Acoustic Emission Behavior during Damage Development of Reinforced Concrete Beam

As a preliminary study for applying the acoustic emission(AE) technique to assess the integrity of concrete structures, AE behavior of a reinforced concrete beam under cyclic loads of various loading stage was examined by laboratory experiments. By analyzing failure behavior of a reinforced concrete beam in the AE point of view, it was presumed that major sources of AE signals in concrete were micro-crack initiation, development of flexural and diagonal tension crack, and the friction between track surfaces. In addition, cyclic loading tests and failure test were carried out to obtain the AE responses under various loading conditions. The analysis of the signal patterns was aimed at discussing the differences between the normal signal and the abnormal signal, which represent the safe condition and the condition of developing damage, respectively. In this study, especially, the behavior of friction signals from crack surfaces, which were usually treated as noises, was considered as a typical pattern of the normal signal. As a result, significant differences between the normal and abnormal signal patterns were observed in the such parameters as the AE hit rate, magnitude of the primary or secondary AE peak, and AE response according to the sensor location. Based on the preliminary results, this new approach for practical AE application may provide a promising method for estimating the level of damage and distress in concrete structures