Influence of concrete cover on fire resistance of reinforced concrete flexural members

Six specimens with different concrete cover (CC) thickness (10-30 mm) were tested to investigate the influence of the CC on the properties of reinforced concrete flexural members exposed to fire. The specimens were heated on their bottom and two lateral surfaces. From these test results, it is shown that the bottom CC has significant influence on the specimen ultimate loading capacity, but the extent of this influence will decrease with an increase in the CC thickness. Thus, it is improper to excessively increase the bottom CC thickness to improve the specimen fire resistance. The lateral CC has a less beneficial effect on the specimen fire resistance compared to the bottom CC. A concept of the equivalent CC thickness is proposed in this paper to better predict the effect of the CC on the flexural capacity of reinforced concrete members exposed to fire.