With the continuous progress of modern economy, the construction of cities is not backward. With the booming of high-rise buildings and the rise of building height, more and more people begin to pay attention to steel structure, because steel structure building has many advantages, such as high strength, light weight, good seismic performance, short construction period, low foundation cost, less occupied area of structure and high degree of industrialization. However, compared with the concrete structure, the steel structure is easy to conduct heat. When the steel surface temperature reaches more than 400 ℃, its strength and modulus of elasticity will decrease significantly. When the temperature reaches 600 ℃, the strength of steel structure is almost zero. The fire resistance limit of bare steel is usually only 15-30 minutes. According to the requirements of the code for fire protection design of buildings in China, the fire resistance limits of the main load-bearing components of buildings, such as columns, beams, walls and floors, are respectively 0.5-3.0 hours. Our country has stipulated that fire prevention measures must be taken in steel structure, and must meet the corresponding national standards to pass the acceptance.
There are many fire prevention methods for steel structure. In the past, it used to adopt the methods of cast-in-place solid concrete outer layer, setting fire barrier with firebrick, covering with gypsum board or cooling with water filling inside hollow pipe. Now more is to use spray fire-proof coating, anticorrosive coating, fluorocarbon paint to protect steel structure. Because of its good fire and heat insulation performance, the construction is not limited by the structure geometry, generally does not need to add auxiliary facilities, and the coating is light in weight, and has a certain role of aesthetic decoration, so it has been widely used.