRP Wraps on Reducing Seismic Damage of Deficient Reinforced Concrete Structures

The effectiveness of glass/carbon fibre reinforced polymer (GFRP/CFRP) wraps at plastic hinges has been confirmed; however, their respective effectiveness on reducing seismic damage of deficient reinforced concrete structures has hardly been compared. The current study aims at this comparison, providing some useful information to realise the better FRP for confinement retrofitting of reinforced concrete structures poorly confined due to deficient transverse reinforcement. Four- and eight-storey poorly confined reinforced concrete frames were selected to represent low- and mid-rise building structures, respectively. These deficient frames were then strengthened by CFRP/GFRP wraps via external confinement. Inelastic time history and cumulative damage analyses of the original, CFRP- and GFRP-retrofitted frames were performed. The damages of CFRP- and GFRP-retrofitted frames were compared with each other and with the damage of the original frame. The comparison results show that CFRP and GFRP wraps at plastic hinges substantially reduce damage. More importantly, GFRP wraps are more effective than CFRP wraps by reducing a higher amount of the cumulative damage index. The conclusions can help in deciding on the type of FRP to be used for confinement retrofitting of RC structures poorly confined due to deficient transverse reinforcement.