Acoustic emission-based indicators of shear failure of reinforced concrete beams without shear reinforcement

Many existing concrete structures require effective assessment of the bearing capacity. A critical failure mode is shear, especially for concrete structures without or with limited shear reinforcement. The shear failure is brittle and often leads to loss of property and lives. Therefore the shear failure should be indicated before it occurs. A potential solution is to use acoustic emission (AE) monitoring, which is sensitive to minor changes in concrete, even micro-cracking, both on the surface and inside the structure. By combining the knowledge of shear failure processes and AE techniques, this paper presents an AE-based shear failure indication system. The system automatically identifies three levels of structural damage levels up to shear failure, which are categorized from minor to severe levels as green-light, yellow-light, and red-light criteria. The 'traffic light system' is validated using six shear tests on full-scale reinforced concrete beams without shear reinforcement. The robustness of the system is also validated across these tests. • Strut integrity can indicate shear failure of reinforced concrete structures. • Strut integrity is evaluated by the probability density of AE events. • The AE system shows three structural degradation levels for shear, termed 'traffic light system’. • Users can make decisions according to the physical background of the AE-based indicators. • Shear failure models combined with AE data analysis enable the prediction of shear failure.