Analysis of the Structure of Prefabricated Slab Houses

Prefabricated slab houses are primarily constructed with brick-concrete structures, characterized by fixed structural forms, compact spaces, and limited flexibility for renovation. Their design life is typically 50 years, with actual service life influenced by various factors.

Structural Characteristics

1. Structural Form: Prefabricated slab houses mainly adopt brick-concrete structures, with floors made of prefabricated concrete slabs and walls mostly consisting of load-bearing brick walls, resulting in relatively low overall stiffness. This structure relies on the load-bearing capacity of the walls, with floors connected to load-bearing walls through prefabricated slabs to form an integrated structure.
2. Floor Plan Layout: Due to the size limitations of prefabricated slabs, the design of house types is relatively fixed, with small room spans (generally 3-4 meters) and poor north-south ventilation. This layout leads to low space utilization efficiency and difficulty in meeting modern residential demands for flexibility.
3. Floor Height and Span: The floor height is usually low (2.6-2.8 meters), and the spatial layout is compact due to the span limitations of prefabricated slabs. While this design met basic residential needs in the early days, its limitations have become increasingly apparent as modern residential demands for spatial comfort have risen.
4. Load-Bearing Method: The walls are mostly load-bearing, with floors connected to load-bearing walls through prefabricated slabs. The overall structure relies on the load-bearing capacity of the walls, resulting in limited flexibility for renovation and difficulty in making large-scale structural adjustments.

Types of Prefabricated Slabs

1. Solid Slabs: These are made by pouring concrete throughout and are suitable for areas requiring high structural strength, such as connections to load-bearing walls or key load-bearing nodes.
2. Hollow Slabs: The hollow sections do not bear loads, and pouring concrete into them serves no practical purpose. Therefore, these sections are left hollow to reduce weight and save on construction costs. However, the use of prefabricated hollow slabs is no longer recommended. Modern building structures mostly adopt cast-in-place structures, which offer better integrity and superior seismic performance.

Design Life and Actual Service Life

1. Design Life: According to the Unified Standard for Reliability Design of Building Structures (GB 50068-2018), the design service life of prefabricated slab buildings as ordinary residences is typically 50 years.
2. Actual Service Life: This is influenced by various factors, including construction quality, usage and maintenance conditions, policies and urban planning, and socio-economic factors. For example, early prefabricated slab buildings may have construction defects, such as loose component connections and insufficient concrete strength. In terms of material aging, concrete exposed to the environment for a long time may undergo carbonation, leading to steel corrosion and a reduction in structural strength. Additionally, early seismic design standards were relatively low and may not meet modern seismic requirements, especially in earthquake-prone areas.