How to Use Prefabricated Steel Bars in Houses

The use of prefabricated steel bars in houses requires selecting appropriate methods based on the type of component, connection requirements, and construction scenarios. Common application methods and key operating points are as follows:

I. Connection of Prefabricated Components

1. Steel Bar Sleeve Connection
   Suitable for load-bearing connections of vertical components (such as columns and walls). Insert the ends of two steel bars into a specially made sleeve, and achieve connection through mechanical interlocking or thread tightening. Ensure that the sleeve matches the specifications of the steel bars, and conduct pull-out tests after connection to verify strength.
2. Steel Bar Grouted Splice Connection
   Used for connections of horizontal or vertical components. Insert steel bars into reserved holes in prefabricated components, and pour high-strength non-shrink grout. Achieve steel bar anchoring through the hardening of the grout. Control the hole diameter (usually 2-3 times the diameter of the steel bar) and the fluidity of the grout.
3. Welding or Bolt Connection
   Commonly used for on-site assembly of large components. For arc welding, remove rust from the ends of the steel bars and control the weld length (not less than 10 times the diameter of the steel bar). For bolt connections, pre-drill holes and use high-strength bolts, suitable for scenarios that require disassembly or adjustment.
4. Mechanical Connection
   Connect steel bars through threaded sleeves or extrusion equipment. Ensure that the connection length is not less than 8 times the diameter of the steel bar, and clean oil and rust from the surface of the steel bars. After connection, check whether the threads are tightened or the extrusion is dense.

II. Construction of Post-Cast Joints in Prefabricated Walls

1. Selection of Joint Forms
   According to the position of the wall, adopt "I"-shaped (straight connection), "L"-shaped (corner connection), or "T"-shaped (cross connection) joints to ensure that the joint stress is coordinated with the overall structure.
2. Construction Steps
   • Stirrup Positioning: Mark the positions of stirrups on the prefabricated slab, place them in advance and fix them crosswise to prevent displacement during pouring.
   • Steel Bar Alignment: Adjust the positions of reserved vertical steel bars. When connecting upper steel bars, maintain verticality, and the deviation should be ≤ 5mm.
   • Surface Cleaning: Remove debris from the surface of the laminated slab to ensure that the spacing of steel bar binding meets design requirements (e.g., the deviation of the spacing of main steel bars should be ≤ ±10mm).
   • Binding Specifications: Bind steel bars according to the design layout lines. Place hooked steel bars downward to enhance tensile performance, and the ends of stirrups should be bent at 135°.

III. Application of Steel Bar Cages

1. Structural Characteristics
   Formed by welding main steel bars and stirrups into a ring-shaped supporting structure, with no reinforcement required in the central part. Commonly used in foundation construction such as pile foundations and bridge culverts. Calculate the diameter, spacing, and length of the main steel bars according to the design.
2. Manufacturing Process
   • Site Preparation: Set up a rain-proof and moisture-proof site, and cut the steel bars according to the design (the length deviation should be ≤ ±50mm).
   • Welding Processing: Control the positions of the main steel bars through positioning brackets, with a stirrup spacing deviation of ≤ ±20mm. After welding, stack them to a height of ≤ 2 meters and a number of layers of ≤ 3.
   • Construction Control: The sediment thickness should be ≤ 50mm, the buried depth of the tremie should be controlled between 2-6 meters, and the slump of the concrete should be 180-220mm to prevent the steel bar cage from floating.

Precautions:

• The connection method should be selected comprehensively based on the stress on the component, the climatic environment (e.g., anti-freezing grout should be used in low temperatures), and on-site conditions.
• After the acceptance of concealed works, temporary supports should be set up for main load-bearing components, and they can be removed only after the strength of the connected parts reaches 75% of the design value.
• Operators should receive technical training and strictly abide by safety regulations, such as wearing protective face shields during welding and fastening safety harnesses for high-altitude operations.