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, span, thickness, reinforcement, and load distribution method. Here is a detailed analysis:

1. Significant differences in types and specifications
Concrete hollow slabs are commonly found in rural self-built houses and old residential areas. According to national standards, they are calculated based on uniformly distributed loads, with a bearing capacity of 200-250 kilograms per square meter. For example, a hollow slab that is 3.6 meters long and 0.6 meters wide has a total bearing capacity of approximately 432 kilograms, but concentrated stacking may cause cracking. Solid prefabricated slabs, with more reinforcement and higher concrete grades (such as C30 and above), can bear 250-300 kilograms per square meter and are often used in areas with heavier loads, such as kitchens and bathrooms. Prestressed prefabricated slabs generate prestress through the tensioning of high-strength steel wires, resulting in stronger crack resistance and bearing capacity. 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 drops to 250-300 kilograms per square meter, but it is still 20% higher than that of ordinary slabs with the same span.

2. Span directly affects bearing capacity
The shorter the span of the prefabricated slab, the stronger its bearing capacity. For example, a hollow slab with a span of 2.4 meters can bear 250 kilograms per square meter; when the span is 3.6 meters, the bearing capacity drops to 200 kilograms per square meter; if the span exceeds 4.2 meters, the bearing capacity may be only 150-180 kilograms per square meter. An increase in span leads to an increase in the stressed area of the slab, resulting in a decrease in the bearing capacity per unit area.

3. Thickness and reinforcement are key structural factors
In terms of thickness, a 10-centimeter-thick prefabricated slab has stronger bearing capacity than an 8-centimeter-thick one. Regarding reinforcement, the thicker the steel bar diameter and the smaller the spacing (such as 8-millimeter steel bars spaced 15 centimeters apart), the more significant the bearing capacity. For example, a solid slab with sufficient reinforcement can bear 300 kilograms per square meter, while an ordinary slab with insufficient reinforcement may only bear 200 kilograms per square meter.

4. Load type determines safety
Prefabricated slabs have good tolerance for uniformly distributed loads but are sensitive to concentrated loads. For example, a hollow slab that can bear 200 kilograms per square meter can handle the uniform spreading of 200 kilograms of sand without any problems, but if a 300-kilogram safe is placed within a 1-square-meter area, it may crack due to excessive local stress. In special cases, although a 4-meter prefabricated slab can bear 2 tons, if it is concentrated in the middle, it is prone to breakage after long-term use; if the 2-ton items are dispersed to both ends and placed close to the load-bearing walls, safety can be improved by increasing the support points.

5. Special cases require comprehensive evaluation
National standards stipulate that the live load of residential floor slabs should be at least 200 kilograms per square meter, and the actual total bearing capacity (including the self-weight of the floor slab) can reach 760 kilograms per square meter, but it is significantly affected by thickness: a 10-centimeter-thick slab can bear 150-250 kilograms, and a 12-centimeter-thick slab can reach 250 kilograms. In addition, the ultimate bearing capacity of ordinary concrete prefabricated slabs is approximately 500 kilograms per square meter (about the weight of 5 adults), but long-term overloading or structural aging will reduce safety.