Development and practical application of fire-resistant steel for buildings

In steel-frame buildings, steel members should be protected by spraying fire-resistant materials so as not to be heated to higher than 350 °C during fires. The work of spraying fire-resistant materials, however, has an injurious effect on the workers' health and is a time-consuming job. In addition, the usable space of the building is reduced by such fire-resistant coating. Therefore, there has been an increasing demand for restricting fire-resistant coatings. The development of fire-resistant steels for buildings was aimed at increasing steel's elevated-temperature strength while assuring earthquake resistance, weldability and other properties equal to or better than those of conventional steels for buildings. This paper first describes fundamental studies made of the effects of alloying elements and manufacturing conditions on elevated-temperature strength, and then presents the development of a fire-resistant steel which provides high strength at 600 °C while ensuring good earthquake resistance and weldability.