Several problems needing attention in the design of Beijing warehouse rental plant.

The problems that need attention in plant design are not only the concern of steel structure designers, but also the concern of business owners! The design of steel structure workshop is related to the quality and safety of steel structure workshop.

With the development of science and technology and the progress of society, the steel used in the construction market has been greatly developed because of its high bearing capacity, high construction efficiency, strong stiffness and good seismic effect, which has replaced the traditional concrete structure in the structural design of industrial plants. Steel structure plants are generally divided into two categories. The first type is heavy-duty steel structure workshop, including steel rolling workshop, large smelting workshop and other tonnage cranes. The second type is light and heavy machinery. The second type is light steel structure workshop, which generally adopts portal steel frame structure. The wall adopts composite plate material, which is widely used in most civil buildings due to its small weight, fast construction speed and low steel consumption. Because it is a kind of material, it has some disadvantages, such as easy corrosion, poor heat insulation effect and seismic resistance. Therefore, the following problems must be paid attention to in the design of steel structure plant.

1、 Fire and heat insulation.

When the temperature of the steel structure is 400 ℃, the strength of the steel structure will decrease. Therefore, when the temperature reaches 150 ℃, corresponding fire protection design and thermal insulation design must be carried out to strengthen the thermal conductivity of the steel structure and avoid strong damage to the steel structure due to the influence of high temperature or flame. In addition, a certain amount of concrete or fire-resistant bricks can be poured around the steel structural members, or thick fire-resistant coatings can be used for insulation. The thickness of the insulation layer is designed according to the local environment. Comfort and industrial requirements should also be considered when carrying out fire prevention and thermal insulation.

2、 Temperature expansion joint.

The size of the steel structure workshop has a certain relationship with the temperature difference and stiffness of the columns. The shape of the steel structure will change due to the change of temperature, which will cause great temperature stress to the structure of the plant. Therefore, when designing a large-area steel structure workshop, in order to avoid the influence of excessive temperature force, the delivery room can be divided into several temperature zones. The temperature joint can be designed vertically and horizontally in the plant. The length of the temperature zone is determined by the specifications of the steel structure. The temperature expansion joint can adopt double column mode or single plant mode. If the design of the temperature slot is vertical, the rolling bracket can also be used. If it is horizontal, it can be slid using an elliptical hole.

3、 Rust prevention of steel structure workshop.

If the steel structure surface is exposed to the atmosphere and there is no reinforced protective film, it will rust. If the steel structure plant is always in a humid environment and there are corrosive media in the air, the corrosion of the steel structure plant will be more serious. The corrosion of steel structure not only reduces the thickness of components, but also forms certain rust pits on the surface of components. When the component is stressed, it will cause concentration and premature damage, so it must be paid enough attention. Generally speaking, the antirust measures for steel structures are usually to apply antirust paint on the surface, and the thickness and number of layers depend on the environment and properties. Generally, due to the influence of the atmosphere, the specified thickness of the indoor steel structure is 110mm, that is, the top coat and primer. Under the action of atmosphere, the specified thickness of open-air steel structure is 160mm ~ 200mm or more. The underground part of the steel column base must be wrapped with concrete with strength greater than C20, and the thickness of the protective layer should be greater than 60mm. For plant components with corrosive media, the thickness of steel must be greater than 10mm, and the thickness of weld must be greater than 10mm.

4、 Seismic design.

Attention shall be paid to the following in seismic design:

1. The damage of steel structure workshop is generally not caused by insufficient strength of members, but by loss of stability. Therefore, the support system must be reasonably configured to ensure the overall stability of the plant.

2. In general, the manufacturer's stiffness and mass are evenly distributed and the stress is uniform, so as to avoid the negative impact caused by the uneven structural stiffness. Steel frame or frame can be used for the transverse structure of the plant to make full use of the strong stress advantage of the steel structure and reduce the deformation of the transverse structure.

3. Under the influence of earthquake, pay attention to the influence of low cycle fatigue. In the design of structural connection points, it should be ensured that the node damage is later than the section yield of structural members, so that structural members can enter plastic work, absorb seismic energy well and play its role.

5、 Facade design of steel structure workshop.

Steel structure buildings have four characteristics: color, line, change and scale. When designing the steel structure workshop, we must grasp these four points. When setting the facade of the steel structure plant, the technology determines how to set it first. It is required that the facade should be unified and the nodes should be simple. Color profiled steel plate is not a traditional reinforced concrete model, but is embodied in rich colors and light body. In the design, in order to highlight the special parts such as the inlet and outlet and the outer ditch, jumping colors are often used. It not only shows the magnificent momentum of the plant, but also shows the concrete effect of the facade. The traditional workshop is composed of concrete, and the outer wall brick and outer layer are made of face brick and paint. Since the daylighting window on the concrete roof cannot achieve the expected purpose, the daylighting window is set on the wall. If color profiled steel plate is used, the effect is obviously different. Lines can show the uniqueness of buildings and the modern flavor of steel structure buildings. If many lighting windows are set on the wall, the lines of the wall will be affected. At the same time, the steel structure roof can be equipped with a certain number of lighting panels to make the lighting uniform and ventilation good.

6、 Roof design.

For the design of the roof, the focus is on the drainage design. The drainage design of roof involves many factors such as the form and slope of roof ditch. The design of slope shall be determined according to the actual situation. For example, where there is a large amount of blood, the slope can be increased quantitatively. The main factors affecting the length of single slope roof are rainfall and maximum temperature difference. According to working experience, the length of single slope roof must be controlled within 60m. If it exceeds 60m, some special treatment must be carried out. At present, the Countermeasures for steel structure roof design are as follows:

1. Add insulation cotton into the two-color profiled steel plate to make a suitable rigid roof.

2. The composite roof is composed of color steel plate inner plate, thermal insulation layer, air barrier plate and waterproof layer.

7、 Roof support system problem.

The system is composed of longitudinal support, lateral support and vertical support. When arranging the roof support system, the height, column network, span, structural form and other factors of the plant must be considered. Generally speaking, vertical support is the main one. The large panel in the purlin free system has three points welded to the roof truss to support the upper chord. However, due to the influence of construction conditions and installation requirements, no matter what kind of roof, it is necessary to design the top chord lateral support on the top chord of skylight and roof. If the space between the roof trusses of the plant is more than 13 meters, or there is a large crane in the plant, the longitudinal horizontal support must be designed.

8、 Selection of column grid size of portal frame.

For the configuration of portal frame column network, the first consideration is to meet the use requirements of the plant. The distance between portal frames is generally 7m ~ 10m, regardless of whether there is a crane. It is suggested that the reasonable spacing of portal frames is 9m ~ 10m. The number of components in the project will directly affect the workload and process of installation and processing. Generally speaking, when 10m spacing is adopted for a project, the number of rigid frame, crane beam and other components must be reduced by 35% compared with 7m spacing. Although the section increases, the project cost is reduced and the construction period is shortened. The reasonable span of portal frame is 20m ~ 23m, of which the maximum span is 35m. Second, structural design. Purlins and wall beams are members connected with rigid frames and also members with horizontal and vertical loads. The longitudinal horizontal force of the plant is supported by the support system. The columns in each temperature zone are equipped with a roof horizontal support system with a spacing of about 42m, which makes the spatial structure of the plant more stable.