Bearing Capacity of Prefabricated Slab Houses

The bearing capacity of prefabricated slab houses does not have a fixed value and is influenced by multiple factors such as type, specifications, span, materials, and construction. The bearing capacity ranges for common types are as follows:

I. Classification by Prefabricated Slab Type

1. Concrete Hollow Prefabricated Slabs: According to national standards, the uniformly distributed load is 200-250 kilograms per square meter. For example, a hollow slab that is 3.6 meters long and 0.6 meters wide has an area of 2.16 square meters. Its total bearing capacity is approximately 432 kilograms (2.16×200). It can evenly support 8 bags of 50-kilogram cement, but concentrated stacking can easily cause cracking.
2. Solid Prefabricated Slabs: They can bear 250-300 kilograms per square meter. Solid slabs produced by large factories can have a bearing capacity of up to 300 kilograms per square meter due to sufficient reinforcement and high concrete grades (C30 and above).
3. Prestressed Prefabricated Slabs: When the span is within 3 meters, they can bear 300-400 kilograms per square meter. When the span exceeds 4 meters, the bearing capacity remains at 250-300 kilograms per square meter, which is 20% higher than that of ordinary prefabricated slabs of the same span.

II. Key Factors Affecting Bearing Capacity

1. Span: The shorter the prefabricated slab, the stronger its bearing capacity. For example, a hollow slab with a 2.4-meter span can bear 250 kilograms per square meter, while a 3.6-meter span drops to 200 kilograms per square meter, and spans over 4.2 meters may only have a bearing capacity of 150-180 kilograms per square meter.
2. Thickness and Reinforcement: A 10-centimeter-thick prefabricated slab has a lower bearing capacity than a 12-centimeter-thick one. Slabs with thicker and more densely spaced steel bars (e.g., 8-millimeter steel bars spaced 15 centimeters apart) have stronger bearing capacities.
3. Load Type: Concentrated loads can easily crack the slab. For example, when the bearing capacity is 200 kilograms per square meter, evenly spreading 200 kilograms of sand is safe, but placing a 300-kilogram safe on 1 square meter may cause cracking.

III. Historical Standards and Normative References

1. In the 1970s and 1980s, the design value for live loads in residential buildings was 150 kilograms per square meter, considering a safety factor of 1.2 to 1.4.
2. National standards stipulate that residential floor slabs must be able to bear at least 200 kilograms of live load, and the total bearing capacity, including the self-weight of the floor slab, is approximately 760 kilograms.
3. Prefabricated slabs are classified into grades, with Grade I slabs having a standard value of 100 kilograms and Grade IV slabs having a value of over 400 kilograms.

In practical applications, it is necessary to comprehensively evaluate the bearing capacity based on factors such as the type of prefabricated slab, span, and load distribution to avoid overloading or concentrated stacking of heavy objects.