Existing and potential solutions for fire-resistance of FRPjacketed concrete columns

The application of fiber reinforced polymer (FRP) in structural rehabilitation is sometimes challenged or opposed by engineers and building authorities due to the suboptimal thermal performance of FRP material, along with many code limitations (e.g., system critical temperature). Compared with other mechanical and durability behaviors, fewer studies have been conducted on the effect of elevated temperatures on FRP-related structures. The dilemma of the inadequacy of FRP schemes under thermal/fire conditions could be summed up in two categories: (1) structural and (2) environmental concerns. A thorough investigation of the behavior under fire loading is crucial to understand FRP’s inadequate bonding properties and the degradation of its mechanical performance at elevated temperatures, along with the accompanying generation of fumes, smoke, and toxic gases. This paper presents a short but comprehensive review of the existing tests on the fire performance of FRP-jacketed concrete columns. The FRP confinement, as well as bond, under high temperatures, are reviewed and discussed. FRP schemes typically lose their integrity and bond once the temperature exceeds matrix glass transition temperature (Tg )(typically 65 °C~140 °C), as shown in Figure 1. The Assessed solutions include system neglect, matrix replacement, and providing passive fire protection. Based on the test results reviewed and relevant mechanisms discussed, a potential novel solution for fire resistance of FRP-jacketed concrete columns is proposed in this paper. The idea of the potential solution is to use mechanical anchoring technology to prevent FRP-concrete debonding to enhance the fire performance of FRP-jacketed concrete columns. Recommendations for future work in this area are presented.