A Low-Cost Prestress Monitoring Method for Post-Tensioned RC Beam Using Piezoelectric-Based Smart Strand

Thanh-Cao Le,Duc-Duy Ho,Thanh-Canh Huynh,Thi Tuong Vy Phan,Trung-Hau Nguyen

doi:10.3390/buildings11100431

Abstract

This study proposes a cost-effective prestress monitoring method for post-tensioned reinforced concrete (RC) beams using a smart strand. Firstly, the concept of a piezoelectric-based smart strand and its implementation for prestress force monitoring are developed. The smart strand is prepared by embedding inexpensive and high-sensitivity electromechanical impedance (EMI) sensors in a steel strand. Next, the feasibility of the proposed method is experimentally verified for prestress force monitoring of a simple supported post-tensioned RC beam. A smart strand prototype is fabricated and embedded into a 6.4 m RC beam which is then prestressed with different levels. For each prestress level, the EMI responses of the smart tendon are measured and the EMI features are extracted for prestress force monitoring. The results showed that the EMI signals of the smart strand showed strong resonant peaks that varied sensitively to the prestress level of the beam. The prestress change in the prestressed RC beam was successfully estimated by using linear regression models of the EMI features.

Highlights

Structural health monitoring (SHM) of prestressed reinforced concrete (RC) structures has increasingly received significant interest from civil engineers, maintenance crews, and researchers
Inspired by the concept of the fiber Bragg grating (FBG)-based smart tendon and the advantages of the low-cost electromechanical impedance (EMI)-based technique, we develop a cost-effective prestress monitoring method for post-tensioned RC beams using the piezoelectric-based smart strand
To prepare the smart strand, a shows a high sensitivity to the PS changes with clear shifts of resonant impedance peaks

Summary

Introduction

Structural health monitoring (SHM) of prestressed reinforced concrete (RC) structures has increasingly received significant interest from civil engineers, maintenance crews, and researchers. One of the first attempts was conducted by Saiidi et al [4] In their research, they analyzed the effect of the PS force on the dynamic properties of RC beams and concluded that periodic monitoring of the dynamic characteristics can be useful to discriminate the PS losses. They analyzed the effect of the PS force on the dynamic properties of RC beams and concluded that periodic monitoring of the dynamic characteristics can be useful to discriminate the PS losses Based on this pioneering study, Kim et al [5] developed a theoretical formula to estimate the PS loss of an unbonded strand in a prestressed beam by using the shift in modal frequencies. PS loss, in most cases, causes only small changes in the vibration frequencies of the prestressed

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Conclusion