Flexure-critical stress and damage identification in RC beam structure using embedded piezoelectric transducers: 2D modelling and experimental investigations

Abstract

This paper proposed a real-time identification approach of flexure-critical stress and damage in reinforced concrete (RC) beam structure using embedded Piezoelectric lead Zirconate Titanate (PZT) transducers. Effect of structural stress and damage were theoretically incorporated into mechanical impedance to derive a novel two-dimensional (2D) embedded PZT-structure interaction model. Analytical analysis was conducted to calculably interpret the identification of tensile/compressive stress and damage based on the electromechanical admittance (inverse of impedance, EMA) signatures. The proposed approach was validated by experiment on an RC beam subjected to four-point bending test, which was continuously monitored by cement-embedded PZT (CEP) transducers. Analytical and experimental results showed that resonance peak and frequency shift of the EMA spectrums of CEPs exhibited converse behaviors when responding to tension and compression stresses, while typical frequency decrease and peak increase accurately indicated the occurrence of initial cracking. Comparative studies also revealed that CEPs were superior to visual inspection and bonded PZT transducer in identification of concrete cracking, and that located in compressive zone was more efficacious in prediction of the forthcoming yield and final failure of the RC beam. Results of this study cogently demonstrated the potentialities of CEP transducer as a means of on-line monitoring of stress/damage in flexure-critical RC infrastructures.