Repair Effects and Acoustic Emission Technique–Based Fracture Evaluation for Predamaged Concrete Columns Confined with Fiber-Reinforced Polymers

AbstractDuring the last two decades, the use of fiber-reinforced polymer (FRP) in the retrofitting of concrete structures has been widely studied. However, there is limited research on the effect of initial concrete damage on the retrofitting effect of FRP on concrete columns, especially when the initial damage is severe. For FRP-confined concrete columns, the fracture process inside the concrete is covered by FRP and is not visible to inspectors during the service period. This paper investigates these problems through an experimental study of 28 100×100×300  mm concrete columns using axial compression tests and acoustic emission (AE) fracture monitoring. Prior to FRP wrapping, three different damage levels were assigned to the concrete columns. The stress-strain results showed that the predamage levels had a small effect on the ultimate strength of the FRP-confined predamaged concrete columns, even when the predamage was severe, whereas the axial/lateral strains were more affected by the predamage levels...