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

• Published in: Composite structures 2022-11, Vol.300, p.116106, Article 116106
• Main Authors: Jahani, Younes, Baena, Marta, Codina, Alba, Barris, Cristina, Torres, Lluís
• Format: Article
• Language: English
• Subjects: Long-term load; NSM FRP-strengthening; Service temperature; Time-dependent deflections
• ISSN: 0263-8223; 1879-1085
• DOI: 10.1016/j.compstruct.2022.116106

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 °C) 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.