Effect of corrosion-damaged RC circular columns enveloped with hybrid and non-hybrid FRP under eccentric loading

Abstract

The paper presents the effect of corrosion-damaged reinforced concrete (RC) columns with circular cross section enveloped (i.e. wrapped) with externally bonded hybrid and non-hybrid fibre-reinforced polymer (FRP) reinforcement. This study consisted of 18 RC circular columns with a diameter and height of 130 mm and 780 mm, respectively. These specimens were divided into three divisions, namely (i) no corrosion, (ii) mild corrosion and (iii) severe corrosion activities. All the mild and severe corroded columns, except control column, were exposed to corrosion activity, repaired with FRP and tested under eccentric loading. However, the columns without any corrosion activity were enveloped with FRP reinforcement and tested under eccentric loading. The corrosion process in RC columns was accelerated by impressing direct current on the steel reinforcement cage, adding 5% of NaCl in concrete mixture and wet/dry cycles. The variables investigated were different period of corrosion levels, plies of FRP (carbon and glass) reinforcement, hybrid (i.e. combination of carbon and glass FRP plies) and non-hybrid FRP (i.e. carbon or glass) reinforcement. From the experimental results, it was found that the external FRP confinement significantly increased the load-carrying capacity of the corrosion-damaged RC circular columns by 8% to 36% for mild corrosion level and 21% to 34% for severe corrosion level over the unconfined corrosion-damaged RC circular columns. Moreover, the results show that the performance of corrosion-damaged RC circular columns enveloped with hybrid FRP was better over the non-hybrid CFRP and GFRP RC circular columns. However, the results of CFRP enveloped circular columns were close to the hybrid FRP strengthened circular columns.