Application of acoustic emission analysis-pullout experiments with bonded anchors

In recent years, fastening technology has steadily become more important in construction practice, where bonded anchors as connecting elements are at the forefront. The production of durable and secure connections necessitates an in-depth knowledge of the mode of action of bonded anchors, their interaction with the bonding substrate, and the resulting load-bearing capacity. In construction practice, pullout experiments are performed on anchors to assess their load-bearing performance. However, the processes involved in crack formation before anchor failure cannot be determined in classical pullout experiments. Acoustic emission analysis was combined with pullout experiments to study the onset and evolution of damage until anchor failure. Acoustic emission analysis has emerged as an extremely useful method for observing the dynamic process of crack formation, crack evolution, and, ultimately, the failure of bonded anchors in concrete during pullout testing. This process results in acoustic emissions that can be recorded by a suitable measuring technique and sensor technology. The determination of the coordinates of the sources of sound emission (localization) is a particularly important aspect of the analysis of acoustic emission data. The presented results show good agreement between crack patterns observed on the surface of concrete specimens and the distribution of the acoustic emission sources inside the specimens. It was possible to show that the sources of acoustic emission shift to greater concrete depths with increasing load on the bonded anchors. The sources of acoustic emission were therefore in good agreement with stress distributions determined by numerical simulations.