Fire resistance rating of lightweight steel structural panel houses
Thread Content
Many companies these days use workshop structures in the style of steel-frame sheds, with steel structures providing the load-bearing capacity and colored steel plates applied on the exterior; there are also parapets at the bottom, which can be at different heights. How is the fire resistance rating of such buildings determined? The new construction regulations do not specify the fire resistance limit for materials like colored steel plates, and some people who have searched online say it is around 15 minutes. What fire protection rating can such buildings achieve?
1. If it is ordinary foam filling, it is not fireproof. 2. If the filling material is rock wool, it can achieve Class A fire resistance.
Color-coated steel sheets are classified by substrate into cold-rolled substrates, hot-dip galvanized substrates, and electro-galvanized substrates； Based on their structure, they are divided into single-layer color steel plates and sandwich color steel plates. The core materials used in sandwich color steel plates are generally polyurethane, polystyrene, or rock wool. The ignition point of polyurethane is around 130°C, similar to that of ordinary paper. The ignition point of polystyrene is 346°C, only slightly higher than that of wood; both of these fillers are flammable materials ； Rock wool is an inorganic material with a burning point of around 1000°C; it is considered a non-flammable material. For the core material of sandwich color steel panels, insulation materials with a fire resistance rating of Class A should be preferred, and insulation materials with a fire resistance rating lower than Class B2 should not be used. When insulation materials of Class B1 or B2 are used, flame-retardant treatment measures must be applied. In construction, core materials for sandwich color steel panels should preferably be those with flame-retardant properties and a Class A fire performance, such as rock wool and glass wool; the use of foam-based color steel panels made from polyurethane, polystyrene, and similar materials should be completely prohibited. In construction, the advantages of color steel plates – such as their light weight and thermal insulation properties – need to be utilized. When used as building components, in addition to the core material of these plates meeting the required combustion performance standards, the base layer of the color steel plates must also be treated to be fire-resistant, so as to meet the fire resistance requirements for building components in structures of certain fire resistance ratings. When color steel plates are used as partition walls in buildings with a secondary fire resistance rating, it is required that the combustion performance of their core material be grade A; after fire protection treatment of the base plate, its fire resistance limit must not be less than 0.5 hours ； When used as partition walls on both sides of evacuation corridors, the fire resistance rating must not be less than 1.0 hour.
The problem is that the factory building in question consists of just one layer of color-coated steel sheet; it is necessary to determine its fire resistance rating in order to establish a safe distance from the Class A liquid storage area
15 minutes is 0.25 hours, which meets the requirements for a fire resistance rating of level 4