Acoustic emission-based damage analysis of steel fibre reinforced concrete in progressive cyclic uniaxial tension tests

Although direct tension tests (DTT) on steel fibre reinforced concrete (SFRC) are difficult to perform, they are of interest because of the uniform tensile stress distribution. Therefore, this paper reports on 31 DTT under monotonic or progressive cyclic loading. All test specimens are notched and continuously monitored with acoustic emission (AE) sensors and clip gauges. The aim is a better understanding of the (cyclic) uniaxial tensile behaviour of SFRC by AE-based damage monitoring. The research shows the importance of fibre distribution and orientation on the load–displacement behaviour. Micro-cracking is detected in the loading cycle prior to fracture by means of AE analysis. Failure mode analysis of the AE signals shows more than 99% mode I damage and indicates the onset of macro-cracking. Localisation of AE events validates the fibre position, the damage stages and the main crack position. Based on AE analyses, differences in damage development are identified even when the post-peak behaviour of the DTT specimens is similar. As such, the obtained experimental data set has an added value to the limited existing research of AE monitoring during DTT on SFRC.