Multi-technical analysis of damage process in GFRP-bar reinforced concrete beam

Glass fibre-reinforced polymer (GFRP)-reinforced concrete can be defined as a next-generation structural materiali in which the reinforcing secondary phase consists in corrosion-resistant GFRP bars. This study investigatesvthe damage process of GFRP-bar reinforced concrete beams through the acoustic emission (AE) and digital imagevcorrelation (DIC) techniques. Precursors to identify impending failure in GFRP-bar reinforced concrete beam arevinvestigated by analysing the AE time series. This study verifies the efficiency of the so-called Method of Critical Fluctuations based (MCF-B) approach, alongside the Debski-Pradhan-Hansen (DPH) index, AE Entropy and Natural Time Analysis, as a failure precursor. The results show that: AE features can indicate the stick-slip behaviour between the GFRP bars and the concrete matrix, as evidenced by the tensile-to-shear crack transition obtained by the Rise Angle to Average Frequency (RA-AF) analysis; The MCF-B method effectively identifies the critical region, and its results align with the observations from Natural Time Analysis and AE Entropy Analysis; While b-value exhibits divergent trends beyond this critical region, MCF-B maintains its critical signature, demonstrating the method’s robustness; Low entropy indicates a more ordered state in the system, suggesting that the structure is prepared for impending failure; In the experimental tests, the evolution of the DPH index is also calculated, and this parameter can be used to collect complementary information about the AE test.