Model Numbers of Special Bolts for Prefabricated Houses

There is no unified fixed model number for special bolts used in prefabricated houses, but the commonly used specifications and key points for model selection are as follows:

I. Diameter Specification Range

In the connection of prefabricated house components, the selection of bolt diameters should be determined based on the structural load-bearing requirements. The commonly used diameter range is M16 to M24, among which:

• M16 bolts: Suitable for connecting lightweight components or non-load-bearing parts, such as partition wall panels and decorative components. Their load-bearing capacity can meet general fixing requirements.
• M20 to M24 bolts: Used for load-bearing structures or key node connections, such as beam-column joints and connections between floor slabs and walls, which need to withstand significant shear forces or tensile forces.
• Special scenarios: For components with larger sizes or higher loads (such as high-rise prefabricated houses), bolts of M27 or larger may be required, but this should be determined in combination with specific design calculations.

II. Material and Performance Grades

The material of bolts directly affects the connection strength and durability and should be selected based on the importance of the structure:

• High-strength bolts:
  • Performance grades: Commonly used are grades 8.8 and 10.9, conforming to the standard GB/T 1231-2006.
  • Applicable scenarios: Load-bearing structures and parts subjected to dynamic loads (such as earthquake-prone areas and areas with high wind loads), where forces are transferred through friction-type or bearing-type connections.
  • Advantages: High-strength bolts provide connection stiffness through pre-tightening forces, reducing the risk of loosening and being suitable for long-term load-bearing environments.
• Ordinary bolts:
  • Performance grades: Grade 4.8, made of ordinary carbon steel.
  • Applicable scenarios: Non-load-bearing parts (such as equipment fixing and temporary connections) or scenarios with small loads and less stringent deformation requirements.
  • Limitations: Ordinary bolts are prone to loosening and require regular inspection and maintenance. They are not suitable for high-stress or vibration environments.

III. Key Principles for Model Selection

1. Structural calculation priority: Bolt model numbers should be determined through structural mechanics calculations, including parameters such as shear forces, tensile forces, and bending moments, to ensure they meet the design load requirements.
2. Environmental adaptability: In humid or corrosive environments (such as coastal areas), stainless steel bolts or hot-dip galvanized bolts should be selected to prevent connection failure due to rusting.
3. Construction convenience: The length of bolts should reserve sufficient thread engagement length (usually ≥ 1.5 times the diameter) to avoid affecting the connection strength due to insufficient length.

Summary: The selection of bolts for prefabricated houses should comprehensively consider factors such as diameter, material, performance grade, and environmental conditions. It is advisable to refer to design specifications (such as GB/T 1231-2006) and determine specific model numbers through professional calculations to ensure safe and reliable connections.