What are the methods to improve the fire resistance of steel structures?

Steel structures commonly used in the construction industry have many advantages, such as light weight, recyclable materials, etc. However, because the steel itself cannot withstand the characteristic high temperature, the safety of steel structure buildings is affected, and the development of manufacturers is hindered.

1. The general steel used for building fire resistance and weathering steel has poor fire resistance, but by changing the material composition of steel, adding specific components, and changing the structure and microstructure of steel, the fire resistance and weather resistance of steel itself can be improved. This is fire resistance and weathering steel. When the temperature of this steel reaches 600℃, the strength decreases by less than 30%. In addition, due to its good fire resistance, the thickness of the protective layer can be appropriately reduced during the construction process, or even no anti rust paint can be applied, which can save some costs. The application of fire and weather resistant steel is a fundamental policy and should be vigorously promoted.

2. The fire resistance of pure steel structures and components with strong fire resistance is relatively poor, but they can be properly combined with concrete to form composite components, or reinforced concrete structures can be directly used in some key parts. For example, concrete filled steel tubular columns can be used as columns, which can effectively improve the fire resistance limit. The larger the steel pipe diameter is, the longer the fire resistance time is. The circular steel tube concrete column with a diameter of 500mm is coated with 15mm thick thermal insulation and fire retardant coating, which can meet the fire resistance time of 3 hours. However, the reinforced concrete structure should be used as far as possible for the components with high fire resistance requirements, such as floors, stairs, etc.

3. Adopt reasonable fire protection structure treatment scheme for steel members. The fire protection structure of steel structure shall be reasonable, firm, economical, easy to construct and conducive to decoration. When the enclosure or partition member with incombustible body is on the same axis with the steel member, the incombustible wall itself can be used to provide fire protection for the steel member, without the need for a fire layer. For exposed steel members, reasonable fire prevention measures shall be taken.

4. Implement effective fire prevention methods. The commonly used fire protection methods for steel structures include concrete protection, reinforcement mesh cement mortar, fire-proof board and fire-proof coating. Wrapped concrete protection means that steel members are completely wrapped by concrete, and structural reinforcement shall be arranged in concrete to prevent concrete from falling off. Steel mesh cement mortar fire prevention is a traditional construction method, which uses metal mesh plastering 50 # mortar as the protective layer. The fireproof board can be used to wrap the steel members with non combustible materials such as fiber reinforced cement board, gypsum board, calcium silicate board, vermiculite board, etc.

The fire resistance of steel structure depends on steel, which is incombustible and has good heat resistance. Based on the physical characteristics of steel, green building structures have become quite popular in developed countries. Do not let the fire resistance hinder the manufacturer. Effective measures should be taken to improve the fire resistance of steel structures and speed up their development.