December 2009
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This paper discusses the behaviour of normal and high strength concrete beams exposed to elevated temperature. The paper also provides a simple, economical, and reliable technique that can be used to assess the fire resistance of concrete beams exposed to multi-action of external loads and elevated temperature simultaneously. The new technique was verified by testing (36) normal and high strength concrete beams made of concrete mixes of different w/c and s/c ratios. The tested beams comprised simply supported and restrained beams, anti-fire coated beams, and beams cooled by different methods. The results showed that the presented technique is effective and succeeded to distinguish among the different RC beams. The results also indicated that testing RC beams subjected to flexural load and then exposed to elevated temperature provided better understanding to the structural behaviour of the flexural elements in the field. The results also showed that the restrained RC beams exhibited better fire resistance when compared to the simply supported RC beams. Using of anti-fire resisting coating improves the fire resistance of RC beams made of high strength concretes. The results also emphasised on involving the influence of the cooling methods to evaluate the actual behaviour of the flexural elements.