Reinforcement and Maintenance of Prefabricated Slab Houses
The reinforcement and maintenance of prefabricated slab houses should select appropriate methods based on the actual condition of the house. Common reinforcement and maintenance methods are as follows:
Structural Inspection and Assessment
A comprehensive structural safety assessment of the old house is the foundation for reinforcement and maintenance. Focus on inspecting the crack width at the production site of the prefabricated slabs. If the width exceeds 0.3 millimeters, special treatment is required, such as grouting repair or reinforcement with carbon fiber sheets. At the same time, inspect the connection status between the prefabricated slabs and the ring beams. If the bolt corrosion rate exceeds 30%, the bolts should be replaced in a timely manner to ensure connection reliability.
Bottom Slab Reinforcement Measures
When the load increase is relatively small, carbon fiber sheets can be directly pasted on the bottom of the hollow slabs to enhance their load-bearing capacity by utilizing the high strength of carbon fiber. If the load increase is significant, steel beams can be added at the bottom of the slabs. By adding new steel beams, the stress system of the hollow slabs is changed, and the load is distributed to the steel beams, reducing the burden on the original slabs. The cross-section of the steel beams should be determined according to calculations, generally not less than 200*200 millimeters. H-shaped steel beams are used for key nodes to ensure a clear load transfer path.
Wall Reinforcement Treatment
Remove the original exterior wall tiles and carry out repainting and steel bar planting and grouting treatment on the exterior walls. When planting steel bars, drill holes, clean the holes, inject adhesive, and plant the steel bars according to specifications to ensure a reliable connection between the steel bars and the walls. High-strength non-shrink grouting materials should be selected for grouting to enhance the load-bearing strength and tensile properties of the walls and prevent cracking due to increased loads or seismic action.
Slab Joint and Structural Column Reinforcement
For the slab joint positions detected during the structural inspection, remove the original filling materials, implant No. 6 threaded steel bars with the spacing arranged according to design requirements, and then pour C30 fine aggregate concrete to enhance the shear resistance of the slab joints. Add structural columns at the four corners of the house. The cross-section of the structural columns is generally 240*240 millimeters, with No. 6 and No. 8 steel bars used for reinforcement. The steel bars are anchored into the floor slab and the foundation, forming an integral whole with the floor slab to improve the overall integrity and seismic performance of the house.
Construction Process Control
During the construction preparation stage, a temporary support system should be erected, with steel pipe supports set every 1.2 meters along the length of the prefabricated slabs. H-shaped steel beams are used for key nodes to ensure structural safety during construction. When dismantling, follow the principle of 'from the middle to the sides', carry out dismantling and cutting in sections, and maintain symmetrical dismantling. The daily dismantling amount should not exceed 30% of the total floor slab area. During the dismantling process, monitor the stress changes in the support system in real-time. It is prohibited to use heavy hammer impact for dismantling to avoid shock and damage to the foundation structure. If holes need to be drilled in the floor slab for pipe installation and the hole location is at the mid-span of the floor slab, carbon fiber sheets of equal strength can be pasted on both sides of the hole to prevent insufficient load-bearing capacity of the slab due to the hole.
