Long-Term Performance Evaluation of an FRP Composite Road Bridge Using DFOS Monitoring System

FRP composite bridges have been in operation since the mid-1990s, allowing for the evaluation of their long-term behaviour. Many of the early FRP bridges in the USA and Western Europe were equipped with monitoring systems to assess their structural integrity after years of use. In Poland, the first all-FRP composite bridge was also equipped with a modern structural health monitoring (SHM) system based on distributed fibre optic sensing (DFOS) to enable long-term performance monitoring. Over nearly a decade of use, the bridge’s strain, stiffness, and dynamic properties have been evaluated three times through static and dynamic load tests. Research findings indicate that the bridge has maintained satisfactory structural integrity and durability over an eight-year operational period. However, the quality of the adhesive joints between the girders and the deck panels was found to be inadequate, resulting in a slight decrease in the bridge’s performance, specifically in stiffness and dynamic characteristics. Fortunately, these negative changes did not compromise the bridge’s safety or serviceability, as stipulated by the design requirements. An effective repair was completed, restoring the bridge to its full operational efficiency.