Steel bar is a non-combustible building material that is shock and bending resistant. In practical applications, steel can not only increase the load capacity of buildings, but also meet the needs of architectural design aesthetics. It also avoids the defects that concrete and other building materials cannot bend and stretch. Therefore, steel is favored by the construction industry. Steels used in single-storey, multi-storey, skyscrapers, factories, warehouses, waiting rooms, and waiting rooms are common. However, steel as a building material has some inevitable defects in fire protection, and its mechanical properties, such as yield point, tensile strength and elastic modulus, will drop sharply due to the increase in temperature.
    
    Steel structures usually lose their load carrying capacity at temperatures of 450 to 650 ° C, causing large deformations, resulting in bending of steel columns and steel beams. As a result, they cannot be used due to excessive deformation. Generally unprotected steel structures are fire resistant. The limit is about 15 minutes. The length of this time is also related to the speed at which the component absorbs heat.
    
    In order to overcome the fire prevention deficiencies of steel structural materials in practical applications, fireproof treatment must be carried out, the purpose of which is to increase the fire endurance of the steel structure to the limits specified by the design specifications. Preventing steel structures from rapidly heating up in a fire and causing deformation and slumping. The measures are various. The key is to adopt different methods according to different situations, such as using adiabatic 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 the steel structure and the time when the strength is weakened. But no matter what method is adopted, the principle is the same.