Prefabricated Concrete House Design

The design of prefabricated concrete houses requires systematic planning, covering three core aspects: preconditions, structural decomposition, and node connections. The specific plan is as follows:

I. Determination of Preconditions and Basic Parameters for Design

Key parameters must be defined based on climate, geological conditions, and building use. Taking a two-story rural self-built house as an example, the seismic fortification intensity is typically set at 7 degrees, with a basic wind pressure of 0.4 kN/m². The live loads for floors and roofs are designed at 2.0 kN/m² and 0.5 kN/m², respectively. Standardizing building modules is crucial for cost reduction; generally, 300 mm is used as the basic module. The bay can be 3.6 m, 3.9 m, or 4.2 m, the depth 4.5 m or 5.1 m, and the floor height is recommended to be 2.8 m or 3.0 m. With standardized modules, the variety of components decreases, mold turnover increases, and overall costs can be reduced by approximately 15%-20%.

II. Selection of Structural System and Decomposition of Prefabricated Components

The structural system should prioritize prefabricated monolithic concrete frame structures (for buildings up to three stories) or frame-shear wall structures (for high-rise buildings). In a pure frame structure, columns, beams, and slabs are all prefabricated, with node areas formed into a whole through post-poured concrete. The principles for component decomposition must consider transportation and lifting feasibility:

• Columns: Decomposed by floor, with common cross-sections of 400 mm × 400 mm or 500 mm × 500 mm;
• Beams: Main beams are decomposed at mid-span, with a cross-section of 300 mm × 600 mm, and secondary beams 250 mm × 500 mm;
• Floor slabs: Composite slabs are used, with a prefabricated base slab thickness of 60 mm, a cast-in-place layer thickness of 80 mm, and a total thickness of 140 mm;
• Stairs, balconies, and air conditioning panels: All prefabricated. Weight control is central to decomposition; the weight of a single component should be within 3-5 tons, with dimensions not exceeding transportation limits of 2.5 m in width and 4 m in height, ensuring lifting can be completed with a common truck crane.

III. Design of Node Connections

Node connections must ensure structural integrity and safety, with all connection methods requiring validation through finite element analysis and full-scale factory tests, with strength not less than that of the components themselves.

• Column-to-column connections: Use sleeve grouting connections. Vertical rebar is reserved at the top of the lower column, and grouting sleeves are embedded at the bottom of the upper column. During installation, they are aligned and inserted, and high-strength grout is injected through the grout hole to form continuous load-bearing rebar after the strength is achieved.
• Beam-to-column connections: Use corbel plates with post-poured concrete. The end of the prefabricated beam has a reserved slot, placed on temporary supports at the side of the column. The bottom rebar of the beam is welded to embedded parts in the column through anchor plates, with the top rebar lapped in the node core area. Finally, formwork is erected to pour C40 micro-expansion concrete, forming a rigid node.
• Floor slab-to-beam connections: Achieved by extending the胡子筋 (hooked rebar) at the end of the slab into the post-poured strip at the side of the beam, ensuring effective load transfer.

Through the above design, prefabricated concrete houses can achieve standardized production and efficient assembly, while meeting structural safety and economic requirements.