DISCRIMINATION OF ACOUSTIC EMISSION HITS FROM DYNAMIC TESTS OF A REINFORCED CONCRETE SLAB

摘要

In the evaluation with acoustic emission (AE) of the damage and state of a concrete structure under a dynamic force, the most relevant information come from the AE hits produced by cracking processes. But, unfortunately, there are other sources of AE, which are unrelated with the damage state of the specimen, as the closing of cracks, friction between different elements, or noise from the testing equipment. The discrimination between AE hits from cracking processes and the other sources is useful in order to have an accurate evaluation. In this paper the classification of AE hits with several signal-processing techniques is investigated. Several dynamic tests were carried out with a reinforced concrete slab attached to a 3-m square MTS shaking table, and during these experiments the AE hits were recorded. The specimen represents, at the 1/3 scale, a flat slab supported on four box-type steel columns, and it was submitted to a simulation of the Campano-Lucano earthquake recorded at Calitri (Italy). After the test, the AE transients were extracted and classified according to several signal parameters. The autocorrelation, wavelet power, kurtosis, RMS in different parts of the signal and approximate entropy were calculated for each signal. A comparison and evaluation of the different classifications according to each parameter is presented.