Chongqing Banan Prefabricated House

Accident cases related to prefabricated houses in Banan, Chongqing, show that the construction of prefabricated slabs must strictly follow regulations; otherwise, serious consequences may occur. The following elaborates on the accident background, causes, and preventive measures:

Accident Background
On May 22, 2024, during a dilapidated building renovation project at No. 129 Dongquan Zheng Street, Dongwenquan Town, Banan District, Chongqing, workers encountered a collapse while chiseling and cleaning the cushion layer of the prefabricated slab floor on the second floor. This incident resulted in one death, three injuries, and direct economic losses of approximately 882,000 yuan. The accident exposed the safety risks associated with prefabricated slab structures during renovation, particularly the issue of structural instability caused by improper construction sequences.

Direct Causes of the Accident

1. Violation of Demolition Sequence: Workers did not follow the standard procedure of "removing walls first, then cleaning prefabricated slabs." Instead, they prematurely chiseled and cleaned the cushion layer and slab joints of the prefabricated slab floor while the brick balustrades on the outer side of the cantilever beams and balconies had not been fully removed.
2. Imbalanced Load Distribution: After the construction debris on top of the prefabricated slabs was prematurely cleared, the load pressing on the slabs decreased. This caused the overturning moment (the force causing the structure to flip outward) on the outer side of the cantilever beams to exceed the anti-overturning moment (the force resisting flipping) on the inner side, ultimately leading to the collapse.
3. Structural Characteristic Risks: Prefabricated slabs are prefabricated components. Compared with cast-in-place structures, they have weaker overall integrity and deformation resistance. Especially in cantilevered parts (such as balconies and overhanging beams), they are more sensitive to load changes, and construction disturbances can easily lead to instability.

Preventive Measure Recommendations

1. Strict Construction Sequence: When renovating prefabricated slab structures, the principle of "support first, then demolish; non-load-bearing first, then load-bearing" must be followed to ensure the gradual transfer of structural loads and avoid local overloading.
2. Strengthen On-site Monitoring: Conduct real-time monitoring of key areas such as cantilevered parts and connections of prefabricated slabs. If cracks, deformations, or other abnormalities are detected, stop work immediately and reinforce the structure.
3. Enhance Worker Training: Strengthen workers' understanding of the mechanical properties of prefabricated structures, clarify the serious consequences of non-compliant operations, and eliminate empirical operations.
4. Improve Safety Design: Before renovating dilapidated buildings, conduct a structural safety assessment. If necessary, add temporary supports or reinforcement measures to ensure the safety and controllability of the construction process.

This accident serves as a wake-up call for the construction of prefabricated houses. Comprehensive measures must be taken in terms of process standardization, technical support, and personnel management to effectively prevent similar risks.