With the rapid development of national economy, steel structure plays a pivotal role in the field of construction, playing a more and more important role, no matter in industrial or civil buildings, steel structure with its outstanding characteristics is rapidly occupying a wider and wider market.
Its characteristics are: the overall stiffness and seismic performance is good, fast construction speed, light weight, high bearing capacity, in the large span and super-tall building instead of the reinforced concrete structure, but also there is a fire such as poor performance, easy to corrosion defects, according to the characteristics of the foster strengths and circumvent weaknesses in the design to better play to the role of the steel structure, now the present situation of steel structure workshop design and optimization measures for analysis.
1. Overview of steel structure industrial plant
1.1, the superiority of steel structure industrial plant
At present, in the process of engineering plant design and construction in our country, people mainly use steel structure materials as its main construction materials. Its advantages are mainly reflected in the following aspects:
(1) in the process of site construction of industrial plants, because the steel structure materials can be industrialized mass production, and the mechanical equipment used in the process of construction can be assembled on site.
Therefore, this greatly shortens the construction period of the project and reduces the total project investment cost.
(2) Comparing steel structure material with concrete structure material, steel structure material has the characteristics of light weight and high strength. Therefore, in the process of practical application, it can not only greatly reduce the load generated in the use of the building structure, but also effectively improve the stability and reliability of the plant structure.
And in the use of reliable anti-corrosion measures after the steel structure also has a strong corrosion resistance, which also makes the industrial plant structure in use will not be affected by external environmental factors, so that the stability and durability of the structure of the problem.
(3) Steel structure materials in the use of the process of strength is relatively high, the investment cost is relatively low, but also can be recycled for many times, which makes the steel structure industrial plant has a good environmental protection and energy saving function, for the sustainable development of China's social economy has laid a solid foundation.
1.2. Design principles of steel structure industrial plant
Steel structure design of industrial building we should departure from the engineering actual situation, when the reasonable material selection, structure scheme and structural measures to meet the structures in the process of transportation, installation and use of strength, stability and stiffness requirements, accord with the requirement of fire prevention, anti-corrosion, and should be preferred by gm and standardization of components, reduce the production, installation work.
In the steel structure design document, the design service life of the building structure, the grade of steel used, and the type (or steel number) of the connecting materials shall be indicated.
2, the main characteristics of the structural design of steel structure industrial plant
Steel structure plant is widely used all over the world, especially in the developed countries.
The steel structure factory building is usually suitable for warehouse, industrial workshop, guildhall, exhibition hall, purification workshop and supermarket. The main features of the design are as follows:
(1) with a large space and span, and the building quality is light, high strength;
(2) The design generally chooses the most advanced method, which can fully meet the steel impact resistance, deformation ability, shock resistance and rigidity and other requirements;
(3) steel structure building can be used repeatedly, and moving is very convenient, avoid a lot of steel waste, protect the environment from pollution;
(4) The steel structure is unique and light, the actual occupation area is small, the application area is wide, and the use space in the building is increased;
The components are standard, well-made, convenient and fast installation, effectively shortening the construction period and reducing the investment cost;
In the adoption of reliable fire and corrosion prevention measures with higher fire resistance and strong corrosion resistance.
3, steel structure industrial plant design status and optimization countermeasures
The coupling effect of axial force and bending moment, and the relationship between global stability and local stability are the key issues in the study of the stability of steel structure plant.
At present, the safety factor in the design of steel structure plant can not reflect the correlation between the whole and the part.
The structural parameters are uncertain, the structural responses differ significantly, and the extreme value of the random parameter structure is in the unstable state.
Therefore, it is necessary to continuously optimize the design of steel structure plant, improve its performance and safety performance.
3.1. Optimize the heat insulation and fire protection of steel
Steel has a very high thermal conductivity, the thermal conductivity of 50 W (m.℃), when the heat reaches more than 100 ℃, the tensile strength will be reduced, plasticity increases;
When the temperature reaches 250 ℃, the tensile strength of the steel will increase slightly, but the plasticity will decrease, and the phenomenon of blue embrittlement will appear.
When the temperature reaches 500 ℃, the steel strength drops to a very low level, which will cause the steel structure to collapse.
Therefore, when the environmental temperature of the steel structure reaches more than 150 ℃, it is necessary to do the design of heat insulation and fire prevention.
Its approach is commonly: steel structure outside package firebrick, concrete or hard fireproof plate.
