Experimental Study on the Damage Mechanism of Reinforced Concrete Beams Based on Acoustic Emission Technique

The purpose of this paper is to investigate the developmental process of internal damage in prestressed concrete beams under static loading conditions. We conducted static loading tests on two prestressed reinforced concrete beams and one ordinary reinforced concrete beam. Acoustic emission (AE) technology was employed to dynamically monitor the entire process of the test beams simultaneously. The energy and ring count AE characteristic parameters were studied, and the frequency domain characteristics of acoustic emission signals from three test beams were analyzed. The actual failure process of the test beams was compared with the AE characteristic parameters and the waveform frequency distribution. Furthermore, the corresponding relationships between the actual failure process and the AE characteristic parameters were analyzed. Additionally, the frequency distribution of waveforms was examined. The obtained data, including deflection, strain, and prestress variation within the beams, were combined with theoretical calculations to explore the damage development law of simply supported reinforced concrete beams during the entire failure process. Comparative studies revealed a strong correlation between the actual failure processes of the three test beams and the AE characteristic parameters as well as the waveform frequency distribution. The strain variation trend of the ordinary reinforced concrete beam closely matched the AE signal characteristics, with the critical load often occurring at around 40% of the ultimate load. The strain and deflection variations of the prestressed reinforced concrete beams exhibited a robust correspondence with the AE signal characteristics. The critical load typically manifested at approximately 80% of the ultimate load. The ultimate load of the prestressed reinforced concrete beams decreased by approximately 20% under cyclic loading conditions compared to hierarchical loading.