Prefabricated Panel House and Earthquake

Prefabricated panel houses perform poorly in earthquakes, with limited seismic resistance and significant safety hazards. The specific reasons are as follows:

I. Almost Zero Seismic Resistance
Prefabricated panel houses have poor integrity, with a structure similar to "building with blocks". The connections between panels and walls, as well as between panels themselves, are not secure, lacking rigid frameworks (such as ring beams and structural columns). During an earthquake, horizontal forces can cause the floor panels and walls to separate instantly, leading to the direct collapse of entire prefabricated panels, without any crack warnings or deformation buffers, leaving extremely short escape times. For example, most of the collapsed houses in the Wenchuan earthquake were of prefabricated panel structures.

II. Vulnerable Connection Points
Prefabricated panels are simply overlapped with walls, and the joint-filling process between panels is rough, failing to form effective connections. Foundation settlement and wall cracking can cause panel misalignment and loosening. Over time, weathering at connection points and steel bar corrosion further reduce strength. Old houses (such as those built in the 1970s and 1980s) are more prone to connection point failure due to low seismic standards at the time (only required to withstand magnitude 6 earthquakes), and even slight external forces (such as aftershocks) can trigger a chain collapse.

III. Substandard Material Quality
Some prefabricated panel production suffers from quality issues:

1. Steel Bar Substitution: Small workshops often use thin steel wires instead of standard steel bars, resulting in insufficient tensile strength;
2. Concrete Defects: The concrete grade does not meet standards, and the thickness is insufficient, making the material brittle and prone to cracking;
3. Poor Toughness: Compared to cast-in-place floor slabs, prefabricated panels lack toughness and can suddenly break under overload or aging, without any warning. Daily activities such as stacking heavy objects or renovation work that involves hitting the floor can accelerate damage.

IV. Discrepancies in Seismic Performance Data

• Theoretical Value: Newly built prefabricated panel houses using prestressed technology can have seismic resistance up to magnitude 7-9, but this is often compromised by cost-cutting measures by construction teams in practice;
• Actual Value: Most prefabricated panel houses can only withstand earthquakes of around magnitude 6, and houses built before the 1980s may only withstand intensity 6 earthquakes (a different concept from earthquake magnitude), with significantly lower seismic resistance than reinforced cast-in-place houses.

V. Policies and Legal Responsibilities
According to current policies, only D-grade dilapidated houses or prefabricated panel houses within urban core area plans are prioritized for demolition, with most old prefabricated panel houses being reinforced through renovation projects. If damage occurs due to collapse during an earthquake, according to the Civil Code:

• Quality Defects: The construction unit and the construction company bear joint liability;
• Management Responsibility: Owners, managers, or users who fail to fulfill their safety obligations are required to bear corresponding responsibilities.