Acoustic Emission Monitoring of an Aging Dock

Acoustic Emission Monitoring of an Aging Dock


Photograph of the aging dock	Sensor placement on the concrete surface

Schematic illustration of the loading test

Structural integrity of RC beams was evaluated in an aging dock. A repaired beam and a damaged one without repair were subjected to three loadings by running a dump truck with three different load levels i.e. empty (113kN), half load (142kN), and full load (171kN). The above figure and photographs show how the tests were performed. Two PAC R15 and R6 sensors were attached on the beams. However, only the data collected by R6 sensors could be analyzed since there were no significant AE signals detected by R15 sensors due to high attenuation at higher frequencies. A strain gage was attached on the main reinforcing bar to measure strain changes during the loadings. Two cracks the maximum opening width of which reached 0.8 mm were visually observed on the surface of the unrepaired beam and measurements of corrosion potential confirmed that serious damages due to corrosion of the reinforcement existed. Strain gage measurements showed that the strain change is much larger in the unrepaired beam than the repaired one for the same loadings. Although the repaired beam (no damage) was very quiet, high AE activity was observed since the first loading in the unrepaired one. The Kaiser effect breaks down during the third loading and high AE activities were seen during the second and third unloadings. The AE source during the third unloading was thought to be frictions due to slips between the reinforcement and the concrete.