Steel structure is a non combustible building material with characteristics of earthquake resistance and bending. In practical application, steel can not only relatively increase the bearing capacity of buildings, but also meet the needs of architectural design and aesthetic modeling, and avoid the defects of building materials that cannot be bent and stretched. Therefore, steel is popular in the construction industry. Steel is used in single storey, multi-storey, skyscrapers, sites, warehouses, waiting rooms and waiting rooms. However, as a building material, steel has some inevitable defects in fire prevention. Its mechanical properties, such as yield point, tensile strength and elastic modulus, will drop sharply with the increase of temperature. The steel structure usually loses its bearing capacity at the temperature of 450 ~ 650 ° C, and large deformation occurs. The steel column and beam bend, resulting in excessive deformation and can not be used again. Generally, the fire resistance limit of unprotected steel structure is about 15 minutes. The length of this time is also related to the heat absorption speed of the components. In order to overcome the shortage of fire prevention in practical application of steel structure materials, fire prevention treatment must be carried out. The purpose is to raise the fire resistance limit of the steel structure leased on site to the limit range specified in the design specifications. There are various measures to prevent the steel structure from rapidly heating up and deforming in fire, and it is important to take different methods according to the situation. For example, heat insulation and refractory materials are used to prevent the flame from directly burning the steel structure, reduce the heat transfer rate, and delay the time when the temperature of the steel structure rises and the strength becomes weak. But no matter what method is used, the principle is the same. Therefore, the author believes that in reality, we must pay attention to four kinds of fire protection measures for steel structures.

First, the outsourcing layer. As the name implies, it is to add an outer coating on the surface of the steel structure for spraying construction. Jinma steel structure fire-proof slurry (single component) is coated on the steel structure surface with special coating equipment to form a protective layer. The thickness of the fire-proof slurry can be designed according to the fire-proof requirements, meeting the fire resistance limit of more than 2-3 hours. It is a fire-proof slurry with good performance and high cost performance in the market at present.

Second, water filled jacket. Water filling of hollow steel structure is the most effective protection measure against fire. This method can keep the steel structure at a low temperature in case of fire, and the water circulates in the steel structure to absorb the heat of the material itself. The hot water can be recycled after cooling, or cold water can be introduced into the pipeline to replace the hot water.

Third, shielding. The steel structure is set in the wall and ceiling made of refractory materials, or the components are wrapped in the gap between the two walls. As long as a small amount of refractory materials are added or not added, the purpose of fire prevention can be achieved. This is the most economical fire prevention method.

Fourth, expansive materials. The steel structure fireproof coating is used to protect the components. This method has the advantages of good fire and heat insulation performance, and construction is not limited by the geometry of the steel structure. Generally, there is no need to add auxiliary facilities, the coating is light in weight, and has a certain aesthetic and decorative effect. It is a modern and advanced fireproof technical measure. At present, there are more and more high-rise steel structure buildings, especially some super high-rise buildings, which adopt steel structure more widely. Once a fire accident occurs in a high-rise building, the fire cannot be extinguished in a short time, which requires us to strengthen the fire protection of building materials in building design to enhance their fire resistance limit, and formulate necessary emergency plans inside the building to reduce casualties and property losses.