Steel structure of the plant design and construction of 9 key points (I)

The steel structure plant has been widely recognized in construction engineering due to its fast construction speed, light weight, good seismic performance, environmental protection, and other characteristics. It has gradually replaced bulky reinforced concrete in the design of industrial plants.

The application of steel structure plants in China is not long, and their specific design and construction techniques are still in the exploration stage. Although steel structure industrial plant has many advantages, as a material, it also has many disadvantages, such as poor fire resistance, easy to rust and corrosion, etc., which must be taken into account in the process of design and construction.

I.The superiority of the steel structure plant is summarized

The main advantages of steel structure industrial plant are: firstly, in terms of construction speed: steel structure components can be factory mass production, simple construction, fast installation, greatly shortening the construction cycle; secondly, steel structure industrial plant in terms of self-weight: it can reduce the structural mass of the building by about 30%, especially in the places with low bearing capacity of foundations and high seismic intensity, its comprehensive economy is better than that of the reinforced concrete structure system; Finally, in terms of environmental protection: steel structure system belongs to environmentally friendly green building system, steel itself is a kind of high-strength and high-efficiency material with high recycling value, and it does not need to make mold construction.

II.The importance of steel structure plant drawing design

No matter what kind of project, drawings are the basis of construction. During the design of steel structure industrial plant, professional and technical personnel of the construction unit should be organized to review the drawings, check the “mistakes, omissions, bumps and defects” in the construction drawings, and strive to solve the problems before construction, to reduce the influence of the quality and progress of the project due to the problems of the drawings. The steel structure project should prepare a construction organization design for the production stage and installation stage, respectively, and the content of the steel structure production process should include the quality standard and technical requirements of each process and each sub-project in the production stage, as well as the specific measures formulated to ensure the quality of products.

III.Design principles for steel structure plant support system

Too ensure the space work of steel structure plant, improve its overall rigidity, bear and transfer longitudinal horizontal force, prevent excessive deformation of rods, avoid the instability of compression rods, and ensure the overall stability of the structure, a reliable support system should be arranged according to the form of the plant structure, the setup of the workshop crane, vibration equipment, and the span of the plant, the height, and the length of the temperature zone. Each temperature section of the plant should be set up to stabilize the inter-column support system and coordinate with the roof horizontal support arrangement. The location of the lower column support is an important factor in determining the direction of deformation of the longitudinal structure of the plant, and affect the size of the temperature stress, the lower column support should be located in the middle of the temperature zone as far as possible, so that longitudinal components such as crane beams can be more freely with the temperature change to the zone at both ends of the expansion and contraction. When the length of the temperature section is not large, generally in the middle of the temperature section to set a lower section column support, but the length of the temperature section is greater than 150 meters, to ensure the longitudinal rigidity of the plant, should be set in the temperature section of the two lower section column support, and its location should be arranged as far as possible in the middle one-third of the range of the temperature section, to avoid excessive temperature stress, the two center distance between the two supports should not be greater than 72 meters. In order to avoid excessive temperature stress, the center distance between the two supports should not be greater than 72 meters.

IV.Focus on seismic design of steel-framed plants

In the seismic design of steel structure industrial plant, attention should be paid to: firstly, in the overall arrangement, the quality and stiffness of the plant structure should be evenly distributed, so that the force of the plant is uniform, the deformation is coordinated, and the unfavorable effect on the seismic resistance due to the uneven stiffness of the structure is avoided as much as possible, and the transverse structure of the plant should adopt the frame of rigid frame or make the roof frame and the columns have a certain degree of solidity to take full advantage of the force performance of the steel structure and reduce the transverse structure. Secondly, the damage of steel structure plant is generally not due to insufficient strength of rods but often caused by the instability of rods, so it is especially important for steel structure plant to reasonably arrange the support system to ensure the overall stability of the plant structure; lastly, there exists a low circumference fatigue under the seismic effect, and attention should be paid to the effect on the plant when designing. The design of structural joints should ensure that the destruction of nodes does not precede the yielding of the full cross-section of structural members, and the structural members should be able to enter the plastic work and fully absorb the seismic energy to play their seismic capacity.

V.Importance of heat-resistant design for steel structure plants

Steel structure industrial plant fire prevention ability is very poor, when the steel is heated above 100 ℃, as the temperature rises, the tensile strength of the steel reduces, plasticity increases; temperature in 250 ℃ or so, the tensile strength of the steel is slightly increased, while the plasticity is lowered, blue brittle phenomenon; when the temperature is more than 250 ℃, the steel appears to be the phenomenon of creeping; when the temperature reaches 500 ℃, the strength of the steel drops to a very low level, so that steel structure Collapse. Therefore, when the surface temperature of a steel structure is above 150℃, heat insulation and fireproof design must be done (usually, heat-resistant coating is applied to solve the problem).

And the problems in the construction of a steel structure industrial plant are very tedious; here we only analyze and study the more prominent ones.