Seismic Effect of Prefabricated Panel Houses

The seismic performance of prefabricated panel houses is relatively poor. The main reasons can be analyzed from three aspects: structural characteristics, seismic capacity levels, and disaster response performance:

Poor overall structural integrity due to structural characteristics
Prefabricated panel houses adopt a spliced structure. The floor panels are pre-fabricated and then directly placed on the load-bearing walls, with mechanical lap joints or simple anchoring as the connection method between the floor panels and the walls. This connection method has significant drawbacks compared to cast-in-place structures. Cast-in-place structures form a continuous load-bearing system through the integral pouring of reinforced concrete, while the spliced joints in prefabricated panel structures are prone to becoming stress concentration points, leading to joint failure first during earthquakes. For example, under horizontal seismic forces, relative displacement may occur between the floor panels and the walls due to loose connections, ultimately causing the entire structure to collapse like a "jigsaw puzzle" and lose stability.

Generational differences in seismic capacity levels
The seismic capacity of prefabricated panel houses is closely related to their construction era. Old prefabricated panel houses built before the 1980s generally have a low design standard and can only withstand earthquakes of magnitude 6 (equivalent to about magnitude 5.0 on the Richter scale). Although newly built prefabricated panel houses use improved processes and have their seismic capacity increased to magnitude 7 (about magnitude 5.5-6.0 on the Richter scale), they are still significantly lower than that of cast-in-place reinforced concrete structures. Cast-in-place structures can form a stronger lateral force-resisting system through the coordinated work of the steel reinforcement framework and concrete, and usually can meet seismic fortification requirements of magnitude 8 or even higher.

Obvious shortcomings in disaster response performance
In natural disasters such as earthquakes and mudslides, the vulnerability of prefabricated panel houses is particularly prominent. The back-and-forth action of seismic waves accelerates the fatigue damage of the spliced joints. Even earthquakes that do not reach the designed seismic level may cause crack propagation due to the accumulation of micro-seisms. For example, multiple small earthquakes may cause tiny cracks to appear at the connections between the floor panels and the walls. Over time, the expansion of these cracks weakens the overall structural integrity, ultimately leading to partial or complete collapse. In addition, although the lightweight nature of prefabricated panel houses is beneficial for construction, it can exacerbate the damage in strong earthquakes due to excessive inertial forces.

Improvement suggestions
For existing prefabricated panel houses, reinforcement measures such as adding structural columns and ring beams can be taken to improve overall structural integrity. For newly built houses, it is recommended to give priority to cast-in-place structures or prefabricated concrete structures to enhance seismic performance.