Rebar Configuration for Prefabricated Houses

The rebar configuration for prefabricated houses should be determined based on specific design requirements, component uses, load conditions, and national standards. Common configurations are as follows:

1. Prefabricated Hollow Slabs

• Main Tension Rebars: Located in the tension zone at the bottom of the slab, typically configured with 4-8 hot-rolled rebars (such as HPB300 or HRB400), with diameters ranging from 6-12mm. For example, a hollow slab that is 1200mm wide and spans 4m may use 6 main rebars with a diameter of 8mm.
• Distribution Rebars: Used to resist temperature and shrinkage stresses, with diameters of 6-8mm and spacing of 150-300mm, arranged along the width of the slab.
• Prestressed Rebars: If prestressing technology is used, 2-4 high-strength steel strands (with diameters of 9.5-15.2mm) may be employed, partially or fully replacing the main tension rebars to enhance crack resistance.

2. Prefabricated Solid Slabs

• Bidirectional Tension Rebars: Tension rebars are arranged in both the longitudinal and transverse directions of the slab, typically at a density of 6-10 rebars per meter, with diameters of 8-12mm, to withstand bidirectional loads.
• Structural Rebars: With diameters of 6-8mm and spacing of 200-300mm, used to control crack widths and improve durability.
• Additional Rebars: In areas of concentrated stress (such as supports), 2-4 additional rebars may be added to enhance local load-bearing capacity.

3. Special-Purpose Prefabricated Slabs

• Bridge Deck Slabs, Wall Panels, etc.: The number of rebars significantly increases. For example, bridge prefabricated slabs may be configured with 10-20 main rebars (with diameters of 10-16mm), supplemented by dense distribution rebars and shear rebars (such as stirrups) to cope with complex load conditions.
• Shear Design: In areas with high shear forces (such as beam-column joints), stirrups or bent-up rebars need to be added, with spacing and diameters determined through calculation.

4. Prefabricated Slabs for Houses with a Clear Span of 5.2m × 4.2m

• Main Rebars: It is recommended to use HRB400-grade deformed steel bars, with diameters of 10-12mm and spacing of 100-150mm, to meet the load-bearing requirements of the large span.
• Distribution Rebars: Options include 8-10mm rebars with spacing of 150-200mm, tied with the main rebars to form a rebar mesh.
• Edge Reinforcement: Radiating rebars or additional negative moment rebars need to be added at the corners of the slab to prevent cracking due to stress concentration.

5. Reference for Rebar Usage

• Usage per Square Meter: Typically ranges from 5-12 kg, depending on the slab thickness (an 8cm-thick slab requires approximately 5-7 kg/m², while a slab thicker than 12cm requires 10-12 kg/m²) and load requirements (industrial plants require an increase of 30%-50% in usage).
• Rebar Ratio Control: Must meet the requirements of the "Code for Design of Concrete Structures" (GB 50010-2010) to avoid insufficient or excessive rebar ratios.

Design Basis: All configurations must adhere to national standards and industry norms, ensuring that parameters such as rebar ratio, rebar diameter, and spacing meet requirements and are verified for safety through structural calculations.