High-durable smart steel tie rod based on FBG absolute measuring technology

In view of the lack of effective methods for the measurement of internal force under the construction loads and the long-term monitoring in service of steel tie rods, a novel high-durable smart steel tie rod based on the fiber Bragg grating (FBG) absolute measuring technology and packaged by glass fiber reinforced plastic (GFRP) was developed. The strain detected by the FBG strain sensors has a very good linearity and repeatability under 85% tensile load of the theoretical yield load, and the measured rod force agrees well with the stretching force (relative error ≤4%). The advantages of the smart steel tie rod, such as durability, anti-corrosion, electro-magnetic resistance, low cost and absolute measurement, were verified. It can indicate the state of stress in any phase, and can be regarded as a large strain load sensor used to measure the stress of the steel tie rod or some components adjacent to it. It is suitable for monitoring the stress exerted on the steel tie rod sturctures serviced in harsh environment.