How is the Seismic Performance of Prefabricated Houses?
The seismic performance of prefabricated houses depends on specific circumstances and cannot be generalized. It is influenced by various factors such as design, performance comparison, and construction.
From a design perspective, early prefabricated houses had relatively weak seismic performance. Most of the prefabricated houses built before 1990 followed the old seismic code TJ11 - 78, which had relatively low seismic standards. At that time, the 'three-level seismic fortification' theory was not clearly defined, and seismic structural measures were generally not required in areas with a seismic intensity of 6 degrees. Such houses often lacked core seismic components such as structural columns and ring beams. The prefabricated slabs were directly placed on brick walls without overall connections. In earthquakes, problems such as slab joint cracking and slab detachment were prone to occur. However, the GBJ11 - 89 code implemented after 1990 and subsequent standards clearly required that prefabricated slabs must be connected with cast-in-place composite layers, and pure bare laying was prohibited. They also mandated the installation of structural columns at the corners of each floor's closed ring beams and at the corners of stairs, significantly improving seismic performance.
In terms of performance comparison, the seismic performance of prefabricated slab houses is lower than that of reinforced cast-in-place houses. Prefabricated slabs are like building blocks, with poor overall integrity, and are prone to disintegration under seismic action. Generally, newly built prefabricated slab houses can withstand earthquakes of magnitude 7, while old houses built before the 1980s can only withstand earthquakes of magnitude 6.
From a construction perspective, construction quality has a huge 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, it will also reduce the seismic performance of the house. For example, reducing the number of structural columns and ring beams, or having insufficient concrete strength and shortened curing times, will significantly reduce the house's ability to withstand earthquakes.
Therefore, the seismic performance of prefabricated houses cannot be simply determined. It is necessary to comprehensively consider various factors such as design codes, construction years, house types, and construction quality to accurately assess their seismic capacity.
