Are Prefabricated Houses Earthquake-Resistant?
Whether prefabricated houses are earthquake-resistant depends on specific circumstances and cannot be generalized.
Analysis from the perspective of design specifications: Prefabricated houses built before 1990 generally have weaker earthquake resistance. At that time, the old seismic design code TJ11 - 78 was mainly implemented, with relatively low seismic standards. The “three-level seismic fortification” theory was not clearly defined, and seismic structural measures were basically not required in areas with a seismic intensity of 6 degrees. Such houses often lack core seismic components such as structural columns and ring beams. The prefabricated slabs are directly placed on brick walls without overall connection, making them prone to problems such as slab joint cracking and slab detachment during earthquakes. After 1990, the implementation of the GBJ11 - 89 code and subsequent standards clearly required that prefabricated slabs must be connected with cast-in-place composite layers, and pure bare laying was prohibited. It also mandated the installation of closed ring beams on each floor and structural columns at the four corners and the four corners of stairs, significantly improving seismic performance.
Analysis from the perspective of construction year: Prefabricated slab houses can generally withstand earthquakes of around magnitude 6. Houses built before the 1980s can resist a seismic intensity of 6 degrees, while newly built ones can reach 7 degrees. However, even new houses are not as earthquake-resistant as reinforced cast-in-place structures because prefabricated slabs are like building blocks, with poor overall integrity and are prone to disintegration. Prefabricated slab buildings can withstand earthquakes of up to magnitude 7 at most. The old buildings from the 1970s and 1980s were only required to resist a seismic intensity of 6 degrees according to the standards at that time. Now, new buildings with prestressed technology can withstand earthquakes of magnitude 7 - 9.
Analysis from the perspective of construction quality: Construction quality has a significant impact on the seismic effect of prefabricated houses. Even if the design complies with seismic codes, if the construction擅自 (unauthorized) modifies the design or cuts corners, such as reducing the number of structural columns and ring beams, or using concrete with insufficient strength and shortening the curing time, the seismic performance of the house will be reduced. For example, structural columns and ring beams are key components that enhance the overall integrity and stability of the house. If their number is reduced, the house is more likely to deform and collapse during an earthquake. Insufficient concrete strength or shortened curing time will lead to a decrease in the load-bearing capacity of the components, making them unable to effectively resist seismic forces.
