Rail elevated bridge bearing displacement monitoring based on FBG sensor

In order to know the bridge bearing operation condition, monitoring bearing displacement was an alternative way. Considering the special field environment of rail elevated bridge and some existing problems of EM-based sensors, needle-shape differential FBG displacement sensors were designed which ensured the long-term stability monitoring under EMI environment. Comparing to the wire-shape FBG displacement sensor, the contact measure type through the sensor needle-shape rod in this paper not only simplified the installation process in-situ, but also could reflect the accurate test direction of bridge bearing. The good linear relationship between sensor wavelength and load verified the rationality of designed differential structure. The practicability in actual engineering application of needle-shape FBG sensor was revealed by a certain rail elevated bridge bearing displacement continuous monitoring results.