Measurement of internal strain of FRP concrete structure by fiber optic sensor

Study on the mechanical behavior of FRP-concrete structure is mainly by means of theoretic calculation and experimental analysis. Comparing with the electrical strain gauge which are generally used to measure the external strain for short term, fiber optic sensor which is embedded in the interface of FRP tube and inner concrete, can easily not only measure the internal strain of the structure, but also monitor the crack expanding of inner concrete. The Mach-Zehnder interferometer is applied in the strain measurement. The optical parameter of fiber optic sensor is identified in the calibration experiment, so the internal strain can be calculated by processing the experimental optical signal. The method of automatic data collection and signal processing of the measuring system is presented in the paper.