How to Prefabricate House Bents

The prefabrication of house bents mainly includes steps such as site layout, formwork fabrication, and the prefabrication of columns, roof trusses, and thin-web beams, as detailed below:

Site Layout: Before prefabricating components, it is necessary to carefully plan the on-site layout of components and the travel route of the crane, clarifying the stacking order of stacked components. Prefabricated columns should be arranged on both sides of the foundation, parallel to the axis; roof trusses and thin-web beams should be arranged within the span, also parallel to the axis. This arrangement facilitates the smooth progress of subsequent construction and improves construction efficiency.

Formwork Fabrication:

• Surface Treatment: The surface of the formwork must be flat and level to ensure the accuracy and quality of the components. When prefabricating in layers, an isolation agent should be applied to the surface of the formwork or between the upper and lower layers of components, typically using felt or thick plastic sheeting, to prevent component adhesion.
• Stacked Column Construction: For columns constructed in layers, especially at the 'I' section, the lower column should be filled with sand and compacted to be level with the column surface. Then, bricks should be laid to form an 'I'-shaped mold, and cement mortar should be applied and smoothed to ensure the stability and accuracy of the columns.
• Roof Truss Formwork Fabrication: There are two methods for fabricating roof truss formworks. One method involves using bamboo woven panels to create a half-truss mold at the same scale, and each time, the formwork is fabricated by comparing it to the mold. The other method involves directly laying out and constructing a brick formwork on the base layer. The brick formwork should be 50-100mm wider than each side of the component, with a 20-30mm thick layer of cement mortar applied to its surface. Then, the outline of the roof truss should be marked on the cement mortar, and the excess mortar outside the component should be cut off and trimmed to the actual size of the roof truss.

Prefabrication of Columns, Roof Trusses, and Thin-Web Beams:

• Formwork Erection: Bamboo plywood formwork is generally used for on-site prefabricated components. During stacked construction, the formwork at the column corbel, column base, and column top should be erected to the top in one go. Similarly, the formwork at the intersection of the cast-in-place web member and the upper and lower chords of the roof truss should also be erected to the top in one go to ensure the integrity and accuracy of the components. At the same time, the elevation of embedded reinforcement or pre-embedded parts must be accurate to avoid affecting subsequent construction.
• Lifting Ring Installation: The lifting point location of the column lifting ring and the diameter of the lifting ring reinforcement should be determined by the construction unit after comprehensive consideration and calculation based on several factors, including the lifting point location, the flexural strength and crack resistance of the component, the tensile strength of the reinforcement, the pulling force, and the local bearing strength, to ensure safety and stability during the lifting process.