Analyzing environmental effects on the mechanical performance of composite reinforcement systems

Abstract

In recent years, fiber-reinforced polymeric (FRP) materials have become promising alternatives to steel because of their lightweight, electromagnetic transparency, and corrosion resistance. However, the unfavorable environment (elevated temperature and high humidity in particular) can affect the long-term mechanical performance of these materials. Therefore, this study utilizes the previously developed testing layout and analytical model to simulate and quantify these unfavorable effects in concrete beams reinforced with FRP composites. The explicit analytical model quantifies the flexural stiffness reduction expressed in the equivalent stresses acting on the tensile concrete. This approach does not require specifying the loading history that makes it feasible for the comparative analysis of the stiffness degradation of FRP-reinforced concrete via a series of repeated mechanical tests corresponding to continuous exposition to the harsh environment. This study considers the open atmosphere corresponding to the Nord Europe climatic region. In addition, after applying the service load, the reference specimens were kept under laboratory conditions. The latter samples provide the reference for quantifying the stiffness degradation and the repeated mechanical load effect expressed in the residual deflection of the test sample. Thus, this study reveals that the open environment specifically affected the stiffness decay in the external bonded reinforcement system. In contrast, this effect in the near-surface mounted reinforcement system was insignificant.