Reinforcement Plan for Prefabricated Concrete Houses

Reinforcement of prefabricated concrete houses requires targeted methods based on the type of structural issues. Common reinforcement plans are as follows:

1. Reinforcement methods for insufficient load-bearing capacity

• Carbon fiber sheet reinforcement: Suitable for situations where the flexural load-bearing capacity of floors and beams is insufficient. High-strength carbon fiber sheets are pasted on the tensioned surface of the components, forming a composite structure through epoxy resin adhesive bonding, which can increase the flexural capacity of the components by 20%-50%. This method does not increase the cross-sectional size, does not affect the usable space, has a short construction period (usually 3-5 days), but requires ensuring that the base layer is treated smoothly to avoid voids.
• Steel plate bonding reinforcement: For weak node connections, steel plates (usually 4-8mm thick) are pasted at the junctions of panels and walls, achieving steel-concrete collaborative load-bearing through structural adhesive. This method can significantly enhance the overall integrity of the nodes and is suitable for areas with high seismic fortification requirements. However, attention should be paid to the anti-rust treatment and anchoring measures of the steel plates.
• Section enlargement reinforcement method:
  • Prefabricated panels: Add a reinforced concrete post-pouring layer not less than 40mm thick on the panel surface or bottom. Pouring a composite layer on the panel surface can form a rigid floor covering, while the post-pouring layer at the panel bottom should preferably be constructed using the spraying method (with a concrete strength grade not lower than C25). A Φ6@150 two-way steel mesh should be set.
  • Cast-in-place panels: Add a composite layer on the panel surface or a post-pouring layer sprayed at the panel bottom. The construction requirements are the same as those for prefabricated panels, and attention should be paid to the interface treatment between the new and old concrete (such as chiseling and applying interface agents).

2. Reinforcement methods for insufficient seismic performance

• Adding structural columns and ring beams: Add reinforced concrete structural columns (with a cross-sectional size of ≥240mm×240mm and reinforcement of 4Φ12+Φ6@200) at the junctions of walls and ring beams (with a height of ≥180mm and reinforcement of 4Φ10+Φ6@200) at the floor level to form an overall framework and enhance the spatial stiffness of the house.
• BFRM basalt fiber toughness mortar reinforcement: Suitable for seismic reinforcement of masonry walls, with a single-sided plastering thickness of only 15-30mm and a self-weight of 30-50kg/㎡. It can reach the design strength after 7 days of curing. This method is convenient for construction and has little impact on space, but strict control of the mortar mix ratio and construction temperature (5-35℃) is required.
• Steel mesh mortar surface layer reinforcement: For insufficient load-bearing capacity of brick masonry walls, apply a 20-30mm thick cement mortar layer on one or both sides of the wall and configure a Φ4@200 two-way steel mesh. This method can increase the shear capacity of the wall by 30%-50%, but attention should be paid to the reliable connection between the steel mesh and the wall (such as using S-shaped wall-penetrating reinforcement).

3. Reinforcement methods for foundation issues

• Grouting foundation reinforcement: If there is uneven settlement of the foundation, the pressure grouting method (using cement slurry or chemical slurry) can be used to fill the voids in the soil layer and increase the bearing capacity of the foundation. The spacing between grouting holes should be 0.8-1.5m, and the grouting pressure should be controlled at 0.2-0.5MPa. The mix ratio of the slurry and the standard for terminating grouting should be determined through experiments.

Implementation points: Before reinforcement, a professional institution should be commissioned to conduct a structural safety appraisal to clarify the damaged parts and their degrees. During the construction process, standards such as the "Code for Design of Reinforcement of Concrete Structures" (GB50367) should be strictly followed. After reinforcement, acceptance and long-term monitoring (such as settlement observation and crack inspection) should be carried out.