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

Existing concrete bridges require efficient assessment due to increasing traffic load and degrading material. For reinforced concrete structures without shear reinforcement, a typical failure mode is shear, which often means a total loss of structural capacity and does not have an obvious warning beforehand. To indicate the shear failure before it occurs, we need to monitor the structural behaviour like the location and magnitude of the cracks. Acoustic emission (AE) is a favourable technique that can detect the internal cracking sensitively. This dissertation develops an AE system to indicate the shear failure before it occurs. AE methods are improved. A deeper understanding of AE from concrete cracking is provided. Based on the new insights of AE, a ‘traffic light system’ is developed where the green-, yellow- and red-light criteria show three damage levels of the structure. The new system has been validated using experiments on different types of structures. In the end, a general guidance is provided on implementing the AE-based indicators in load testing of a concrete structure.