Experimental study on the mechanical properties of corroded RC columns repaired with large rupture strain FRP

This paper presents experimental results of the mechanical properties of corroded reinforced concrete (RC) columns repaired with large rupture strain (LRS) fiber-reinforced polymer (FRP). This work seeks to evaluate the effects of corrosion-induced damage, including concrete cracks and rebar buckling, on the confinement effectiveness of LRS-FRP. A total of sixteen RC columns were corroded to different extents by an electrochemical method and then repaired by wrapping them with FRP. A series of monotonic axial compression tests were conducted on these repaired specimens that were characterized by their corrosion conditions and FRP confinement rigidities. The test results show that LRS-FRP confinement effectively enhanced the mechanical properties of corroded RC columns. However, the existence of corrosion weakened the rebar cross-sections and further damaged the confined inner concrete, significantly influencing the compressive strength and ductility of the repaired RC columns. In addition, rebar buckling was more pronounced at higher corrosion rates, which affected the hoop strain distribution of the FRP and further reduced its confinement effectiveness. The existing ultimate condition models for confined concrete are also validated by the current test results, indicating that satisfied predictions can be made as the corrosion effects on confinement effectiveness are properly considered in these models.