Localization of the Structural Damage of Prestressed Reinforced Concrete Beam through Acoustic Emission Technique

Among Non-Destructive Diagnostic Techniques (NDTs), Acoustic Emission (AE) is particularly useful to evaluate and/or monitor the material properties of structures and their degradation over time. For instance, this method permits identify early micro-fractures by depicting the release of mechanical energy of an elastic wave radially propagating through the material from the fracture zone, obtaining the possibility to localize the damage of the investigated specimen. Despite the large number of localization strategies that have been examined in the literature, there are nowadays no specific and standard guidelines. Within this framework, in this paper, the results of an AE experimental test performed on a prestressed reinforced concrete joist subjected to a four-point bending load are presented. The data collected during the test will be analysed focusing in particular on the hits cumulative curves and hits energies for each channel, showing how the overall behaviour of these parameters provides interesting insights into the specimen response. Finally the linear localization of the events produced during the test will be reported and correlated with the theoretical expectations, in terms of tensile and shear cracks. The results will confirm the expectations, reporting the main events in the central region of the specimen, that experiences the maximum constant bending momentum. All the findings of this test will show a setup for the early detection of micro-fractures in prestressed reinforced concrete elements, providing an interesting base for the extension of the technique to buildings and general structures.