Steel structure factory: the "steel backbone" of industrial buildings, an evolutionary benchmark from strength to efficiency

Steel structure workshops, industrial buildings with steel as the core load-bearing skeleton, have long become the mainstream choice of modern industry with their characteristics of "strong, light, fast and flexible". From roaring heavy machinery factories to precision electronic workshops, from towering storage workshops to modular temporary production bases, it reshapes the form and efficiency of industrial space with the rigidity of steel and the flexibility of design.
1. "Steel skeleton" of steel structure workshops: core composition and material code
The soul of steel structure workshops lies in the "steel instead of concrete" load-bearing system. Its composition is like the bones and texture of the human body. Every detail is related to safety and efficiency.
1. Core components: the "steel skeleton" that supports the industrial space
Main load-bearing structure:
Steel columns: the "vertical pillars" of the factory building, mostly H-shaped steel (with an "H"-shaped cross section and strong bending resistance) or box columns (closed cross section, excellent compression and torsion resistance, suitable for heavy-duty factories), with heights ranging from 5 meters (single-story light factory building) to 30 meters (multi-story heavy-duty workshops), and the bottom is rigidly connected to the concrete foundation through anchor bolts to transfer the load to the ground.
Steel beams: The "horizontal ridge beams" connecting the steel columns are also mainly H-shaped steel. According to the force, they are divided into main beams (bearing roof and crane loads, with a span of more than 30 meters) and secondary beams (connecting the main beams and sharing local loads), which are fixed to the steel columns through welding or high-strength bolts to form a stable "portal frame" or "rack" system.
Roof and wall system: non-load-bearing "enclosure structure", the roof is made of corrugated steel sheet (thickness 0.3-0.8mm, surface galvanized or color-coated, rust-proof and lightweight), with insulation wool (glass wool or rock wool, thermal conductivity ≤0.04W/(m・K)) and purlins (C-shaped steel or Z-shaped steel, supporting the weight of the roof); the wall is also made of corrugated steel sheet, and some factories have light strips with tempered glass for lighting needs.
Special functional components:
Crane beam: the "core equipment" of heavy factories, used to install bridge or gantry cranes (lifting capacity from 5 tons to 500 tons), mostly welded I-shaped sections, need to withstand the vertical load and horizontal impact force when the crane is running, and its deflection is strictly controlled (the maximum deflection does not exceed 1/400 of the span) to avoid affecting the accuracy of the crane.
Support system: The "invisible stabilizer" of the factory building, including roof support (horizontally, resisting the horizontal force caused by wind load) and column support (vertically, enhancing the overall lateral stiffness, especially in earthquake or strong wind areas), made of angle steel or round steel, looks slender but can make the factory building "unmoved" under strong load.
2. Material properties: Why is steel the preferred choice for industrial buildings?
The advantages of steel structure factories are rooted in the "mechanical talent" of steel itself:

The golden ratio of strength and self-weight: The tensile and compressive strength of steel can reach more than 345MPa (about 10 times that of concrete), but the self-weight is only 1/3-1/5 of that of concrete structure (such as a steel beam with a span of 20 meters, the weight per square meter is about 50kg, while the concrete beam with the same span needs more than 200kg), which greatly reduces the foundation bearing pressure, especially suitable for soft soil foundation.
Plasticity and toughness: Steel will not break suddenly after the force exceeds the yield point, but will undergo recoverable plastic deformation (such as absorbing energy through slight deformation during an earthquake). Its impact resistance is far superior to that of brittle concrete, which is also the core reason why steel structures are preferred in earthquake-prone areas.
Industrialization attributes: Steel components (steel columns, steel beams, purlins) can be accurately prefabricated in the factory (cutting, welding, drilling errors are controlled within ±2mm), and only bolts or welding splicing are required on site to avoid the long cycle of concrete "formwork, pouring, and maintenance", which is the key to its construction efficiency.
2. "Design wisdom" of steel structure workshops: precise balance from safety to adaptation
The design of steel structure workshops is not a simple "steel component splicing", but requires a balance of the three core elements of load, environment, and function, so that the steel skeleton can be both "bearable" and "well used".
1. Load calculation: let each steel "have a certain amount of force"
The first step in plant design is to clarify "what force it bears", and then match the steel component specifications accordingly:

