Reinforcement Construction of Prefabricated Slab Houses

The following are common methods and key points for the reinforcement construction of prefabricated slab houses:

1. Section Enlargement Reinforcement Method
By adding a post-cast layer of reinforced concrete with a thickness of no less than 40mm on the surface or bottom of the prefabricated slab, a rigid floor or roof is formed. Surface pouring is a common choice. If a composite layer needs to be poured on the bottom of the slab, the bottom of the slab should be roughened and the喷射法 (jetting method) should be used for construction to ensure a tight bond between the new and old concrete. This method can significantly enhance the overall stiffness of the structure and is suitable for prefabricated slabs with insufficient load-bearing capacity.

2. Carbon Fiber Sheet Bonding Reinforcement Method
Structural adhesive is used to bond carbon fiber sheets along the span direction to the tensioned part at the bottom of the slab. Carbon fiber sheets have the characteristics of lightweight and high strength, which can improve the load-bearing capacity and stiffness of the structure without significantly increasing the weight of the original member or affecting the building's appearance. During construction, it is necessary to ensure that the carbon fiber sheets are fully bonded to the concrete surface to avoid voids.

3. Structural Load Path Modification Reinforcement Method
Beams and columns are added at the bottom of the prefabricated slab to reduce the bending moment of the slab by adjusting the load transfer path. During construction, steel pipe supports should be installed every 1.2 meters along the length of the prefabricated slab, and H-shaped steel beam underpinning (with a steel beam section of no less than 200×200 mm) should be used at key nodes to ensure the stability of the support system. This method is suitable for areas with large spans or concentrated loads.

4. Replacement of Prefabricated Slabs
High-strength and high-performance prefabricated slabs are selected to replace the original members, enhancing the overall strength of the house. For weak connection points (such as slab joints and nodes), additional connecting reinforcement or enhanced node construction is required to ensure coordinated work between the new and old members. Before replacement, the load-bearing capacity of the original structure should be evaluated to avoid local overloading.

5. Reinforcement After Opening Holes
After opening holes in the prefabricated slab, internal force analysis and load-bearing capacity verification should be carried out, and reinforcement methods should be selected according to the hole location. Common measures include implanting reinforcement, pouring C30 fine aggregate concrete, or bonding carbon fiber sheets for reinforcement to ensure uniform stress distribution around the hole.

Construction Process and Precautions

• Structural Safety Assessment: Before construction, comprehensively inspect the crack width of the prefabricated slab (cracks > 0.3 mm need treatment) and the connection status with the ring beam (bolts with a rust rate > 30% need replacement).
• Temporary Support System: Before demolition, set up supports, with a daily demolition volume of no more than 30% of the total floor area. Monitor stress changes in real-time and prohibit heavy hammer impacts.
• Slab Joint Treatment: Remove the original filling material, implant No. 6 threaded reinforcement, and pour C30 fine aggregate concrete.
• Addition of Constructional Columns: Add 240×240 mm constructional columns at the four corners of the house, with No. 6 and No. 8 reinforcement tied together and reliably connected to the floor.
• Technical Guidance and Acceptance: Designers should cooperate throughout the acceptance process to ensure that the construction complies with regulatory requirements.