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 degree s 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 temperat ure and the effect of these properties on the fire resistance of model stee l beams. It has been found that the FR steels performed significantly bette r than the S275 at high temperature, retaining 50% of their room temperatur e strength at a temperature of approximately 650 degrees C. The S275 steel retained 50% strength to a temperature of 550 degrees C, this being consist ent with literature values. In creep tests carried out at 600 degrees C, th e 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 configur ations, showing that FR steels can become a practical alternative to conven tional structural steels. (C) 1999 Elsevier Science Ltd. All rights reserve d.