The application of Fiber Bragg Grating (FBG) products in bridge engineering represents an important development direction of modern structural health monitoring technology. As an advanced optical sensing technology, FBG, with its unique technical advantages, is playing an increasingly important role in the full life cycle management of Bridges.

In terms of bridge structure monitoring, FBG sensors are mainly applied to several key parts. For the main beam structure, by pre-embedding or surface pasting FBG sensors inside the concrete box girder or steel beam, the strain distribution caused by factors such as vehicle load and temperature changes can be monitored in real time. This kind of monitoring is particularly important for discovering potential stress concentration areas. In cable-supported Bridges, FBG is widely used for the force monitoring of cables or hangers, and it assesses the safety status of the structure by precisely measuring the changes in cable force. For bridge piers and bearings, FBG sensors can monitor uneven settlement and displacement changes, providing an important basis for the stability assessment of Bridges.

The advantages of FBG technology in bridge monitoring are mainly reflected in four aspects. Firstly, it features high measurement accuracy, capable of detecting minute changes of 1 microstrain, meeting the precision requirements for bridge monitoring. Secondly, it has strong anti-interference ability and is not affected by electromagnetic environment, making it particularly suitable for use on Bridges near high-voltage transmission lines. The third advantage is its excellent durability. It adopts an all-optical fiber structure and can resist the influence of harsh environments such as moisture and corrosion. The last aspect is the distributed measurement capability. A single optical fiber can be connected in series with dozens of sensors, greatly simplifying the wiring difficulty.

In specific application scenarios, the FBG system can accomplish multiple important monitoring tasks. Long-term health monitoring is the most important application. By deploying sensor networks at key parts of the bridge, continuous tracking of the structural status can be achieved. Load test monitoring is another important application. The high sampling frequency characteristic of FBG makes it particularly suitable for data acquisition in bridge dynamic load tests. In terms of special event monitoring, the FBG system can record the structural responses under extreme events such as earthquakes and strong winds. In addition, during the process of bridge maintenance and reinforcement, FBG sensors can monitor the impact of construction on the structure in real time.

From the perspective of technical implementation, a complete FBG bridge monitoring system consists of three main components. The sensor network is responsible for data collection and is usually optimally arranged according to the structural characteristics of the bridge. The data acquisition system realizes the demodulation and storage of signals. Modern systems mostly adopt modular design. The data analysis platform is responsible for data processing and early warning. More and more systems are beginning to introduce artificial intelligence algorithms for intelligent diagnosis.

At present, FBG bridge monitoring technology is developing in several directions. First of all, the application of wireless transmission technology has solved the problem of complex wiring in traditional wired systems. Secondly, there is the in-depth application of intelligent algorithms to improve the accuracy of damage identification through machine learning. The third is the integration with other monitoring technologies, such as forming a multi-source monitoring system with GNSS, inclinometers, etc. The last aspect is the in-depth utilization of monitoring data. By integrating with BIM technology, it provides data support for the digital twin of Bridges.

There have been numerous successful application cases at home and abroad. For instance, the Hong Kong-Zhuhai-Macao Bridge has adopted a large-scale FBG monitoring system, achieving comprehensive monitoring of super-long cross-sea Bridges. The cable force monitoring system of the Golden Gate Bridge in the United States also adopted FBG technology. FBG monitoring systems have been deployed in many large cable-stayed Bridges and suspension Bridges in China, accumulating rich engineering experience.

In the future, with the advancement of technology, the application of FBG in bridge monitoring will become more in-depth. The new packaging process will enhance the environmental adaptability of sensors. The application of 5G technology will improve the efficiency of data transmission, and the development of artificial intelligence will enhance the ability of data analysis. These technological advancements will enable the FBG system to play a greater role in bridge safety early warning, life prediction and other aspects.