FOS-Based Prestress Force Monitoring and Temperature Effect Estimation in Unbonded Tendons of PSC Girders

In this study, the effect of temperature variation on prestress force monitoring by fiber Bragg grating (FBG) sensors embedded in prestressing tendons of prestressed concrete (PSC) girders is estimated. First, a fiber optic sensor (FOS)-based prestress force monitoring method is proposed for PSC girders with unbonded tendons. A temperature-effect estimation method is modeled to theoretically estimate the change of prestress force due to the temperature variation. Second, lab-scale experiments are performed on a PSC girder with a FBG sensor-embedded smart tendon. A series of temperature-variation and prestress-loss events are simulated for the PSC girder. Third, the feasibility of the FOS-based monitoring method is experimentally evaluated for the prestress-loss cases under constant temperature. Finally, the effect of temperature variation on the FBG sensor-embedded tendon is evaluated by the temperature-effect estimation method.