High-Grade Seismic Resistance of Prefabricated Houses

The seismic resistance grade of prefabricated houses depends on the seismic fortification intensity during design, with significant differences in seismic resistance capabilities among different types, reaching up to a seismic fortification intensity of 9 degrees (corresponding to resistance against earthquakes of magnitude 7 - 9).

1. Old prefabricated panel buildings from the 1970s - 1980s

These houses were mostly designed according to the 'Code for Seismic Design of Buildings' (TJ 11 - 78), with a seismic fortification intensity generally of 6 - 7 degrees. Some areas, such as Beijing, were designed for a seismic fortification intensity of 7 degrees. Limited by the technological level at the time, the component connection methods were relatively simple, mostly using steel bar lapping or mortar jointing, resulting in poor overall integrity and weak seismic resistance of the houses. In earthquakes, these houses can usually withstand earthquakes of magnitude 6 - 7 (corresponding to an intensity of 6 - 7 degrees), but if they encounter an earthquake of magnitude 8 or above, they basically cannot guarantee safety and are at risk of overall collapse.

2. Modern prefabricated assembled buildings

Modern prefabricated assembled buildings are designed in accordance with the current 'Code for Seismic Design of Buildings' (GB 50011 - 2010), with a seismic fortification intensity that can reach 7 - 9 degrees, depending on the seismic fortification requirements of the area. These buildings adopt advanced technologies such as high-strength concrete, prestressed technology, and steel bar sleeve connections, significantly improving the overall integrity and seismic resistance of the houses. For example, assembled shear wall structures can withstand earthquakes of magnitude 8 or above, corresponding to resistance against earthquakes of magnitude 7 - 9. However, the actual seismic resistance capability also needs to be comprehensively evaluated in combination with design and construction quality.

3. Prefabricated panel structure houses

Prefabricated panel structure houses were mostly built before the 1990s, with weak seismic resistance capabilities, usually only able to withstand earthquakes below magnitude 4, and are considered buildings with substandard seismic performance. These houses are prone to swaying left and right during earthquakes, and the prefabricated panels are likely to fall off from the walls, leading to the overall collapse of the houses and posing serious safety hazards.

4. Supplementary information

Some believe that the seismic intensity index of prefabricated panel buildings should generally reach 7 degrees, and some areas, such as northern Xinjiang, even require it to reach 8 degrees (0.20g) to meet higher earthquake risk demands. This requirement reflects the differentiated standards for the seismic performance of prefabricated houses in different regions and further emphasizes the key role of seismic fortification intensity in house design.