Damage accumulation on deformed steel bar to concrete interaction detected by acoustic emission technique

Acoustic emission (AE) signals and relative displacements were simultaneously recorded on pull-out specimens subjected to monotonic, cyclic and long-term loads. The bond length was twice the rib spacing. Most of the signals were observed during an increase in load or applying the cyclic load, however, signals were recorded during cycling and under constant load as well. The AE signal patterns were compared by applying the coherence spectrum analysis based on Fourier transforms of the signals. The internal damage accumulation, defined as the cumulative AE amplitudes, showed similar tendencies to the slip development both under cyclic and long-term loads.