Behavior of CFRP-Prestressed Concrete Beams under Sustained Load at Low Temperature

The behavior of precast concrete beams prestressed using carbon fiber-reinforced polymer ( CFRP) rods was studied under the combined effects of sustained load and low temperature. Three 13-year-old concrete T-beams were tested, including two with CFRP rods stressed to different levels and one with steel prestressing strands. Test beams were exposed to -27 degrees C while being subjected to a sustained load of 25% of their flexural strength for 163 days. The sustained load was equivalent to the service load level and produced cracking in two of the beams with the lower prestress levels. Results were then compared to those obtained from a set of similar beams subjected to the same sustained load at room temperature. Deflection increase under sustained load at low temperature was generally small and similar to that at room temperature. Prestressing strain decreased as the temperature decreased in the CFRP-prestressed beams. Exposure to low temperature likely contributed to a 19% reduction in strength and a change in failure mode from flexure to bond failure. DOI: 10.1061/(ASCE)CR.1943-5495.0000045. (C) 2013 American Society of Civil Engineers.