Structural Health Monitoring (SHM) is defined as the use of on-site non-destructive sensing technologies to investigate and analyze the location and extent of structural damage by analyzing structural system characteristics including structural responses, thereby detecting structural damage or degradation. With the development, complex building structures such as long-span, deep-basement, and super-high-rise buildings have sprung up. Today, many buildings are facing aging and failure problems. How to detect the health status of aging buildings and conduct comprehensive monitoring of normally operating buildings has become an urgent problem to be solved in the industry. Active, real-time, and effective health monitoring of building structural conditions helps evaluate safety status and predict service life. As a new type of sensor, optical fiber sensors have irreplaceable advantages in complex civil engineering structures: small size, light weight, and flexibility; they can be embedded inside concrete structures, are corrosion-resistant, high-temperature-resistant, and radiation-resistant; they can work in harsh environments for a long time, are anti-electromagnetic interference, and have stable signals, ensuring true and reliable measurement results. The high-precision distributed optical fiber sensing system (OSI) provides unprecedented spatial resolution, enabling blind-zone-free acquisition of test data at various locations and offering reliable and accurate data for strain/temperature fields. The high-speed fiber Bragg grating demodulator (FBGS) provides sampling speeds at the level of tens of kilohertz, capturing transient change data. The microstructure fiber distributed acoustic sensing system (MS-DAS) offers measurement lengths at the level of tens of kilometers, ultra-high sensitivity, and detection frequency bands, enabling the acquisition of distributed and comprehensive vibration signals.

• Structural Deformation Monitoring / Building Structure Monitoring Key building structures are the core of the entire building system and bear the main load-bearing work, such as pile foundations, supporting beams, load-bearing columns, etc. Under special climatic and operational conditions, key structural components may suffer from extremely serious abnormalities such as deformation, displacement, and cracking, and these damages are extremely fatal to the entire building system. Timely and effective monitoring of the health status of key structures, and providing basis and guidance for building structure maintenance, repair and major decision-making based on monitoring data, can effectively prevent the occurrence of major accidents.

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• Application of OFDR in Deformation Monitoring of Special-shaped Steel Sheet Piles Bridge Online Monitoring OFDR-based Quantitative Monitoring of Vertical Staggered Deformation of Discontinuous Pipelines High-precision Measurement of Deformation of Cast-in-place Pile Shafts Shield Tunnel Segment Monitoring Based on OFDR Distributed Optical Fiber Sensors

• Crack Identification and Early Warning Crack issues in concrete structural components are unavoidable key problems in civil engineering construction and operation. Harsh environments and external loads can cause cracks in building structures. These cracks will gradually deepen and widen over time until structural failure occurs. Early monitoring of cracks ensures timely repairs and avoids irreversible damage. Distributed optical fiber sensing technology can accurately locate crack positions and measure crack widths, which is of great significance for evaluating the safety status of concrete structural components.

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• Application of OFDR in Geotechnical Laboratories Crack Detection of Reinforced Concrete Beam Structures Concrete Crack Identification and Monitoring Based on OFDR Technology

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  Soil Health Monitoring Whether constructing transportation facilities, building large-scale structures, or preventing natural disasters, it is necessary to study the performance and health status of soil infrastructure. The analysis and evaluation of soil structure stability have become core content in civil engineering. Qualitative analysis of complex soil structures is a direction continuously explored and researched by numerous scholars, and ensuring the timeliness and accuracy of test results has become a monitoring difficulty. As a new type of sensor, optical fibers have advantages such as corrosion resistance, anti-electromagnetic interference, and high sensitivity, making them highly advantageous for soil health monitoring.

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• OFDR for Optical Cable-Soil Coupling Strain Monitoring OFDR for Soil Compression Deformation Monitoring