Reasons Why Prefabricated Houses Are Not Earthquake-Resistant
The main reasons why prefabricated houses are not earthquake-resistant include deficiencies in connection methods, structural design, and material properties.
Firstly, the splicing method of prefabricated panels results in poor structural integrity. Traditional cast-in-place reinforced concrete structures form a continuous whole through on-site pouring, with the steel bars between the floor slabs and walls fully anchored by the concrete, creating a stable load-bearing system. In contrast, the floor slabs of prefabricated houses are typically composed of multiple prefabricated panels spliced together, with connections between panels made only at nodes (such as welding, bolt fixation, or concrete grouting). The mechanical properties of this connection method are significantly weaker than those of cast-in-place structures. Under seismic action, cracks can easily form at the splices due to repeated tension and compression, and even misalignment or separation can occur, leading to a loss of structural integrity and an inability to effectively transmit seismic forces.
Secondly, prefabricated panels often adopt a hollow design to reduce weight and cost, resulting in insufficient steel bar reinforcement. The density and distribution of steel bars in cast-in-place structures are strictly calculated to form a multi-dimensional load-bearing framework that enhances the concrete's crack resistance and deformation resistance. However, to reduce self-weight (for ease of transportation and installation) and material costs, prefabricated panels are often designed as hollow structures with fewer internal steel bars and uneven distribution. For example, some prefabricated panels have thin steel bar diameters, large spacing, or steel bars configured only at the edges of the panels, with the central area lacking effective reinforcement. This design makes the prefabricated panels prone to fracture due to local stress concentration during earthquakes, and after fracture, they cannot consume seismic energy through the ductility of the steel bars, exacerbating structural damage.
Finally, prefabricated panels have a low seismic coefficient and weak resistance to deformation. The seismic coefficient is a key indicator for measuring a structure's ability to maintain integrity during an earthquake and is closely related to the strength, toughness, and connection method of the materials. Due to deficiencies in the splicing nodes and steel bar reinforcement, the seismic coefficient of prefabricated panels is usually lower than that of cast-in-place structures. Under the repeated action of seismic waves, prefabricated panels are prone to bending, shearing, or torsional deformation, which can lead to floor slab collapse or wall collapse when exceeding their load-bearing capacity. In addition, the overall stiffness distribution of prefabricated houses may be uneven (such as reduced stiffness in some areas due to loose splicing), further amplifying the local concentration effect of seismic forces and reducing the seismic performance of the structure.
