Development of the fire-protective system (membrane system) using fire-resistant steel for cooperative houses

Fire-resistant steel for building structure (FR Steel) is the one whose high-temperature intensity is improved by adding alloy elements (e.g. molybdenum) with heat-resistance enhancing ability. At 600 deg C, the steel has a yield point over 2/3 of the specification value at room temperature, which is long-term permissible stress. On the other hand, a fire temperature reaches about 1,000 deg C in the case of a fire in a building with a lot of inflammables such as a house, therefore, applying FR steel to this kind of building could not omit insulating shield, rock wool for example. With cooperative houses as our target, we have developed steel-framed construction using FR steel without fire-resistant shield and its fire-resistance designing method, which makes use of the thermal insulation effects of the interior materials (walls and ceilings).