Moisture diffusion in glass–fiber-reinforced polymer composite bridge under hot/wet environment

In literatures, researches on degradation of composites due to environmental effects were well documented on fiber-reinforced polymer (FRP) composites for Aerospace Engineering; for FRP composites utilized in Civil Engineering field, the available information was very limited. In order to keep pace with the application of FRP composites in Civil Engineering field, this research was undertaken to reveal more knowledge about the environmental degradation of FRP composite bridge under hot/wet environment. By gravimetric experiments, the moisture diffusion in thin-section of FRP composites and adhesives were characterized. Based on the analytical model of one-dimensional moisture diffusion theory, the diffusion coefficients were determined by the best least-square curve fitting to the experimental data. The finite element (FE) models of test specimens were developed and validated against experimental results. Through transient FE diffusion analysis, the moisture diffusion into the FRP-steel composite bridge deck system under a hot/wet environment was numerically predicted up to 100-year aging duration. The moisture uptake in adhesive connection was fully saturated after 26-year aging. The area between FRP composite sections and the adhesive layer was confirmed to be the most sensitive part to moisture effects. This research developed a step towards the prediction of long-term performance and life-time estimation of FRP-steel composite bridges.