T-shaped Bearing Beams in Prefabricated Houses

The T-shaped bearing beams in prefabricated houses mainly include two types: prefabricated T-beams and T-section prefabricated small beams in small-beam and thin-slab structures, with significant differences in their design, application, and renovation directions.

I. Prefabricated T-beams: The Mainstream Load-bearing Structure in Bridge Engineering

Prefabricated T-beams are widely used as upper load-bearing components in bridge engineering. Their structure consists of flanges on both sides and a central web, fabricated using reinforced concrete or prestressed technology. Key advantages include:

1. Superior Structural Performance: Leveraging the compressive strength of concrete and the tensile strength of steel, prestressed technology reduces cracks and enhances load-bearing and spanning capacities. The typical single-span length ranges from 30 to 40 meters, with a maximum of 50 meters, suitable for medium to large bridges.
2. High Construction Efficiency: Factory prefabrication and on-site assembly reduce on-site work time. Smart beam yard technology further shortens production cycles and improves quality stability through automated formwork and steam curing.
3. Cost-effectiveness: High material utilization results in lower costs compared to complex structures like box girders, with convenient transportation and installation reducing overall expenses.
   Typical applications include projects like the Qinmai Expressway and Luolu Expressway. The construction process involves steel reinforcement, formwork installation, concrete pouring, curing, and prestressed tensioning, requiring strict control of tensioning sequence and concrete strength to ensure structural safety.

II. T-section Prefabricated Small Beams: A Limited Structure in Historical Buildings

After the 1950s, small-beam and thin-slab structures were widely adopted in old urban areas of Shanghai, characterized by:

1. Simple Construction: T-shaped small beams with a span of about 3 meters paired with 35-45 mm thick slabs offer convenient construction and material savings.
2. Poor Durability: Due to low concrete strength and thin steel reinforcement cover, long-term use leads to issues like steel corrosion, slab cracking, and deformation. For example, the Baotun Road 211 Lane community required renovation to enhance safety due to structural aging.
   Renovation Directions:

• Demolition and Reconstruction: Complete demolition of severely damaged buildings and construction of new residences meeting modern standards.
• Reinforcement and Renovation: Techniques like steel beam replacement and carbon fiber cloth reinforcement extend structural lifespan. Shanghai plans to complete the renovation of most existing buildings of this type by 2025.

III. Summary and Comparison

Prefabricated T-beams are the preferred choice for modern bridge engineering due to their high performance and efficiency, while T-section prefabricated small beams are gradually phasing out of the mainstream market due to historical limitations. Key differences lie in the former's structural optimization through prestressed technology and industrialized production, while the latter requires renovation to address safety hazards due to material and process constraints. In the future, with advancements in construction technology, prefabricated load-bearing structures will place greater emphasis on durability, intelligence, and sustainability.