Luhai Feng Phase III Cold Storage Project

The applicability of conventional post-tensioned anchorage systems under ultra-low temperature conditions was the primary technical challenge. While post-tensioning technology is well-established for normal and standard freezing temperatures (-18°C to -25°C), at -60°C material properties change significantly: ordinary carbon steel risks brittle fracture below its ductile-to-brittle transition temperature; sealing components (rubber-based materials) harden and shrink, reducing sealing performance; and the friction coefficient between tendons and anchors changes, affecting anchorage stability. Any instability in the anchorage system under ultra-low temperatures would directly compromise the long-term effective prestress in the floor slab, impacting crack resistance and structural safety.

Structural system: A large-span post-tensioned flat slab system was adopted to minimize internal columns, providing ample space for standard racking of national reserve goods. BICP-ST anchorage system: The anchor body uses a specialized alloy with verified low-temperature toughness, tested for mechanical properties at ultra-low temperatures to ensure no embrittlement risk and stable anchorage performance. Sealing components utilize elastomeric materials adapted for low-temperature shrinkage, combined with a secondary grouting seal design to maintain effective sealing under long-term operating temperatures. Low-temperature prestress design: Specialized calculations were performed for concrete thermal contraction and long-term prestress loss under -60°C conditions, incorporating low-temperature correction factors to ensure the effective prestress in the slab meets design requirements throughout its service life. Concrete mix design: Optimized for durability in ultra-low temperatures, enhancing freeze-thaw resistance. Construction phase: A specialized post-tensioning construction plan was developed for ultra-low temperature cold storage, including specific procedures for tensioning sequence, curing temperature control, and anchorage protection to ensure material performance and operations meet the unique requirements.

The Luhai Feng Phase III Cold Storage Project is located in the Northern China International Aquatic Products Trading Center and Cold Chain Logistics Base, positioned as a key component of the national backbone cold chain logistics base. It serves the storage of ultra-low temperature aquatic products (including deep-sea fish like tuna) and national meat reserves.

The internal operating temperature reaches as low as -60°C, which is the core constraint for structural design and material selection.

The applicability of conventional post-tensioned anchorage systems under ultra-low temperature conditions was the primary technical challenge.

While post-tensioning technology is well-established for normal and standard freezing temperatures (-18°C to -25°C), at -60°C material properties change significantly:

• Ordinary carbon steel risks brittle fracture below its ductile-to-brittle transition temperature.
• Sealing components (rubber-based materials) harden and shrink, reducing sealing performance.
• The friction coefficient between tendons and anchors changes, affecting anchorage stability.

Any instability in the anchorage system under ultra-low temperatures would directly compromise the long-term effective prestress in the floor slab, impacting crack resistance and structural safety.

Structural System: A large-span post-tensioned flat slab system was adopted to minimize internal columns, providing ample space for standard racking of national reserve goods.

BICP-ST Anchorage System:

• The anchor body uses a specialized alloy with verified low-temperature toughness, tested for mechanical properties at ultra-low temperatures to ensure no embrittlement risk and stable anchorage performance.
• Sealing components utilize elastomeric materials adapted for low-temperature shrinkage, combined with a secondary grouting seal design to maintain effective sealing under long-term operating temperatures.

Low-Temperature Prestress Design: Specialized calculations were performed for concrete thermal contraction and long-term prestress loss under -60°C conditions, incorporating low-temperature correction factors to ensure the effective prestress in the slab meets design requirements throughout its service life.

Concrete Mix Design: Optimized for durability in ultra-low temperatures, enhancing freeze-thaw resistance.

A specialized post-tensioning construction plan was developed for ultra-low temperature cold storage, including specific procedures for tensioning sequence, curing temperature control, and anchorage protection to ensure material performance and operations meet the unique requirements.

Post-completion, under the -60°C operating environment, the post-tensioned structure and BICP-ST anchorage system have maintained stable performance through subsequent periodic inspections. The large-span column layout effectively reduces internal columns, improving racking layout for national reserve goods and enhancing warehouse management efficiency.