Time-dependent behavior of NSM CFRP-strengthened RC beams under different service temperatures

The use of fiber reinforced polymer (FRP) for flexural strengthening of reinforced concrete (RC) beams has become a popular strengthening technique. Significant amount of work is available on the short-term flexural behavior of RC beams strengthened with near-surface mounted (NSM) technique. However, their time-dependent flexural behavior, specifically under high service temperature, has not yet been addressed. This paper presents an experimental work to evaluate the time-dependent behavior of NSM carbon FRP (CFRP)-strengthened RC beams. The experimental program included 23 beams, where the effect of different parameters such as strengthening (CFRP) area, steel reinforcement ratio and applied temperature (20 and 50 ?) have been considered. Experimental results show that the effect of strengthening area is significant on the flexural short-term response of the beams, while minor effects are found on the time-dependent deflections. On the other hand, increasing the service temperature has no significant effect on the short-term tests, but it produces a large increase in the time -dependent deflection of the specimens. Finally, an analytical procedure for the prediction of time-dependent deflections, which is based on the age-adjusted effective modulus method (AEMM), is presented. Good agreement between the experimental results and analytical predictions on time-dependent deflections is shown.