Is Prefabricated Housing Earthquake-Resistant?
Whether prefabricated housing is earthquake-resistant depends on specific circumstances and cannot be generalized.
From the perspective of design specifications: Prefabricated houses built in the early days (before 1990) had relatively weak earthquake resistance. At that time, the old seismic design code TJ11 - 78 was mainly implemented, with low seismic standards and no clear “three-level seismic fortification” theory. In areas with a seismic intensity of 6 degrees, seismic structural measures were basically not required. Most houses lacked core seismic components such as structural columns and ring beams. The prefabricated slabs were directly placed on brick walls without overall connections. When an earthquake occurs, problems such as slab joint cracking and prefabricated slab detachment are prone to occur. 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 was also mandatory to set closed ring beams on each floor and structural columns at the four corners of the house and the four corners of the stairs, significantly improving the seismic performance.
From the perspective of construction quality: Even if the design complies with seismic codes, unauthorized design modifications and shoddy workmanship during construction can also reduce the seismic performance of the house. For example, reducing the number of structural columns and ring beams, using concrete with insufficient strength, or shortening the curing time can all affect the overall integrity and stability of the house, making it more vulnerable to damage in an earthquake.
From the perspective of construction year: Prefabricated slab houses can generally withstand earthquakes of around magnitude 6. Houses built before the 1980s, due to the low seismic standards at that time, can now withstand a maximum of a 6-degree earthquake. Newly built prefabricated houses can withstand a 7-degree earthquake, but there is still a gap in seismic performance compared to reinforced cast-in-place houses. Because prefabricated slabs are assembled like building blocks, their overall integrity is relatively poor, and they are prone to disintegration during earthquakes. Prefabricated slab buildings can withstand a maximum of a magnitude 7 earthquake, and there are significant differences between houses built in different eras. Old buildings from the 1970s and 1980s were only required to withstand a magnitude 6 earthquake according to the standards at that time. Now, new buildings with the addition of prestressed technology can withstand earthquakes of magnitude 7 - 9. However, this also depends on whether the construction team cuts corners.
