Earthquake Resistance of Prefabricated Block Houses
Prefabricated panel houses can generally withstand earthquakes of magnitude 6 or so. Houses built before the 1980s can withstand earthquakes of intensity 6, while newly built ones can reach intensity 7, but their overall earthquake resistance is lower than that of reinforced cast-in-place houses. The following is an analysis from three aspects: earthquake resistance capacity, structural characteristics, and earthquake resistance weaknesses.
Differences in Earthquake Resistance Capacity
The earthquake resistance capacity of prefabricated panel houses is closely related to the construction era. Old-style prefabricated panel houses built before the 1980s, limited by the construction technology and material standards of the time, can usually only withstand earthquakes of intensity 6 (corresponding to moderate damage on the intensity scale). Newly built prefabricated panel houses, due to the adoption of improved connection techniques and materials, have their earthquake resistance capacity increased to intensity 7 (able to withstand relatively severe damage without the main structure collapsing). However, it should be noted that 'magnitude 6 earthquake' and 'intensity 6 earthquake' are different concepts. The former refers to the energy level released by the earthquake, while the latter refers to the impact of the earthquake on the ground surface and buildings. Both need to be comprehensively evaluated in combination with factors such as the focal depth and geological conditions.
Weak Overall Structure Due to Structural Characteristics
The earthquake resistance weakness of prefabricated panel houses stems from their 'building-block-like' structure. They are assembled from multiple prefabricated concrete panels connected by simple methods such as wire binding and cement mortar filling. There is a lack of effective steel bar anchoring or integral pouring connections between the panels, resulting in poor overall structural integrity. In contrast, reinforced cast-in-place houses form a continuous load-bearing system through on-site concrete pouring, enabling beams, panels, and columns to better disperse earthquake energy.
Earthquake Resistance Performance Limited by Materials and Design
The earthquake resistance capacity of prefabricated panel houses is also restricted by materials and design. Most prefabricated panels adopt a hollow design to reduce self-weight, but they have a small number of internal steel bars with uneven distribution. Compared with cast-in-place houses, the steel bars in prefabricated panels are thinner in diameter and have larger spacing, resulting in insufficient structural strength and toughness. When hit by seismic waves, the prefabricated panels are prone to disintegration due to connection failures or self-damage, and may even cause wall collapses. In contrast, the steel bar framework in cast-in-place houses is distributed in a three-dimensional manner, which can absorb energy through deformation and delay structural failure.
