Seismic Resistance of Prefabricated Panels in Housing

The seismic resistance of prefabricated panel buildings typically reaches a seismic intensity of 6-7, corresponding to an earthquake magnitude of about 6, with some areas adhering to stricter standards achieving a seismic intensity of 7 (magnitude 7 earthquake). However, their overall seismic performance is weaker than that of cast-in-place concrete or steel structures, and older buildings pose higher risks.

1. Basic Indicators of Seismic Resistance

The seismic resistance of prefabricated panel buildings primarily depends on design codes and construction standards. According to current codes, the seismic intensity of newly constructed prefabricated panel buildings is typically 6-7, corresponding to an earthquake magnitude of about 6. In some areas with stringent design requirements (such as Beijing), the seismic intensity index can reach 7 (i.e., capable of withstanding a magnitude 7 earthquake). However, it is important to note that seismic intensity and earthquake magnitude are different concepts: intensity reflects the degree of damage caused by an earthquake to the ground surface and buildings, while magnitude indicates the amount of energy released by the earthquake. In the same earthquake, the closer to the epicenter, the higher the intensity.

2. Seismic Weaknesses of Prefabricated Panel Structures

Prefabricated panel buildings are constructed by assembling prefabricated concrete panels, resulting in poor overall integrity and ductility, which leads to weaker seismic resistance compared to cast-in-place concrete or steel structures. Specific manifestations include:

1. Insufficient Structural Integrity: Prefabricated panels are connected through splicing, and the quality of gap treatment and steel bar connections directly affects structural stability. If construction is not standardized (e.g., insufficient steel bar anchorage length, unfilled splicing gaps), problems such as floor slab misalignment and wall cracking may occur during earthquakes.
2. Material Strength Limitations: Some prefabricated panels adopt a hollow design, with a lower steel bar density than cast-in-place structures, resulting in weaker structural strength and shear resistance. Under strong earthquakes or high winds, local damage or even collapse may occur.

3. Seismic Risks of Older Prefabricated Panel Buildings

Prefabricated panel buildings constructed before the 1980s generally have poorer seismic resistance due to lower design standards and material aging (e.g., concrete carbonation, steel bar corrosion). For example, the seismic intensity of early prefabricated panel buildings may only be 6, while similar newly constructed buildings can be upgraded to 7 through structural optimization (e.g., adding structural columns and ring beams). The risk of severe damage to older buildings during high-intensity earthquakes is significantly higher than that of newly constructed buildings.

4. Key Factors for Improving Seismic Resistance

The seismic performance of prefabricated panel buildings highly depends on design codes and construction techniques:

• Design Codes: Strictly adhering to seismic design standards (such as the Code for Seismic Design of Buildings) and reasonably setting seismic components such as structural columns and ring beams can enhance structural integrity.
• Construction Quality: Ensuring that the gaps between prefabricated panels are tightly filled and that steel bar connections are secure can prevent the weakening of seismic resistance due to construction defects.
• Regular Maintenance: Conducting seismic assessments and reinforcements (e.g., adding steel supports or carbon fiber cloth reinforcement) on older buildings can effectively improve their seismic performance.