Long-term Behavior of Reinforced Concrete Beams Flexurally Strengthened with FRP Strip

Soo Yeon Seo, Hi Van Tran, Kang Su Kim, Hyun Do Yun, Gun Cheol Lee

Research output: Contribution to journalArticlepeer-review


The purpose of this study is to evaluate the long-term behavior of RC beams reinforced by fiber reinforced polymer (FRP) strip such as near-surface mounted retrofit (NSMR) and externally bonded retrofit (EBR). The 30% loads of nominal strength of the RC beams were applied and continued for up to 49 days. The loads were increased up to 55% of the nominal strengths of RC beams at 50 days after performing flexural retrofit by using FRP with the planned retrofit methods and have been kept for almost one year. During all loading periods, the deflections and the strains of rebars and FRPs were measured at least once every week. The long-term behavior of all specimens was evaluated and the deflection variations were predicted by considering the long-term effect on the nonlinear sectional analysis result of the reinforced RC beams. As a result, in the specimen reinforced with partially de-bonded NSM FRP, the strains of the FRP strip were not concentrated on the center of the beam and the magnitude at the center was less than that with the fully bonded FRP. In addition, it is possible to properly simulate the deflections of the beams strengthened with FRP exposed to a long-term load by considering the long-term effect on the sectional analysis result.

Original languageEnglish
Pages (from-to)231-238
Number of pages8
JournalJournal of the Architectural Institute of Korea
Issue number3
StatePublished - Mar 2023


  • Deflection
  • Externally Bonded Retrofit (EBR)
  • Fiber reinforced polymer (FRP) strip
  • Flexural retrofit
  • Long-term Behavior
  • Near-surface-mounted Retrofit (NSMR)


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