The steel structure has the advantages of light building weight, a small cross-section of components, a high degree of mechanized construction, and less on-site installation work. Structures assembled under the condition of the cross-section are mostly used as large-span structures such as heavy industrial workshops, warehouses, garages, and high-rise and super-high-rise structures.
There are strict requirements for the purchase of raw materials, lofting and cutting, edge processing, assembly and welding, correction, heat treatment, painting, forming, fire prevention, etc. of steel structures. Steel structures are mostly used for multi-layer and high-rise structures. In order to improve the construction quality, it is necessary to control every process that affects the quality of the steel structure, especially the painting and fire prevention measures after the production is completed.
Steel structure buildings must take fire protection measures so that the buildings have a sufficient fire-resistance rating. Prevent the steel structure from rapidly heating up to the critical temperature in the fire, prevent excessive deformation and even the collapse of the building, thereby winning precious time for firefighting and safe evacuation of personnel, and avoiding or reducing the loss caused by the fire.
Fireproofing Methods for Steel Structures
Fire protection measures for steel structures can be divided into two methods:
The first method is to coat, coat, and wrap fireproof materials on the surface of the steel structure to prevent or block the diffusion and spread of heat to the base material, and to extend the fire resistance limit of the steel structure;
The first type of fire protection measures for steel structures mainly include the following:
- Apply fire retardant paint.
Coating fire retardant coating: Fire retardant coating for steel structure refers to a kind of fireproof material that can form a fire-resistant and heat-insulating protective layer after being coated on the surface of steel structure and provide the fire-resistant performance of steel structure. It is light in weight and simple in construction and is suitable for components of any shape and position. It has mature technology and is the most widely used, but it has strict requirements on the coated substrate and environmental conditions.
2. Fireproof board covering.
Fireproof board cladding: Fireproof board protection does not have high requirements on environmental conditions and steel base surface, good decorative effect, anti-collision, impact wear resistance, construction is not restricted by environmental conditions, high construction efficiency, especially suitable for cross-operation and non-permissible For wet construction.
3. Outsourcing concrete.
Outsourcing concrete masonry: Concrete can be general concrete or aerated concrete. The protective layer has high strength, and impact resistance, and occupies a large space. It is difficult to construct on steel beams and diagonal braces. It is suitable for easy collision, with no Fire protection from steel columns for cladding panels.
4. Covered with flexible felt insulation material.
Flexible felt-like thermal insulation material coating: good thermal insulation, easy construction, low cost, suitable for indoor parts that are not easily damaged by mechanical damage, and protected from water.
5. Composite fire protection.
Composite fire protection: Composite fire protection includes two methods of covering fireproof paint with fireproof board or felt insulation material. When composite fire protection is used, it should be ensured that the construction of the outer cladding does not cause structural damage or damage to the inner fire protection layer.
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The second method is to pour materials such as liquid or mixed soil inside the steel pipe to absorb heat from the steel substrate in time so that the temperature of the steel rises slowly and prolongs the time for the steel to heat up to the critical temperature.
The second fire protection measure for steel structures:
Concrete-filled steel tube member: refers to a member formed by filling a circular or rectangular steel tube with concrete, and the steel tube and concrete are jointly stressed in the whole project under load. In the event of fire, the core concrete of the steel pipe has the function of absorbing the heat on the surface of the steel pipe.
Adopt an automatic sprinkler system: automatic sprinklers can not only put out the fire, but also reduce the temperature of the fire field, cool the steel structure, and the cost is low. When the automatic sprinkler system protects the steel roof truss load-bearing members, the sprinklers should be arranged along the direction of the roof load-bearing members and above the steel structure. The spacing between the sprinklers should be about 2.2m. The system can be set independently or combined with the automatic fire extinguishing system.
Steel structure fireproof coating construction
Construction of thin-coated steel structure fireproof coating
1. When the surface of the steel substrate is rust-removed and anti-rust treatment meets the requirements, and the dust and other sundries are removed, the construction can be carried out.
2. The bottom layer is generally sprayed. The thickness of each spray should not exceed the thickness of the previous one. It must be sprayed again after the previous one is dried.
3. When spraying, ensure that the coating is completely closed and the outline is clear
4. The operator should carry a thickness gauge to detect the thickness of the coating and ensure that the spraying reaches the thickness specified in the design
5. When the design requires the coating surface to be smooth and smooth, the last coating should be troweled to ensure that the outer surface is even and smooth.
Construction of fire retardant coating for thick-coated steel structure
The thick-coating steel structure’s fireproof coating should be sprayed by a pressure-feeding sprayer. The air pressure should be 1. The diameter of the spray gun should be the same as that of the ingredients.
The spraying construction should be completed in stages. The thickness of each spraying should be done after the previous one is basically dried or cured. The spraying protection method should be determined according to the construction design requirements.
During the construction process, the operator should use a thickness gauge to detect the thickness of the coating and stop spraying until it meets the thickness specified in the design.
After spray coating, mastoids should be removed to ensure evenness