Stability and reliability of fiber optic measurement systems: basic conditions for successful long term structural health monitoring

Abstract

Recent developments in fiber optic sensors for monitoring civil structures have been of great help for engineers dealing with these structures. After literature survey it is observed that while using fiber optic sensor system for health monitoring of civil structures not much attention is given to the core quality of the fiber, types of coating on fiber, implementing methodologies, handling of fiber optic sensors and their long term effect on reliability of the performance of the monitoring system. These issues are important because the structural conditions, stress level and environment in which fiber optic sensors are placed are different from telecommunication industry. In this paper issues related to long term structural health monitoring of civil structures are investigated. The issue of the fatigue property of optic fiber is discussed since reversal bending of the fiber may cause adverse effect on the light carrying capacity of the fiber. Other long term structural health monitoring (SHM) issues such as life of fiber, strain transfer process from fiber core to coating, calibration of fiber and selection of fiber are also discussed based on the experiments carried out for successful implementation of long term health monitoring of civil structures. The main objective of these experiments is to come up with comprehensive long term structural health monitoring system for strain measurement.