Effects of CFRP/GFRP flexural retrofitting on reducing seismic damage of reinforced concrete frames: a comparative study

Flexural retrofitting of structures using glass/carbon fibre reinforced polymer (GFRP/CFRP) has been widely investigated. However, comparison on the effects of GFRP/CFRP flexural retrofitting at plastic hinges on reducing the potential seismic damage of reinforced concrete (RC) structures is hardly found in the literature and is thus aimed by this study. Toward this aim, two-, four- and eight-storey RC frames were chosen to represent different building structures. These frames were then retrofitted by CFRP/GFRP bonded sheets to increase flexural capacities of beams and columns at plastic hinge regions. The original, CFRP and GFRP retrofitted frames were modelled using nonlinear hysteresis elements. After verification, nonlinear time-history analyses of those frames under various seismic intensities were carried out, followed by cumulative damage analyses. Damage states of original, CFRP and GFRP retrofitted frames were compared with one another. The obtained comparison results reaffirmed the effectiveness of CFRP and GFRP flexural retrofitting. More importantly, obtained results indicated that CFRP is more effective than GFRP on reducing seismic damage of RC structures when they are employed for flexural retrofitting. These outcomes can help in deciding on the FRP type to be used for flexural retrofitting of RC structures. © 2019, Springer Nature Switzerland AG.