Seismic Resistance of Prefabricated Hollow Slab Houses

The seismic performance of prefabricated hollow slab houses varies significantly depending on the age of the house, structural type, and reinforcement measures. Overall, their seismic resistance is generally lower than that of cast-in-place reinforced concrete houses, but safety can be enhanced through targeted measures.

I. Seismic Capacity of Prefabricated Hollow Slab Houses from Different Eras

1. Old prefabricated slab houses built before the 1980s: Limited by the design standards of the time, their seismic capacity is relatively weak, typically able to withstand only a magnitude 6 earthquake. These houses often adopt a brick-concrete structure, with simple connection methods between the prefabricated slabs and walls, resulting in poor overall integrity. During earthquakes, they are prone to slab detachment or wall collapse due to connection failure.
2. Newly built prefabricated slab houses: With updated specifications, the seismic capacity of newly built prefabricated slab houses has been increased to magnitude 7, but their overall integrity remains insufficient. Their structure relies heavily on the assembly of prefabricated components, with node connection strength lower than that of cast-in-place structures, making them prone to component misalignment or disintegration during earthquakes.

II. Key Factors Affecting Seismic Performance

1. Building height and structural type:
   • Prefabricated hollow slab houses with a height of six stories or less are relatively safe, while high-rise buildings face significantly increased seismic risks due to their high center of gravity and large horizontal loads.
   • Frame structures are superior to brick-concrete structures: Frame structures form an overall load-bearing system through beams and columns, offering stronger seismic performance; brick-concrete structures rely on walls for load-bearing, with weak connections between prefabricated slabs and walls, making them a seismic vulnerability.
2. Foundation treatment:
   • Deep excavation or pile foundations can enhance house stability, reducing structural damage caused by foundation settlement or tilting during earthquakes.
3. Type of prefabricated slab:
   • Prefabricated prestressed hollow slabs, due to the effect of prestressing, offer better crack resistance and overall integrity than ordinary prefabricated slabs. However, construction quality must be ensured (e.g., welding of steel bar joints, crack repair), otherwise, performance will significantly decline.

III. Reinforcement Measures to Improve Seismic Performance

1. Structural reinforcement:
   • Install steel frames or pour concrete inside walls to enhance the connection strength between walls and prefabricated slabs;
   • Lay steel mesh and pour fine aggregate concrete at joints to improve node shear resistance.
2. Seismic isolation technology:
   • Install seismic isolation bearings to reduce earthquake energy input by extending the structure's natural vibration period, suitable for low- to medium-rise buildings.
3. Material upgrades:
   • Use high-ductility cement-based composites (ECC) to repair cracks, enhancing component deformation capacity;
   • Reinforce prefabricated slabs with carbon fiber sheets to increase flexural bearing capacity.

Summary: The seismic performance of prefabricated hollow slab houses must be comprehensively evaluated based on factors such as age, structure, and foundation. For old houses, it is recommended to develop reinforcement plans through professional inspections, while new houses should prioritize frame structures and strictly control construction quality to minimize earthquake risks.