Bridge Health Monitoring Using Distributed Fiber Optic Sensing

Due to the frequent occurrence of bridge accidents in recent years, bridge safety monitoring has attracted increasing attention. Usually there are dozens of types and thousands of sensors distributed on a bridge, which are used to monitor the strain, inclination, displacement, deflection, acceleration, temperature and humidity of the bridge. Compared with traditional monitoring methods, distributed optical fiber sensing technology can obtain thousands of sensing points on a single optical fiber for simultaneous measurement and accurately locate the fault location.

Model of cable-stayed bridge

We use OFDR distributed optical fiber sensing technology to demonstrate the strain measurement at various positions of a cable-stayed bridge model and combines the our newly developed 3D reconstruction software to visualize the strain results of real-time monitoring of the bridge.

OSI-S High Resolution distributed optical fiber sensing

We arrange tight-sheathed optical fibers as the bracing cable on both sides of the bridge to monitor the strain of bracing cable. Two sections of optical fibers are arranged at the bottom of the bridge to monitor the vehicle load. The monitoring equipment used is OSI – high-precision distributed optical fiber sensing system. Its principle is based on OFDR optical frequency domain reflection technology, the highest spatial resolution is 1mm and the repeatability is ±1με

Real-time reconstruction of the 3D strain field of the bridge

Press the bridge to carry out the loading test. Press different positions, the software will display in real time and locate it accurately. The green part in the software represents zero strain and no loading state, the blue part represents the positive strain and stretch state, and the red part represents the normal strain and stretch state. The figure shows the strain distribution when the tops of the two towers are tilted inward. The inner cable shrinks to a negative strain and the outer cable stretches to a positive strain.

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