Structural fire design of ear strengthened RC beams

This paper discusses the structural fire design of reinforced concrete beams strengthened in flexure by means of externally applied reinforcement (EAR). It is focusing on the Eurocode approach for fire rating of individual members. Three different fire safety approaches are presented, depending on the strengthening ratio. Applicability of fire design methods, such as the use of the tabulated data and 500°C isotherm methods by EN1992-1-2, is indicated. Results show the importance of a well thought approach in the structural fire design of EAR, being a popular strengthening technique for concrete members. Through this strengthening solution, the load bearing capacity of existing members is strengthened or retrofitted, both in service conditions and at ultimate limit state. The EAR strengthening relies on a good bond interaction between the existing member and the externally applied reinforcement. However, given the weak properties of the bond interface at elevated temperatures, the fire performance is of special concern in the structural design of EAR strengthened reinforced concrete.