Replacement of Wall with Beam in Prefabricated Panel Houses

The replacement of walls with beams in prefabricated panel houses must strictly adhere to the following construction steps to ensure structural safety and construction quality:

1. Structural Safety Assessment
   Before construction, a comprehensive inspection of the house must be conducted, focusing on the crack width of the prefabricated panels (reinforcement is required if the width exceeds 0.3 mm) and the connection status with the ring beams (replacement is necessary if the bolt corrosion rate exceeds 30%). If structural damage is found in the prefabricated panels, priority should be given to repair or replacement to avoid the risk of collapse during subsequent construction.

2. Temporary Support System Setup
   Steel pipe supports should be installed every 1.2 meters along the length of the prefabricated panels, with key nodes using H-shaped steel beams with a cross-section of no less than 200*200 mm for underpinning. The support system must cover the entire construction area to ensure that the floor load is transferred to the foundation through the supports during the removal of walls or prefabricated panels, preventing local settlement or cracking.

3. Wall Treatment and Formwork Installation

   • If side walls or load-bearing walls need to be replaced with beams, temporary supports should be installed on both sides of the walls to prevent instability during removal.
   • After chiseling out the opening for the beam, install and secure the side formwork. The formwork must closely fit the opening to prevent concrete leakage during pouring.

4. Reinforcement and Concrete Construction

   • Panel Joint Treatment: Remove the original filling material, implant No. 6 deformed steel bars, and pour C30 fine aggregate concrete to enhance the joint strength between panels.
   • Beam Reinforcement Configuration: Use 25 mm deformed steel bars for the bottom reinforcement, with a stirrup density of 5 to 7 per meter (higher than the standard for new houses) to ensure the beam's shear resistance.
   • Concrete Pouring: Depending on site conditions, choose side formwork grouting (with inclined formwork or a small conveyor) or opening grouting (requiring removal of the prefabricated panel). After pouring, vibrate thoroughly to avoid honeycombing and pitting.

5. Constructional Column Addition
   Add constructional columns with a cross-section of 240*240 mm at the four corners of the house, using No. 6 and No. 8 steel bars for reinforcement and connecting them reliably to the floor. These columns enhance the overall rigidity of the house and resist horizontal loads such as earthquakes.

6. Demolition and Monitoring

   • Follow the principle of "middle first, then sides" for segmental demolition, with a daily demolition volume not exceeding 30% of the total floor area to avoid concentrated loads causing support system failure.
   • Continuously monitor the stress changes in the support system and prohibit the use of heavy hammers for demolition to prevent structural damage.

7. Curing and Acceptance

   • Beam Curing: Remove the side formwork after 24 hours, and cure the bottom formwork and supports for at least 15 days in summer and 20 days in winter, with continuous watering to maintain moisture.
   • Acceptance Process: The designer must cooperate with the owner for acceptance at each construction stage, focusing on checking the stability of the supports, the rationality of the reinforcement configuration, and the concrete strength to ensure compliance with structural safety standards.