Reinforcement of Hollow Prefabricated Slab Houses

Reinforcement of hollow prefabricated slab houses requires targeted measures for common defects, with common reinforcement methods including slab strengthening and hole reinforcement, as detailed below:

Slab Strengthening Methods

1. Fiber-Reinforced Strengthening Method (Wrapping Method)
   This method is suitable for scenarios where the slab surface exhibits significant deflection or small cracks due to heavy loads but still has repair value. The core procedures include:

• Crack Treatment: First, inspect structural cracks and seal those wider than 0.2mm to prevent separation between the reinforcement material and the substrate.
• Substrate Preparation: Mill the laying surface to remove loose layers and thoroughly clean it with high-pressure air or a cleaning agent to ensure it is free of oil and dust.
• Material Application: Spray an adhesive primer and, after it dries slightly, lay carbon fiber plates (CFRP) or glass fiber-reinforced mortar (GFRM). The plates should be cut according to the designed flexural length and staggered in layers to disperse stress. During laying, use specialized tools to press and exclude air and excess adhesive from the bottom.
• Surface Protection: Finally, apply a protective paint to prevent environmental factors such as UV rays and moisture from eroding the fiber materials. If further reinforcement is needed, pre-tensioning can be applied based on calculations to enhance the coupling effect between the composite and the structure.

2. Bonding Carbon Fiber Sheets
   When the load increase is minimal, carbon fiber sheets can be directly bonded to the bottom of the hollow slab. This method is simple to construct and suitable for repairing local insufficient bearing capacity, but it is essential to ensure compatibility between the adhesive and the substrate and fiber sheets to avoid debonding risks.

3. Adding Steel Beams
   Adding steel beams to the bottom of the slab can change the load-bearing system of the hollow slab, transferring part of the load to the walls or columns through the steel beams and significantly improving the overall stiffness of the slab. The specifications of the steel beams should be determined based on calculations, and reliable connections with the original structure must be ensured during installation to avoid local stress concentrations.

Hole Reinforcement Methods for Slabs
If the hole is located in the mid-span of the slab (the most unfavorable load-bearing area), equal-strength carbon fiber sheets should be bonded on both sides of the hole to compensate for the loss of flexural bearing capacity. Specific operations include:

• Carbon Fiber Sheet Cutting: Cut carbon fiber sheets of sufficient width according to the hole size and calculation results, ensuring coverage beyond the edges of the hole by a certain range.
• Bonding Construction: Bond the sheets according to the principle that the fiber direction is consistent with the load-bearing direction of the slab. When laying in layers, stagger the lap joints and use a roller to press and exclude air bubbles.
• Anchoring Treatment: Add U-shaped hoops or mechanical anchors at the ends of the carbon fiber sheets to prevent peeling failure.

Precautions: Before reinforcement, conduct a comprehensive inspection of the house to clarify the type and extent of defects; strictly adhere to specifications during construction to ensure material quality and workmanship meet standards; after reinforcement, perform bearing capacity calculations and long-term monitoring to ensure safety.