Or steel structure brush thick coating type fire retardant coating, thickness according to the "steel structure fire retardant coating technical regulations" calculation.
3.2. Optimize the facade design of steel structure industrial plant
The construction of light steel structure is mainly characterized by the following four aspects: scale, line, color and change.
The facade of the steel structure industrial plant is mainly decided by the process layout. Under the requirement of meeting the process, the facade is simple and grand, and the node is as simple and unified as possible.
Color moulded steel plate makes the light steel factory building appear light and colorful, which is obviously better than the heavy and single traditional reinforced concrete structure.
In the design of light steel factory buildings, jumping colors and cool colors are often used to highlight the main entrance, outer gutter, edge flooding and other places, which not only reflects the magnificent manner of modern factory buildings, but also enriches the facade effect.
Traditional reinforced concrete structure industrial factory building, external wall maintenance for brick masonry, exterior decoration for paint or brick, supplemented by ribbon, because the concrete roof setting lighting window effect is not ideal, usually set a large number of lighting window in the wall design.
But for the maintenance of the wall for color profiled steel plant is not the case.
Lines are the most unique feature of the architectural style of light steel structure. Uniform lines, either horizontal or vertical, make light steel structure buildings with smooth metallic texture, reflecting a strong modern industrial atmosphere.
3.3. Optimize the support system of steel structure industrial plant
In the process of the arrangement of the support system between columns and roof in the steel structure industrial plant, the actual vibration equipment, tonnage, span, structure form, column network setting, height and crane setting should be decided.
In general, purlins, irrespective of roof structure, are primarily set on vertical bracing.
In a purlin - free system, the roof panels are welded to the roof truss for winding support.
However, in the actual design process, due to the constraints of construction conditions.
Taking into account the installation requirements, the upper chord transverse support system should be set in the upper chord position of the roof truss and the upper chord position of the skylight frame.
At the same time, when the space between the workshop and the roof truss is more than 12m, or when there is a heavy vibration equipment and a bridge crane, the vertical horizontal support system should be set.
3.4. Optimize the roof design of steel structure industrial plant
In the roof design of steel structure workshop, the main content is waterproofing.
Roof waterproof design mainly consider three aspects of the factors: one is the roof slope;
The second is the gutter form;
The third is the length of single slope roof.
Implement related roof engineering technical standards. In actual projects, the roof slope of many workshops is between (2%~3%), which meets the actual requirements.
Taking into account material properties, node handling and technology, the slope should be set at 5%.
In the area with snow cover, the slope should increase, and the design of single-slope roof length of steel structure workshop should pay attention to the temperature difference and rainfall change in the area.
According to the relevant engineering design data, the length of the single-slope roof should be controlled below 70m in order to ensure the performance of the plant.
When this standard value is exceeded, special treatment is required.
The current application of more common steel structure roof design scheme mainly has two kinds: the first, the use of double-layer color pressed steel plate, its insulation cotton helps waterproof, but the temperature change is large, it is difficult to solve the problem of thermal expansion and cold contraction;
Second, the use of composite flexible steel roof system composed of insulation layer, steam insulation layer, waterproof layer and other composite flexible steel roof system, the spread of flexible rolling material, help to improve thermal expansion and cold contraction.
3.5. Anti-rust treatment
The surface of steel structure engineering will rust when it is directly exposed to the atmosphere. When there are corrosive media in the air of the steel structure plant or the steel structure is in a humid environment, the corrosion of the steel structure plant will be more obvious and serious.
The corrosion of steel structure will not only reduce the section of steel members, but also produce rust pits on the surface of steel members. When the members are stressed, the stress concentration phenomenon will be caused and the structure will be damaged prematurely.
Therefore, enough attention should be paid to the corrosion prevention problem of steel structure factory building components, and corresponding countermeasures and measures should be taken in general layout, technological layout, material selection and other aspects according to the erosion medium situation and environmental conditions of the factory building to ensure the safety of the structure of the factory building.
General steel structure anticorrosive primers and topcoats are often used, coating layer number and thickness are often determined according to the use of the environment and coating properties.
General indoor steel structure under the action of natural atmospheric medium, the coating thickness is required to be 100 μm, that is, two coats of primer and two coats of finish.
Thus, in the process of steel structure industrial plant design, we should not only the steel structure plant strength, stability, seismic performance, durability and other aspects of the performance of strict requirements, but also pay attention to take reliable fire prevention and corrosion prevention measures, so as to effectively improve the stability and reliability of the industrial plant structure
Contact Person: Mr. steven