Acoustic emission monitoring of CFRP cables for cable-stayed bridges

The advantages of fiber-reinforced polymer (FRP) composites include excellent corrosion resistance, high specific strength and stiffness, as well as outstanding fatigue behavior. The University of California San Diego's I-5/Gilman Advanced Technology Bridge Project will help demonstrating the use of such materials in civil infrastructures. This paper presents an acoustic emission (AE) study performed during laboratory proof tests of carbon fiber-reinforced polymer (CFRP) stay-cables of possible use in the I-5/Gilman bridge. Three types of cables, both braided and single strand, were tested to failure at lengths ranging from 5500 mm to 5870 mm. AE allowed to monitor damage initiation and progression in the test pieces more accurately than the conventional load versus displacement curve. All of the cables exhibited acoustic activities revealing some degree of damage well before reaching final collapse, which is expected in FRP's. It was also shown that such cables are excellent acoustic waveguides exhibiting very low acoustic attenuation, which makes them an ideal application for an AE-based health monitoring approach.