Load-Bearing Test for Prefabricated Slab Houses

The load-bearing test for prefabricated slab houses is a crucial step in evaluating the safety of building structures, requiring systematic testing to determine whether their load-bearing capacity meets regulatory requirements.

1. Inspection Content

1. Structural System Inspection: Conduct a comprehensive inspection of the load-bearing structural system, structural layout and support system, and enclosure structural system to assess overall stability.
2. Material Performance Inspection:
   • Concrete Strength: According to the Technical Specification for Testing Concrete Strength by Core Drilling Method (CECS03:2007), use the core drilling method to sample and test the compressive strength of concrete in beams and columns.
   • Reinforcement Configuration: Based on the Technical Specification for Testing Reinforcement in Concrete (JGJ/T 152-2008), use a magnetic induction meter to inspect the diameter, quantity, and protective layer thickness of reinforcement in beams, slabs, and columns.
3. Crack and Damage Inspection: According to the Technical Specification for Inspection of Building Quality (DG/TJ08-79-2008), measure the width, location, and distribution of cracks to determine whether structural damage is caused by overloading or aging.
4. Geometric Dimension Inspection: Measure the cross-sectional dimensions of beams and columns, slab thickness, and floor plan layout to verify compliance with design drawings.
5. Appearance Quality Inspection: Observe whether the surface of the prefabricated slab is flat, free of honeycombing or deformation, and assess the impact of construction quality on load-bearing capacity.

2. Inspection Methods

1. Parameter Confirmation: Before the experiment, measure the length, width, and thickness of the prefabricated slab, and check the difference in thickness between the edges and the middle to avoid stress concentration caused by uneven thickness.
2. Loading Experiment:
   • Use equipment such as manual hydraulic jacks, electronic displacement meters, and cast iron weights to apply loads in a graded manner (e.g., increasing by 50 kg/m² per stage).
   • Record displacement data under different loads, observe whether micro-cracks or stress concentration phenomena occur at the bottom of the slab, and record crack propagation.
3. Dynamic Monitoring: Continuously monitor the deformation and crack development of the prefabricated slab during the experiment. If the crack width exceeds 0.2 mm or the displacement is abnormal, loading must be stopped immediately.

3. Load-Bearing Standard References

1. Conventional Load-Bearing Values:
   • The load-bearing capacity of ordinary concrete prefabricated slabs is approximately 500 kg per square meter (equivalent to the weight of 5 adults). National standards stipulate that the live load of residential floor slabs should not be less than 200 kg/m², and the total load-bearing capacity (including self-weight) can reach about 760 kg/m².
   • The load-bearing capacity of a 10 cm thick prefabricated slab is approximately 150-250 kg/m², and a 12 cm thick slab can reach 250 kg/m², depending on material strength, span, and construction techniques.
2. Special Scenario Limitations:
   • The static load of prefabricated hollow slabs used in factories in the 1990s should not exceed 400 kg/m², and the live load should not exceed 364 kg/m². Overloading may lead to cracks or collapse.
   • A concentrated load exceeding 20 tons (e.g., large equipment) may cause local collapse of the floor slab, necessitating reinforcement or load dispersion to reduce risks.

4. Precautions

1. Overloading Risk: When the load-bearing capacity exceeds 400 kg/m², cracks may appear in the prefabricated slab; if the concentrated load exceeds 20 tons, reinforcement measures must be taken immediately.
2. Impact of Construction Quality: Defects such as improper joint treatment and excessive cement plastering can significantly reduce load-bearing capacity, requiring focused inspection during testing.
3. Load Dispersion: If the weight of a single item exceeds 200 kg, a backing plate should be added to expand the受力面积 (load-bearing area) and avoid excessive local stress.