Collapse of Prefabricated Floor Slab Buildings

The main reasons for the collapse of prefabricated floor slab buildings include structural defects, non-compliant construction operations, overloading, and management deficiencies, as analyzed in detail below:

1. Structural Defects: Poor Integrity and Weak Earthquake Resistance of Prefabricated Floor Slab Buildings

Prefabricated floor slab buildings often adopt a structural form with brick walls bearing the load and prefabricated hollow slabs as the floor. This structure is known as a "brittle failure" system in engineering. The core issue lies in insufficient integrity: there is a lack of effective connections between the prefabricated slabs and the walls, which are only fixed with mortar or simple anchoring. In the event of earthquakes, explosive impacts, or local damage, it can easily trigger a chain collapse. For example, in the collapse incident of the Railway 55 Dormitory in Xinhua District, Shijiazhuang, a gas explosion caused local structural failure, leading to the rapid collapse of the entire building and exposing the vulnerability of prefabricated floor slab buildings under extreme conditions.

2. Non-compliant Construction Operations: Improper Demolition Sequence or Lack of Support

Non-compliant operations during construction are direct causes of collapses. For example:

• In the accident in Dongwenquan Town, Banan District, Chongqing, demolition workers did not follow the sequence of "demolishing walls first and then clearing floor slabs". Without removing the brick balustrades on the outer side of the cantilever beams, they proceeded to chisel the prefabricated slab bedding first, causing an imbalance in the load distribution. The overturning moment of the cantilever beams exceeded their anti-overturning capacity, ultimately triggering the collapse.
• In the accident on Chaozong Street, Kaifu District, Changsha, construction workers continuously chiseled away 0.5 meters (of the total height) of the door frame columns without taking support measures for the load-bearing beams, causing the walls to lose support and collapse. Such operations directly undermined the structural stability and exposed loopholes in construction safety management.

3. Overloading: Temporary Accumulation of Heavy Objects Leading to Floor Slab Fractures

The design load-bearing capacity of prefabricated floor slabs is limited. If heavy objects are temporarily stacked or the slabs are overloaded, brittle fractures can easily occur. For example, in the accident in Guanba Town, Zhong County, Chongqing, the floor slab on the second floor fractured and fell due to a temporary accumulation of loads exceeding its design capacity, resulting in casualties. Such accidents often occur in old buildings where the prefabricated slabs have further decreased in load-bearing capacity due to long-term use or material aging.

4. Management Deficiencies: Failure to Implement Safety Production Responsibilities

The inadequate implementation of the main responsibility for safety production by enterprises is an indirect cause of accidents. For example, in the accident in Banan District, Chongqing, the involved enterprise did not clarify the safety production responsibilities of the demolition workers and did not conduct safety education and training, resulting in workers' insufficient awareness of operational norms and risks. Additionally, the lack of regular inspections and maintenance of old buildings allowed structural hazards to persist, ultimately leading to tragedies.