Acoustic Emission Evaluation of Structural lntegrity in Repaired Reinforced Concrete Beams
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Fracture tests were carried out on large repaired reinforced concrete beams under cyclic bending load. The fracture process was monitored by acoustic emission (AE), visual observation, and displacement measurement. It was found that distinctive AE signals were produced by the initiation of early tensile microcracks, local slips, main tensile cracks, and large-scale slips between the original concrete and the repaired part. All these different AE sources and their amplitude levels could be clearly discriminated by comparing the AE data with the results of visual observation and displacement measurement. The time and location of crack initiation could be easily determined by monitoring AE, which leads to the conclusion that AE can be a very useful and powerful tool to evaluate structural integrity of repaired reinforced concrete beams. It was revealed that the Kaiser effect starts to break down and high AE activity is observed during not only loadings but also unloadings once large-scale slips have initiated between the original concrete and the repaired part. A concrete beam integrity (CBI) ratio, the ratio of the load at onset of AE and the maximum prior load, is proposed as an effective criterion to measure the severity of damage induced in repaired concrete beams. (Joint research with Tokyo Institute of Technology) |
Copyright 2003, Nippon Physical Acoustics, LTD., All rights reserved
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