Are Houses in Wenchuan Prefabricated Panel Houses?
Many of the houses that collapsed during the Wenchuan earthquake were prefabricated panel houses. Here is a detailed analysis:
In the post-earthquake investigation of the Wenchuan earthquake, the structural flaws of prefabricated panel houses were clearly identified as one of the core reasons for the massive collapse of houses. Prefabricated panel houses are constructed by assembling prefabricated concrete panels. Their overall structural integrity is poor, and there is a lack of effective connections and coordinated force-bearing mechanisms among the components. Under the strong impact of seismic waves, this type of structure is prone to rapid disintegration due to joint damage and component separation, leading to the overall collapse of the house. For example, the houses in the Hangkong Huayuan Community in Weizhou Town, Wenchuan County, which were prefabricated structures built before the earthquake, suffered moderate damage in the May 12 earthquake and were classified as dangerous buildings. This case visually reflects the vulnerability of prefabricated panel houses during earthquakes.
From a technical perspective, the seismic performance of prefabricated panel houses is limited by their design era and construction standards. From the 1980s to the 1990s, prefabricated panel houses were widely used in residential construction due to their high construction efficiency and low cost. However, the design codes at that time did not adequately consider the effects of earthquakes, resulting in relatively weak seismic bearing capacity, deformation capacity, and energy dissipation capacity of the houses. During the Wenchuan earthquake, when these houses were subjected to high-intensity ground motion, the connection joints between the prefabricated panels and the walls, beams, and columns were prone to damage, leading to progressive collapse.
In addition, the collapse mode of prefabricated panel houses is typical. During an earthquake, the prefabricated panels may fall due to support failure or be crushed due to wall collapse, forming a 'story-yielding' mechanism and causing the overall collapse of the house in the vertical direction. This collapse mode not only causes direct casualties but also increases the difficulty of rescue operations due to the complex accumulation of debris.
After the Wenchuan earthquake, China revised its building seismic design codes, explicitly requiring that new buildings must meet the seismic fortification goals of 'remaining intact under minor earthquakes, being repairable under moderate earthquakes, and not collapsing under major earthquakes', and prohibiting the use of prefabricated panel structures with poor seismic performance in earthquake-prone areas. This adjustment has significantly improved the seismic capacity of subsequent buildings and reduced losses from similar disasters.
