Monitoring bond-slip behavior of CFRP-RCESC beams using piezoelectric active sensing method

Combination of carbon fiber reinforced polymer (CFRP) tendon and reinforced concrete encased steel composite (RCESC) beam can improve the workability and the energy dissipation capacity of members. In this paper, three RCESC beams reinforced with steel bars or CFRP bars were designed and fabricated to study the bond-slip behavior between I-shaped steel and CFRP reinforced concrete and the damage states between bond-slip interfaces of the beams. The lead zirconate titanate (PZT) patch as stress wave actuator, the smart aggregates (SAs) were installed in concrete as the sensors to collect the stress wave signal. A method based on piezoelectric active sensing was developed to monitor the bond-slip damage of CFRP-RCESC beam. The changes of responding signals were characterized in time- and frequency- domains. The characteristic information of bond-slip damage was further quantified by wavelet packet energy. Results show the bond-slip resistance of the CFRP-RCESC beams can be improved by increasing reinforcement ratio and elastic modulus of the main bars. The bond-slip damage process of the specimens can be effectively monitored by the active sensing method.