Constant load: the weight of the plant itself (steel, roof and wall materials, fixed weight of equipment), such as a 1000㎡ light plant with a constant load of about 50-80kN (equivalent to 5-8 tons).
Live load: variable load, including crane load (including vertical lifting weight and horizontal braking force), roof live load (snow load is determined by region, such as 0.7kN/㎡ in the north), temporary load of personnel and equipment (generally 0.5kN/㎡).
Special load: wind load (typhoons need to be considered in coastal areas, wind pressure can reach more than 0.6kN/㎡, which may cause lateral deformation of the plant), earthquake load (calculated according to the building seismic fortification intensity, high intensity areas need to enhance node rigidity).
For example: A heavy-duty factory building with a 30-ton crane needs to use high-strength low-alloy steel (Q355B) for its crane beam, with a cross-sectional height of more than 1.2 meters to withstand repeated impacts during crane operation.
2. Node processing: The "joints" of steel structures must be "unbreakable"
The connection nodes of steel components are the "top priority" of design, just like human joints, which determine the overall stability:

Rigid connection nodes: used for parts that need to transmit bending moments (such as the connection between steel columns and main beams), fixed by full penetration welds (weld thickness ≥ 1/2 of the steel thickness) or high-strength bolts (8.8 or 10.9, preload force up to 200-300kN), to ensure that the nodes "do not rotate or move".

Hinged nodes: used for parts that mainly transmit shear forces (such as the connection between secondary beams and main beams), connected by bolts or pins, allowing slight rotation (such as the connection between roof purlins and steel beams) to avoid stress concentration.
Anti-corrosion and fire prevention: Steel is "afraid of rust and fire", so targeted protection is required:
Anti-corrosion: After rust removal, apply primer (epoxy zinc-rich paint, thickness ≥60μm) + intermediate paint (micaceous iron paint) + topcoat (fluorocarbon paint or acrylic paint, total thickness ≥120μm), which can ensure 15-20 years of no rust; the thickness of the zinc layer needs to be increased in humid areas or chemical workshops (such as hot-dip galvanizing, zinc layer thickness ≥85μm).
Fire prevention: According to the fire resistance level of the factory building (such as the fire resistance limit of 1.5 hours for Class D factory building columns), apply fire retardant coating (thin coating type is used for light load components, thick coating type is used for steel columns and main beams, with thickness ranging from 5-25mm). When encountering fire, the coating expands to form an insulation layer to delay the temperature rise of the steel (steel will lose its bearing capacity when it exceeds 600℃).
3. Functional adaptation: Make the factory "customized on demand"
Factory buildings in different industries have special requirements for steel structures, and the design needs to be "tailored":

Heavy industrial factory buildings (such as machinery factories and metallurgical workshops): need to adapt to large cranes (more than 50 tons), so the steel columns need to use box columns (torsion resistance), the crane beams use welded I-shaped sections and are equipped with brake plates (to enhance lateral stiffness), the span is mostly 18-30 meters, the column spacing is 6-12 meters, and the ground needs to be poured with 300mm thick concrete and reinforced (to bear the weight of the equipment).
Light industrial factory buildings (such as electronics factories and food workshops): small loads (no large cranes), portal frame structures can be used (steel columns and steel beams are rigidly connected to form a "door" shape, with a span of 20-40 meters and a column spacing of 8-15 meters), the roof can be designed as a slope roof (drainage) or a flat roof (convenient for installing photovoltaic panels), and the wall can use color steel plates + insulation layers (to meet constant temperature requirements).
Warehousing and logistics plant: pursuing "large space and high utilization", mostly adopting column-free large span design (span 30-60 meters), light purlins + corrugated steel plates for the roof, hardened ground (wear-resistant floor), and reserved forklift channels (width 3-4 meters) and loading and unloading platform interfaces.
3. "Application scenarios" of steel structure plant: comprehensive penetration from traditional industries to emerging fields
With the characteristics of "adjustable strength, flexible span, and fast construction", steel structure plant has become the "preferred architectural form" in many industries and has shown unique advantages in emerging fields.

