A comparison of the mechanical properties of fire-resistant and S275 structural steels

The mechanical properties of two fire-resistant (FR) structural steels and an S275 steel have been investigated from room temperature up to 700 degrees C, with the aim of assessing the viability of FR steels. The major focus has been on the tensile and creep properties of the steels at high temperature and the effect of these properties on the fire resistance of model steel beams. It has been found that the FR steels performed significantly better than the S275 at high temperature, retaining 50% of their room temperature strength at a temperature of approximately 650 degrees C. The S275 steel retained 50% strength to a temperature of 550 degrees C, this being consistent with literature values. In creep tests carried out at 600 degrees C, the FR steels also exhibited lower maximum strains and strain rates than the S275. The improved strength reduction factors led to a significant increase in fire resistance for a model steel beam with various floor slab configurations, showing that FR steels can become a practical alternative to conventional structural steels. (C) 1999 Elsevier Science Ltd. All rights reserved.