Acoustic emission and damage evolution in steel fiber-reinforced concrete beams under cyclic loading

Abstract

In this work, the Acoustic Emissions (AEs), detected in real-scale Reinforced Concrete (RC) beams which have been tested under four-point bending, are investigated and correlated with their structural responses and damage evolutions. Two different reinforcing bar arrangements, with or without shear stirrups, were designed in order to obtain bending or shear failure modes, respectively. Moreover, some of the beams were casted with the addition of steel fibers in the concrete mixture. A loading procedure characterized by several cycles of increasing amplitude up to failure was implemented. Beams failure behaviors and the aptitude of four AE-based indices to assess their damage level, are presented and compared. Moreover, some relevant variables possibly affecting the indices performance are analyzed. The steel fibers enhanced shear strength by restricting the development of inclined cracks in the beam without stirrups. Finally, it can be figured out that AE indices showed a quite good correlation with cracking initiation and progression. Therefore, they proved to be competent for both monitoring the RC beams loading response and detecting eventual local damages, even for fiber-reinforced concrete members.