It also avoids the defects of concrete and other building materials that cannot be bent and stretched. Therefore, steel is favored by the construction industry. Steels used in single-story, multi-story, skyscrapers, factories, warehouses, waiting rooms, and waiting rooms are very common.

However, steel as a building material has some unavoidable defects in fire protection, and its mechanical properties such as yield point, tensile strength and elastic modulus will drop sharply due to temperature rise.

The steel structure usually loses its load-bearing capacity at a temperature of 450 to 650°C, causing large deformations and causing steel columns and beams to bend. As a result, they cannot be used due to excessive deformation.

Usually unprotected steel structures are fire-resistant. The limit is approximately 15 minutes. The length of this period of time is also related to the speed at which the component absorbs heat.

In order to overcome the fire protection defects of steel structure materials in practical applications, fire protection treatment must be carried out, the purpose of which is to improve the fire resistance of steel structures to the limit specified in the design code.

Prevent the steel structure from heating up rapidly in a fire and causing deformation and collapse. The measures are varied. The key is to use different methods according to different situations, such as blocking the flame with insulation and refractory materials, and directly burning the steel structure to reduce the heat transfer rate.

Delay the time of heating up and weakening of the steel structure. But no matter what method is used, the principle is the same. Several fire protection measures for different steel structures are introduced below.

The first is the outer layer. It adds an outer layer to the outer surface of the steel structure, which can be cast or sprayed on site. The cast-in-place solid concrete cladding is usually reinforced with steel mesh or steel bars to limit shrinkage cracks and ensure the strength of the casing. The spraying method can spray the sand pump on the surface of the steel structure at the construction site to form a protective layer.

The sand pump can be lime cement or gypsum mortar, or it can be mixed with perlite or asbestos. At the same time, the outer coating can also be made of perlite, asbestos, gypsum or asbestos cement, and lightweight concrete, and fixed on the steel structure with adhesives, nails and bolts.

2. Water (water jacket). Water filling is the most effective fire protection in hollow steel structures. This method keeps the steel structure at a low temperature during a fire, and the water circulates in the steel structure to absorb the heat of the material itself. The heated water can be recycled after cooling, or cold water can be introduced from the pipeline to replace the heated water.

3. Shielding. The steel structure is placed in a refractory wall or ceiling, or the component is hidden in the space between the two walls, adding a little refractory material or adding refractory material can achieve the purpose of fire prevention. This is the most economical way to extinguish fires.

4. Expansive materials. The steel structure fireproof coating protection component adopts fireproof and heat insulation performance. The construction is not restricted by the geometric shape of the steel structure. Generally, no auxiliary facilities are required. The coating is light in quality and has a certain beautiful decorative effect. It belongs to modern advanced fire protection technology measures.

At present, there are more and more high-rise steel structures, especially some super high-rise buildings, which are all built with steel materials. Once a fire accident occurs in a high-rise building, the fire will not be extinguished in a short time.

This requires us to strengthen the fire protection of building materials in building design to enhance their fire resistance and develop necessary emergency response in the building. Plan to reduce casualties and property damage.

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