Fracture characteristics analysis of FRP-reinforced concrete based on acoustic emission

Abstract

To study the acoustic emission (AE) characteristics of fibre-reinforced polymer (FRP)-reinforced concrete during the fracture process, three-point bending tests of FRP-reinforced concrete beams with cracks were carried out. The AE characteristics of FRP-reinforced concrete beams with different bonding lengths and different bonding layers were analysed based on the AE parameters, and the effect of the fracture parameters was studied. The test results reveal that the crack initiation load and peak load of single-layer FRP-reinforced concrete beams first increase and then decrease with the increase of bonding length. The failure mode of multi-layer FRP-reinforced concrete beams is a kind of dangerous brittle failure, which easily forms the ‘super-reinforcement failure’ mode. The ductility of single-layer FRP-reinforced concrete beams with a bonding length of 25 cm is optimal, which can effectively delay crack propagation. By combining the load–time curves, AE ringing count–time curves and AE energy–time curves, the time points of crack initiation load and instability load can be accurately determined. The analysis of RA–AF (ratio of ringing count to duration–ratio of rise time to maximum amplitude) and clearance factor index can be used to evaluate the damage state of FRP-reinforced concrete beams.