Safety Performance of Prefabricated Panel Houses

The safety performance of prefabricated panel houses presents significant issues, primarily reflected in poor earthquake resistance, fragile connection points, and shoddy material usage, along with key points for identifying structural hazards and risks associated with unauthorized modifications.

Poor Earthquake Resistance

Prefabricated panel houses have poor overall integrity and are prone to disintegration during earthquakes. Their seismic performance is significantly inferior to that of cast-in-place reinforced concrete houses: older houses built before the 1980s can only withstand earthquakes of magnitude 6, while newly constructed prefabricated panel houses have been upgraded to magnitude 7, but still fall short of cast-in-place houses. This difference stems from the lack of continuity in prefabricated panels compared to cast-in-place structures, making them susceptible to component dislocation or fracture under seismic waves.

Fragile Connection Points

Prefabricated panels are fixed to walls through simple overlaps, with gaps between panels lacking rigid connections and generally lacking reinforcing structures such as ring beams and structural columns. Ground settlement, wall cracking, or material aging (e.g., steel corrosion, concrete weathering) directly weaken the strength of connection points, potentially leading to partial or complete collapse in extreme cases.

Shoddy Material Usage

Some prefabricated panel production involves violations: using thin steel wires instead of reinforcing bars, substandard concrete grades, and insufficient panel thickness, resulting in high structural brittleness and weak impact resistance. When loads exceed design limits, prefabricated panels may suddenly fracture without warning, posing a severe threat to occupant safety.

Key Points for Identifying Structural Hazards

1. Foundation: Check for ground settlement around the house, abnormal height differences between indoor and outdoor ground levels, and diagonal cracks at the base of walls.
2. Prefabricated Floor Panels: Observe whether there are horizontal through-cracks or joint cracks in the ceiling, whether the middle of the floor panel sags or deforms, and whether there is concrete looseness or steel corrosion at the panel ends.
3. Load-Bearing Walls: Examine walls for vertical or diagonal cracks, whether there are cracks or downward pressure at door and window lintels, and whether the bottom layer of wall roots is weathered or flaking.
4. Node Connections: Confirm whether the supports for prefabricated panels are secure and free from looseness, and whether there are disconnections or cracks at wall corners or intersections.

Risks Associated with Unauthorized Modifications

Removing or altering load-bearing walls, adding structures to rooftops, installing additional floors, stacking heavy objects on floor panels, or changing the purpose of the house (e.g., converting residential use to commercial use) significantly reduce structural safety. Such actions may disrupt the original load-bearing system, leading to insufficient local or overall load-bearing capacity and even collapse accidents.

In conclusion, prefabricated panel houses require regular structural safety assessments, avoidance of unauthorized modifications, and priority consideration for reinforcement or reconstruction in earthquake-prone areas.