FRP-strengthened RC beams under sustained loads and weathering

Glass FRP-strengthened RC beams were subjected to sustained loads and placed for different periods outdoors, indoors, and in chambers that accelerate the effects of outdoor tropical weathering by a factor of six. Beams subjected to outdoor weathering had up to 18% larger crack widths and 16% larger deflections compared to those kept indoors at the end of 1 and 2¾ years, respectively. The increase in deflections and crack widths was lesser for beams with a higher FRP reinforcement ratio. The residual flexural strength and ductility of the beams decreased with longer weathering periods. Also, the failure mode of the beams changed from concrete crushing to FRP rupture, indicating a deterioration in the mechanical properties of the FRP laminates. Analytical methods which account for material degradation in concrete and FRP laminates are presented and found to predict the long-term flexural characteristics of the beams well.