Steel is a non-combustible building material, which has the characteristics of earthquake resistance and bending resistance. In practical applications, steel can not only increase the load capacity of buildings relatively, but also meet the needs of architectural design aesthetics, and avoid the defects of concrete and other building materials that cannot be bent and stretched. Therefore, steel has been favored by the construction industry. , Single-story, multi-story, skyscrapers, factories, warehouses, waiting rooms, waiting halls, etc. are all made of steel. However, as a building material, steel has some unavoidable defects in fire prevention. Its mechanical properties, such as yield point, tensile strength and elastic modulus, will drop sharply due to the increase of temperature.
Steel structures usually lose their bearing capacity at a temperature of 450~650°C, and undergo a large deformation, resulting in bending of steel columns and beams. As a result, they cannot continue to be used due to excessive deformation. The limit is around 15 minutes. The length of this time is also related to the speed at which the component absorbs heat. In order to overcome the deficiencies in fire protection of steel structure materials in practical applications, fire protection treatment must be carried out, the purpose of which is to increase the fire resistance limit of steel structures to the limit range specified in the design code. There are various measures to prevent the steel structure from rapidly heating up and causing deformation and collapse in a fire. The key is to adopt different methods according to different situations, such as using heat insulation and refractory materials to block the flame and directly burn the steel structure to reduce the speed of heat transfer. Delay the temperature rise of steel structure, the time of strength weakening, etc.
