FIRE ENDURANCE OF INSULATED NSM FRP STRENGTHENED BEAMS

摘要

The structural behaviour of fiber reinforced polymer (FRP) strengthened members can be critical under fire exposure. Of constituent materials, the fibers in FRP materials perform significantly better at elevated temperatures than the polymer binder of these composites. The polymer adhesives (ambient cured epoxies) currently used as primers, adhesive and matrixes for FRP soften at temperatures in the range of their glass transition temperature and consequently their integrity can be lost during fire. In order to evaluate the behaviour of FRP strengthening systems under fire exposure an investigation was set-up to examine and document the performance under fire exposure to full scale near-surface mounted (NSM) FRP strengthened concrete beams. Different types of insulation materials (boards and coatings), configurations and thicknesses were investigated. The specimens were exposed to a standard fire while submitted to their service load. Test results indicate that insulated NSM FRP strengthened beams can achieve a satisfactory fire endurance of at least two hours, though contribution of the FRP is generally lost earlier. The proposed paper also discusses residual strength tests on fire tested beams, tested at room temperature up to failure. Results of this study suggest that if the insulation system is able to maintain the adhesive temperature at temperature below or moderately above the glass transition temperature, the FRP concrete bond degradation under fire is limited and the FRP strengthened beam is still able to retain part of the original strength.