Study on the meso-damage characteristics of RC beam under shear failure based on acoustic emission and numerical analysis

Material meso-scopic damage is the fundamental cause of the degradation of the macroscopic mechanical properties of structures, so it is vital to appraise the meso-damage process of various material components. Acoustic emission (AE) technology as a nondestructive testing method can cover the shortage of traditional test to detect the meso-damage. Therefore, in this study, four- point shear tests were conducted on reinforced concrete (RC) beams and AE signals were collected during tests. Results indicated that the shear failure process of RC beam could be divided into three stages based on the correlation between the cumulative AE energy and load- time. Meanwhile, the finite element model (FEM) was established to intuitively obtain the meso-damage evolution process of RC beam in different failure stages. It was observed that the mortar damage, the ITZ damage, the aggregate damage and the reinforcement plasticity damage occurred inside the RC beam and the meso-damage all showed stage characteristics. Besides, the correlation between AE signals and different meso-damage were established by combining the wavelet packet and the cluster analysis. Based on these analysis, the method of assessing the damage severity of RC beam under shear failure was proposed eventually.