Long‐Term Monitoring Reliability and Life Prediction of Fiber Bragg Grating‐Based Self‐Sensing Steel Strands

Abstract

To analyze the long‐term monitoring reliability and life expectancy of FBG‐based steel strands, accelerated corrosion and tensile tests were carried out and a life‐prediction model was constructed. The validation test results indicated that the monitoring strain sensitivity of FBG‐based steel strands decreases with an increase in solution concentration and time in a corrosive acidic environment. When the sensitivity dropped to about 80% of its initial value, the FBG sensor suddenly failed. The life‐prediction model indicates that the predicted monitoring life of an FBG sensor is about 56 years in an unstressed condition but about 27 years under the stressful conditions that FBG‐based steel strands are subjected to in their working environment. So, to improve their monitoring reliability and monitoring life, it is suggested that FBG‐based steel strands might be prepared by “pre‐loading.”