PSI - Issue 64

Mingyang Xi et al. / Procedia Structural Integrity 64 (2024) 515–522

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Author name / Structural Integrity Procedia 00 (2019) 000 – 000 5 force conversion curve (Fig. 5.) and coefficient (Table. 3) for each self-sensing strand can be calculated. With the raw data obtained after preprocessing, the calibration curve for each self-sensing strand can be established, and the relationship between force value and wavelength change can be formulated. The monitoring scheme includes the use of a fiber Bragg grating interrogator, whose performance indicators meet the strict requirements for environmental testing and wavelength deviation. The fiber Bragg grating interrogator provides the necessary data analysis and reading capabilities during the monitoring process, offering technical support for the monitoring.

3. Self-sensing Strand Engineering Application Analysis

3.1. Engineering Background This project is located in southern China and represents a significant effort to enhance the region's transportation infrastructure. The engineering route spans a total length of 16.476 kilometers and consists of a highway bridge that connects multiple towns and cities. In this context, bridges serve as crucial transport-bearing structures, where durability and stability in complex environments are essential. Traditional bridge structures often utilize steel materials and conventional strands as prestressing tendons. Although these materials can meet basic stress requirements, they are incapable of providing long-term effective monitoring of the stress state during bridge operation, thereby increasing maintenance costs and imposing an economic burden on operating entities.

Fig. 6. Project Construction Site In response to the aforementioned challenges, this project proposes the use of multiple self-sensing strands within the bridge structure. While maintaining the original overall performance of the bridge, the embedding of fiber-optic sensing in self-sensing strands enables the dual function of load bearing and sensory perception for the prestressing strands, providing support for the intelligent operation and maintenance of the bridge structure. To effectively monitor the loss of prestress during the service period after replacing with carbon fiber strands, self-sensing strands were arranged in 5 beams within one span of the bridge (Fig. 7.), totaling 5 self-sensing strands. The self-sensing strands also use high-strength, low-relaxation prestressed strands that conform to the GB/T 5224-2014 standard, with a nominal diameter of 15.2mm, nominal area of 140mm², f pk = 1860Mpa, E p = 1.95GPa, and the design tension control stress of 0.75 f pk = 1395MPa. The application of this research aims to solve the technical challenges of health monitoring during the operation period of bridges with prestressed self-sensing strands, expected to bring significant economic and social benefits, and lay a solid foundation for bridge development. The application of this technology is the first of its kind globally, representing a leading international research and engineering achievement.