Structural fire design of ear strengthened RC beams

摘要

This paper discusses the structural fire design of reinforced concrete beams strengthened in flexureby means of externally applied reinforcement (EAR). It is focusing on the Eurocode approach forfire rating of individual members. Three different fire safety approaches are presented, dependingon the strengthening ratio. Applicability of fire design methods, such as the use of the tabulated dataand 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, beinga popular strengthening technique for concrete members. Through this strengthening solution, theload bearing capacity of existing members is strengthened or retrofitted, both in service conditionsand at ultimate limit state. The EAR strengthening relies on a good bond interaction between theexisting member and the externally applied reinforcement. However, given the weak properties ofthe bond interface at elevated temperatures, the fire performance is of special concern in thestructural design of EAR strengthened reinforced concrete.