Prefabricated Panel Houses in Sichuan Earthquake

In the Sichuan earthquake, old prefabricated panel buildings exhibited weak seismic resistance, revealing numerous issues, while modern prefabricated buildings demonstrated significantly improved seismic performance. Detailed analysis is as follows:

1. Differences in Seismic Resistance of Prefabricated Panel Buildings
Old prefabricated panel buildings from the 1970s to 1980s were designed primarily according to the "Building Seismic Design Code" (TJ 11-78) of that time, with a seismic fortification intensity generally ranging from 6 to 7 degrees. Limited by the technological conditions of the time, component connections often employed simple steel bar overlaps or mortar joints, resulting in poor overall integrity and weak seismic resistance. For example, during the 2008 Wenchuan earthquake (with an intensity of 8-11 degrees), a large number of old prefabricated panel buildings collapsed, exposing their vulnerability under high-intensity earthquakes. In contrast, modern prefabricated buildings are designed according to the current "Building Seismic Design Code" (GB 50011-2010), with seismic intensities reaching 7-9 degrees depending on regional fortification requirements. They utilize high-strength concrete, prestressed technology, steel bar sleeve connections, etc., significantly enhancing overall integrity and seismic performance, enabling effective resistance to high-intensity earthquakes.

2. Hazards of Prefabricated Panel Brick-Concrete Structures
Seismic damage surveys from the Wenchuan earthquake revealed significant defects in prefabricated panel brick-concrete structures. Their overall structural connection and seismic performance were poor, with prefabricated panels, staircase landings, and exterior walls being the main causes of collapse and casualties. Such structures were prone to overall failure during earthquakes, leading to severe consequences.

3. Key Factors Affecting Seismic Resistance
Connection quality is the core factor determining the seismic resistance of prefabricated panel structures. If the connections between prefabricated panels and walls or beams are poorly welded or have poor pouring quality, the seismic performance of the structure will be significantly reduced. Additionally, if a building already has cracks, it is more prone to damage during earthquakes, further weakening its seismic resistance.

4. Reinforcement and Assessment Measures
For old prefabricated panel buildings, reinforcement can be carried out through methods such as attaching steel plates or adding shear walls, improving seismic resistance by 1-2 grades. However, in high-intensity areas above 8 degrees, safety must be determined through professional assessment. If deemed unsafe, demolition and reconstruction should be carried out. The "Technical Regulations for Emergency Assessment of Building Safety After Earthquakes" (DBJ51/T068-2016) issued by Sichuan Province provides technical guidance for the safety assessment of buildings after earthquakes, aiding in scientific decision-making.