How to Reinforce Prefabricated Slab Buildings

The reinforcement of prefabricated slab buildings should be carried out by selecting appropriate methods based on the actual safety appraisal results of the building. Common reinforcement methods are as follows:

When local bearing capacity is insufficient

• Carbon Fiber Adhesion: When the load increase is relatively small, carbon fiber can be directly adhered to the bottom of the hollow slab. Carbon fiber has the advantages of high strength and light weight, effectively improving the bearing capacity of the floor slab. Moreover, the construction is relatively simple and causes minimal damage to the original structure.
• Steel Beam Addition: Adding steel beams at the bottom of the slab changes the force mode of the hollow slab. It transfers part of the load to other structural components through the steel beams, thereby reducing the burden on the hollow slab and enhancing the overall structural stability.
• Section Steel Reinforcement Method: Install section steel along the four corners of the prefabricated slab to transform it into an octagonal support. This method effectively improves the bearing capacity of the floor slab. Through the support of the section steel, the floor slab distributes forces more evenly during loading, reducing local stress concentration.
• Plywood Reinforcement Method: Using mature techniques such as the plywood reinforcement method, by adding plywood to the surface or bottom of the floor slab, the overall stiffness and bearing capacity of the floor slab are improved, enhancing the seismic performance of the structure.

For specific situations (e.g., 30-year-old prefabricated slab buildings)

• Comprehensive Structural Safety Assessment: Focus on inspecting the crack width at the production area of the prefabricated slabs (special treatment is required if the width exceeds 0.3 millimeters) and detecting the connection status between the prefabricated slabs and the ring beams (replacement is necessary if the bolt corrosion rate exceeds 30%).
• Temporary Support System Construction: Set up steel pipe supports every 1.2 meters along the length of the prefabricated slabs. For key nodes, use H-shaped steel beams to replace the existing steel beams (the cross-section of the steel beams should be greater than or equal to 200*200 millimeters).
• Slab Joint Treatment: Remove the original filling material, implant No. 6 threaded steel bars, and pour C30 fine aggregate concrete.
• Constructional Column Addition: Add constructional columns at the four corners of the building (the cross-section of the constructional columns is generally 240*240 millimeters, with No. 6 and No. 8 steel bars tied together and connected to the floor slab).
• Construction Sequence: Adopt the principle of starting from the middle and then moving to the sides. Carry out segmental demolition and cutting, maintaining symmetrical demolition. The daily demolition volume should not exceed 30% of the total floor slab area. During the demolition process, continuously monitor the stress changes in the support system. It is prohibited to use heavy hammer impacts for demolition.

Other Situations

If there is only poor living experience without structural hazards, you can apply for subsidies for the renovation of old residential areas, repair cracks, replace pipelines, install insulation layers, etc., to improve the living environment.

Note: Reinforcement around prefabricated slab buildings is not suitable for all situations. Generally, it is not recommended for prefabricated slab buildings that have experienced fires or have structural cracks caused by foundation settlement.