Prefabricated Floor Slabs in Qiuyuan Community Houses

The prefabricated floor slab structures in the houses of Qiuyuan Community have issues such as easy aging at the joints and poor earthquake resistance. Improper renovation may lead to serious safety hazards, and renovation should be based on safety appraisal results.

Characteristics and Potential Risks of Prefabricated Floor Slab Structures

The houses in Qiuyuan Community are brick-concrete structures built in 2001, using prefabricated floor slabs. These slabs are assembled from factory-prefabricated cement components, with the core defect being that the joints rely on mortar for bonding. Mortar aging can cause joint cracking and debris shedding, leading to floor slab shaking and water leakage. Additionally, the connection strength between the prefabricated slabs and the walls is relatively low. Their earthquake resistance is significantly weaker than that of cast-in-place floor slabs. During an earthquake, the slabs and walls are prone to separation, resulting in structural instability.

Direct Impact of Renovation Behavior on Structural Safety

In a case, the upstairs resident knocked out the cement base layer of the dining room floor (about 5-6 centimeters thick), directly damaging the original load-bearing system of the floor slab. The cement base layer is an important part of the prefabricated slab structure, responsible for load transfer and distribution. After removal, the floor slab becomes thinner and less rigid, causing cracks in the ceiling and walls downstairs. Such behavior constitutes unauthorized alteration of the house's load-bearing structure and may trigger the following chain reactions:

1. Local stress concentration: After the floor slab becomes thinner, the load concentrates on the remaining part, accelerating joint cracking;
2. Overall stability decline: Changes in the load-bearing structure may lead to house tilting or settlement;
3. Waterproof layer damage: Removal of the cement layer may damage the waterproof layer, causing leakage.

Renovation Policies and Implementation Paths for Prefabricated Slab Houses

According to the "15th Five-Year Plan for Urban Renewal," the renovation of prefabricated slab houses mainly focuses on "repair and reinforcement" and "self-initiated renewal." Only D-grade dilapidated houses (with overall failure of the load-bearing structure and at risk of collapse at any time) will be forcibly demolished. Among the existing prefabricated slab residential buildings nationwide, D-grade dilapidated houses account for less than 4%. The remaining houses need to determine the renovation method through professional safety appraisals:

• Repair and reinforcement: For non-dilapidated houses, methods such as carbon fiber reinforcement and adding support columns are used to enhance structural safety;
• Self-initiated renewal: Homeowners can apply for in-situ reconstruction or functional upgrades, but they must comply with planning requirements and go through the approval process.

Tip: Homeowners should consult a structural engineer before renovation to avoid damaging load-bearing components. If cracks, deformations, or other abnormalities are found in the house, they should immediately commission a professional institution for inspection and take reinforcement measures.