Acoustic emission based damage assessment method for prestressed concrete structures: Modified index of damage

•Acoustic emission (AE) ability for damage assessment was investigated.•Prestressed concrete beams were tested using CLT method.•Cumulative AE energy was used to calculate index of damage.•A modified index of damage was proposed.•The index increases with the increase of load and has the ability to detect specimen yield.

Eight prestressed specimens were subjected to cyclic load testing while being monitored with acoustic emission (AE). Five were pre-cracked and corroded to different levels, prior to testing, to examine the ability of AE to detect damage for different structural conditions. An index of damage introduced in a previous study based on cumulative AE energy was investigated for damage assessment. The index values showed a clear correlation with the observed amount of damage. However, the method is constrained to laboratory applications as it requires the continuation of the test until the specimen surpasses the level of maximum admissible damage. A modified index of damage (MID) is proposed in this study to enable field applicability. The modified index showed promising results and enabled the detection of the yielding point for both cracked and un-cracked specimens. Further work is desirable to validate the acceptance thresholds and extrapolate the results to actual in-service structures.