Construction of Prefabricated Beams for Houses
The construction of prefabricated beams for houses mainly includes steps such as formwork and pedestal preparation, steel bar processing and installation, formwork installation, concrete pouring, prestressed construction, beam removal, and storage. Modern production also introduces intelligent technologies to enhance efficiency.
Formwork and Pedestal Preparation: The pedestal is poured with reinforced concrete, and the bottom formwork uses stainless steel plates with camber set according to design requirements. The pedestal is provided with tie rod预留孔 (reserved holes for tie rods) every 5 cm to provide a stable foundation for subsequent construction.
Steel Bar Processing and Installation: The bottom and web steel bars are welded and formed on a binding jig, and the web corrugated pipes are also welded and formed with the bottom and web steel bars at this stage. Subsequently, the bottom and web steel bars are hoisted onto the box girder formwork where the side formwork has been installed. High-strength mortar blocks are used to control the concrete cover of the steel bars, ensuring accurate positioning of the steel bars and compliance with the required concrete cover thickness.
Formwork Installation: Side and core formworks are installed using a gantry crane in conjunction with manual labor, and formwork release agents are applied. Gaskets are placed between formwork joints to prevent grout leakage. After the web steel bars are hoisted, the bottom end formwork and core formwork are installed. After the core formwork is installed, the top plate steel bars are hoisted. After the top plate steel bars are hoisted, the top plate anchor slot formwork is installed, with attention paid to embedding reinforcement for the side span expansion joints, side plate crash barriers, and other embedded parts.
Concrete Pouring: Pouring is carried out using a gantry crane, progressing from one end to the other, with layer thickness not exceeding 30 cm. The bottom and web plates are vibrated using external vibrators, while the top plate and areas above the web corrugated pipes are vibrated using immersion vibrators. After pouring, automatic spray maintenance is promptly carried out, with a maintenance period of no less than 7 days. For prefabricated box girders, the concrete strength is typically C50, with each beam requiring 42 cubic meters of concrete. The bottom plate concrete needs to flow through the web plates, imposing high requirements on the "fluidity" and "cohesiveness" of the material.
Prestressed Construction: Prestressed steel strands must not be tensioned until the strength of the concrete test blocks under the same conditions reaches at least 75% of the designed concrete strength grade and the concrete age is not less than 7 days, subject to the approval of the supervisor. The steel strands of the prefabricated beams are tensioned using intelligent tensioning equipment, following the designed tensioning sequence with symmetric tensioning from both ends. After tensioning, anchor sealing is carried out, and the duct is grouted with a special grouting material or grouting agent.
Beam Removal and Storage: Beams can be removed and transported only when the strength of the duct cement grout reaches at least 30 MPa. Components should be stacked according to the hoisting and installation sequence and placed on skids during storage. No more than two layers of beams should be stored, and the storage time should not exceed 3 months.
Modern prefabricated beam production also introduces intelligent circular production lines and digital twin technology, utilizing mobile pedestals, hydraulic formworks, intelligent vibration systems, and steam curing processes to achieve full-process automation, significantly improving production efficiency.
