Performance-based approach for fire resistance design of FRP-strengthened RC beams: A case study

The use of externally bonded fiber-reinforced polymer (FRP) systems in the strengthening of reinforced concrete (RC) members has become widely accepted in practice in recent years. A significant concern with this strengthening technique is the fire resistance of the strengthened member, for which a reliable design approach has not been developed. This paper presents a newly established design approach for the fire resistance of FRP-strengthened RC beams and demonstrates its use through a case study. The proposed approach allows the use of three different levels of fire insulation following the performance-based design philosophy. In a Level-I design, no fire insulation is provided and the mechanical resistance of the FRP system is completely ignored; the RC beam itself is expected to survive the required fire resistance period. On the other extreme, a Level-III design can be adopted, in which the FRP system (as well as the original RC beam) is protected by fire insulation to remain effective during the required fire resistance period. Between the two extremes, a Level-II design can be employed, in which a moderate level of fire insulation is provided to protect the RC beam rather than the FRP system. For each level of design, appropriate methods of analysis are introduced for fire resistance evaluation. All three levels of fire resistance design are illustrated in the paper through a case study.