How is the steel structure of prefabricated warehouse designed?

The steel structure design of a prefabricated warehouse needs to consider many aspects. The following are detailed design steps and key points:

1. Preparation before design

Clear design requirements

• Determine the purpose of the warehouse, such as the type of goods stored, weight, loading method, etc., which will affect the bearing capacity requirements of the structure.
• Understand the use environment of the warehouse, including climatic conditions (wind load, snow load, temperature change, etc.), earthquake fortification intensity, etc., to determine the corresponding load values.
• Determine the size requirements of the warehouse, including length, width, height, etc., as well as structural parameters such as column spacing and span.
• Consider other special requirements such as building appearance requirements, fire protection requirements, and anti-corrosion requirements.

Collect information

• Consult relevant specifications and standards, such as “Steel Structure Design Standard” (GB 50017), “Building Structure Load Code” (GB 50009), etc.
• Collect the geological survey report of the site to understand the nature of the foundation soil and provide a basis for foundation design.
• If there are similar built projects, you can refer to their design experience.

2. Structural selection

Structural system selection

• Gate frame structure: suitable for warehouses with large spans and low heights, with the advantages of simple structure, convenient construction and low cost. The portal frame can be single-span or multi-span, and the roof is generally a sloped roof.
• Truss structure: For large-span warehouses, truss structure is a common choice. The truss can be a plane truss or a space truss, connected to the column through a support system. The advantages of the truss structure are high bearing capacity and high rigidity, but the construction is relatively complex.
• Grid structure: suitable for warehouses with ultra-large spans, with good spatial force performance, high rigidity and high stability. The grid structure can be connected by bolt ball nodes or welded ball nodes.

Roof and wall system selection

• Roof system: corrugated steel plate roof, sandwich panel roof, etc. can be used. The corrugated steel plate roof has the advantages of light weight, convenient construction and low cost, but the thermal insulation performance is relatively poor. The sandwich panel roof has good thermal insulation performance, but the cost is high.
• Wall system: corrugated steel plate wall, sandwich panel wall, etc. can be used. The selection of wall system should take into account aesthetics, thermal insulation, fire protection and other requirements.

3. Load calculation

Permanent load

• Structural self-weight: Calculate the self-weight of the structure according to the material specifications and dimensions of the steel structure.
• Roof dead load: Includes the weight of roof materials (such as corrugated steel plates, sandwich panels, etc.), insulation layer, waterproof layer, etc.
• Wall dead load: Includes the weight of wall materials (such as corrugated steel plates, sandwich panels, etc.).

Variable load

• Roof live load: Determine the value of roof live load according to the use of the warehouse, generally 0.5kN/m²~1.0kN/m².
• Wall live load: Generally 0.5kN/m².
• Wind load: Calculate the wind load according to the basic wind pressure, ground roughness, building height and other factors of the warehouse location. The calculation of wind load should consider wind vibration coefficient, body shape coefficient, etc.
• Snow load: Calculate the snow load based on the basic snow pressure and roof slope of the warehouse location. The calculation of snow load should take into account the snow distribution coefficient, etc.
• Crane load: If there is a crane in the warehouse, the crane load should be calculated based on the crane’s lifting weight, span, working level and other factors. The crane load includes the crane’s vertical load and lateral horizontal load.

Earthquake action

Determine the calculation method and earthquake influence coefficient of the earthquake action based on the earthquake fortification intensity and site category of the warehouse location. The calculation of earthquake action should consider factors such as the natural vibration period and vibration mode of the structure.

4. Structural analysis

Static analysis

Use structural analysis software (such as PKPM, SAP2000, Midas, etc.) to perform static analysis on the steel structure and calculate the internal force (axial force, bending moment, shear force, etc.) and deformation (displacement, deflection, etc.) of the structure under various loads. According to the calculation results, the strength, stiffness and stability of the structural components are checked to ensure that the structure meets the design requirements.

Dynamic analysis

If there are cranes or other vibrating equipment in the warehouse, dynamic analysis should be carried out to calculate the response of the structure under dynamic loads. Dynamic analysis can be carried out using methods such as time history analysis or response spectrum analysis.

5. Component design

Steel column design

• Determine the cross-sectional form and size of the steel column based on the calculated axial force, bending moment and shear force. Steel columns generally use cross-sectional forms such as H-shaped steel and box-shaped columns.
• Check the strength, stiffness and stability of the steel column, including axial compression stability, eccentric compression stability, local stability, etc.
• Determine the connection method between the steel column and the foundation, generally using anchor bolt connection or embedded anchor bolt connection.

Steel beam design

• Determine the cross-sectional form and size of the steel beam based on the calculated bending moment and shear force. Steel beams generally use cross-sectional forms such as H-shaped steel and I-shaped steel.
• Check the strength, stiffness and stability of the steel beam, including normal stress strength, shear stress strength, local stability, etc.
• Determine the connection method between the steel beam and the steel column, generally using welding connection or high-strength bolt connection.

Roof and wall support design

• The function of the roof and wall support system is to ensure the overall stability of the structure and transfer horizontal loads.
• According to the layout and load conditions of the structure, determine the form and layout of the support system. Generally, horizontal roof support, column support, roof corner support, etc. are adopted.
• Design the components of the support system, including the cross-sectional form and size of the support, connection method, etc.

Node design

• Node design is an important part of steel structure design. The reliability of the node directly affects the overall performance of the structure.
• According to the connection method of the components, design the nodes, including welding nodes, high-strength bolt connection nodes, etc.
• Node design should meet the requirements of strength, stiffness and stability, and the feasibility and convenience of construction should be considered.

6. Foundation design

Determine the foundation form

According to the structural form, load size, geological conditions and other factors of the warehouse, determine the form of the foundation. Generally, independent foundation, strip foundation, pile foundation, etc. are adopted.

Calculate the foundation load

Transfer the load (including column bottom axial force, bending moment and shear force) transmitted from the upper structure to the foundation, and calculate the foundation load.

Conduct foundation design

• Based on the foundation load and geological conditions, conduct foundation design, including determining the foundation size, burial depth, reinforcement, etc.
• Conduct foundation verification, including foundation bearing capacity verification, foundation settlement verification, etc.

7. Construction drawing design

Draw drawings

• Based on the design results, draw the construction drawings of the steel structure, including structural layout drawings, component details, node details, foundation details, etc.
• Construction drawings should be clear and accurate, with complete dimension markings to facilitate construction.

Prepare design instructions

• Prepare steel structure design instructions, including design basis, design conditions, material selection, construction requirements, etc.
• The design instructions should be detailed and clear to provide guidance for construction.

8. Construction and acceptance

• During the construction process, construction should be carried out strictly in accordance with the construction drawings and relevant specifications to ensure construction quality. The installation of steel structures should adopt appropriate construction methods and processes to ensure the accuracy and stability of the structure.
• After the construction is completed, acceptance should be carried out, including inspections of the structure’s size, deformation, weld quality, anti-corrosion coating, etc., to ensure that the structure meets the design requirements.

In short, the steel structure design of prefabricated warehouse need to take into account multiple factors, and ensure the safety, reliability, economy and beauty of the structure through reasonable structural selection, load calculation, structural analysis, component design and foundation design. At the same time, the quality should be strictly controlled during the construction process to ensure that the quality and performance of the structure meet the design requirements.