Heavy industry (machinery, metallurgy): The core requirements of this type of scene for the plant are load resistance, impact resistance, and adaptability to large cranes. Therefore, in the design of steel structure, box-type steel columns will be used with heavy crane beams, and the nodes will be rigidly connected to ensure stability. At the same time, the fire protection level must reach level 1 to ensure safe operation under high temperature and heavy load environments.
Light industry (electronics, food): more attention is paid to the cleanliness and constant temperature performance of the factory, and the load is small. Most of them adopt portal frame structure, and the wall uses color steel plate plus insulation layer to meet the constant temperature requirements. The ground will be cleaned to avoid dust pollution. The span is usually 20-40 meters, and the column distance is 8-15 meters, taking into account the space utilization rate and production environment requirements.
Warehousing and logistics: The core demand is large space and high utilization rate. Therefore, steel structure factories mostly adopt column-free large span design, with a span of 30-60 meters. The roof uses light purlins and corrugated steel plates to reduce the deadweight. The ground is hardened to form a wear-resistant floor. At the same time, a forklift channel and loading and unloading platform interface with a width of 3-4 meters are reserved to facilitate cargo transportation.
New energy (photovoltaic, energy storage): The factory needs to be able to integrate photovoltaic panels, and the construction period is short to meet the needs of rapid production. Flat roof structures are mostly used in design to ensure that the roof load is ≥0.5kN/㎡ to adapt to photovoltaic modules. At the same time, the characteristics of fast steel structure construction are used to shorten the construction period and realize the release of production capacity as soon as possible.
Temporary/modular factory buildings: Emphasis on detachable, reusable and short-term production capabilities. Steel structure components are mainly bolted to achieve standardized production, convenient transportation and reorganization, can be quickly built and put into use, and play an important role in emergency production or short-term projects.
4. "Modern Evolution" of Steel Structure Factory Buildings: Technology Empowerment and Green Transformation
With the upgrading of industry and the improvement of environmental protection requirements, steel structure factories are transforming from "traditional buildings" to "smart green buildings".
1. Intelligent construction: from "on-site welding" to "digital twin"
BIM technology application: Use BIM models to simulate steel component assembly and construction processes in the design stage, discover collision problems in advance (such as conflicts between pipes and steel beams), and reduce on-site rework; during construction, use BIM+GPS positioning to ensure that the verticality error of steel column installation is ≤1/1000 (such as the deviation of a 10-meter-high steel column does not exceed 10mm).
Prefabricated construction: More than 90% of the components are prefabricated in the factory, connected on-site with high-strength bolts (efficiency is 3 times that of welding), and with crane robots (precise lifting error ±5mm), the time from component delivery to capping of a 1,000㎡ factory building can be shortened to 15-30 days (concrete factories take 3-6 months).
2. Green and sustainable: make steel plants "more environmentally friendly"
Recycling: After the steel structure plant is dismantled, the steel recovery rate reaches more than 90% (can be re-melted and processed), which is much higher than concrete (recycling rate is less than 30%), in line with the "carbon neutrality" trend.
Energy-saving transformation: photovoltaic panels can be installed on the roof (the annual power generation of a 1,000㎡ plant is about 120,000 degrees), the wall uses sandwich color steel plates (insulation coefficient ≤ 0.3W/(m・K), reducing air conditioning energy consumption), and the ventilation system is linked with smart sensors (start and stop on demand).
Ecological adaptation: In high-intensity earthquake areas (such as Sichuan and Yunnan), the toughness of steel structures can reduce earthquake damage; in soft soil foundation areas (such as coastal tidal flats), its light weight can reduce the cost of foundation treatment (no deep piles are required).
5. "Maintenance and life" of steel structure workshops: Make the steel skeleton "lasting and new"
Although steel structure workshops are strong, they need regular maintenance to extend their life (the design life is usually 50 years, and it can reach more than 70 years with proper maintenance):

Anti-corrosion maintenance: Check the coating every 5-10 years (whether it is peeling or rusting), and the rusted parts need to be rusted and repainted (especially corners, nodes and other places where water is easy to accumulate).
Structural inspection: Check the bolts (whether they are loose), welds (whether there are cracks), and crane beams (whether they are deformed) every year, and reinforce them in time if problems are found (such as re-tightening bolts and repairing welds).
Fireproof coating maintenance: Check the coating thickness every 3-5 years, and re-apply it if it is insufficient (especially high-temperature working areas need to be inspected more frequently).