House Beam Modification: Removing Precast Panels

The removal of precast panels during house beam modification must strictly adhere to safety regulations and operational procedures. The specific steps and precautions are as follows:

I. Pre-demolition Preparation

1. Overall Safety Assessment
   A professional agency should be commissioned to conduct a comprehensive inspection of the building structure to confirm that the removal of precast panels will not affect overall stability. Particular attention should be paid to assessing the load-bearing capacity of the floor slab, the load-bearing capacity of the walls, and the connection status of adjacent components. If wall-to-beam modification is involved, a support plan should be designed in advance to ensure structural safety during the removal process.

2. Erect Temporary Support System

   • Set up steel pipe supports every 1.2 meters along the length of the precast panel, with key nodes using H-shaped steel beam underpinning (steel beam section ≥ 200*200 mm) to form a stable support framework.
   • The support system should extend to adjacent structures to avoid localized stress concentration leading to collapse.

II. Demolition Operation Steps

1. Cut Connecting Components

   • Use a rebar cutter or electric grinder to cut the connecting rebar, bolts, and other fasteners between the precast panel and the walls and beams.
   • Control the cutting depth during operation to avoid damaging the rebar in the surrounding structure.

2. Remove Precast Panels

   • Crushing Method: If the precast panel is small in size or space is limited, use a hydraulic breaker or pneumatic pick to crush it piece by piece, controlling the impact force and angle to prevent fragments from flying and injuring people or damaging the floor slab.
   • Lifting Method: If the precast panel is large in size (e.g., with a span exceeding 3 meters), use a crane with hooks to securely bind and slowly lift it to the ground. The binding points should be evenly distributed to avoid eccentric loading leading to fracture.

3. Clean and Inspect

   • Promptly clean up the crushed fragments and check whether there are any residual rebar or concrete protrusions on the floor slab surface, grinding them if necessary.
   • Confirm that the support system is free from looseness or deformation to create conditions for subsequent construction.

III. Key Precautions

1. Control Demolition Volume
   The daily demolition area should not exceed 30% of the total floor slab area to avoid structural settlement or cracking caused by sudden load changes.

2. Prohibit Impact Demolition
   It is strictly prohibited to use heavy hammers, pneumatic picks, or other high-impact tools to directly strike the precast panel to prevent vibrations from being transmitted to the foundation and affecting the overall stability of the building.

3. Real-time Monitoring and Emergency Response

   • Continuously monitor the stress changes in the support system during the demolition process and immediately stop work and reinforce if abnormalities are detected.
   • Equip the site with emergency rescue equipment, such as jacks and wooden wedges, for emergency support in case of sudden collapse.

4. Personnel Protection and Warning

   • Operators must wear safety helmets, cut-resistant gloves, protective goggles, and dust masks. High-altitude operations require safety harnesses.
   • Set up enclosures and warning signs in the work area to prohibit non-construction personnel from entering.

Summary: The removal of precast panels should focus on structural safety, ensuring construction safety and building stability through scientific assessment, standardized support, precise operation, and strict monitoring. Non-professionals should not attempt the operation擅自操作 (unauthorized operation) and are advised to commission qualified construction units for implementation.