BICP-ST Anchorage System Technical Note: Anchorage Performance at -70°C

Why Cold Storage Anchorage Is a Special Problem

Prestressed anchorage systems are critical to post-tensioned structures. If the anchorage fails during service, the prestressing force is lost. In ambient-temperature buildings, anchorage technology is mature and reliable. However, cold storage, especially at -30°C, -40°C, or even -60°C, introduces additional challenges: material properties change significantly, and assumptions for conventional systems no longer hold.

The BICP-ST anchorage system is specifically developed for these conditions, ensuring stable anchorage efficiency at -70°C without degradation.

Low-Temperature Effects on Anchorage Systems

Metal Embrittlement

Steel has a ductile-to-brittle transition temperature (DBTT). Below this point, material fractures suddenly without warning. For anchorage components, if DBTT is higher than the storage temperature, brittle fracture risk exists. Common carbon steel has DBTT between 0°C and -20°C, unsuitable for cold storage. Some alloy steels only guarantee toughness to -40°C. At -60°C to -70°C, specialized low-temperature steels or alloys are required.

Seal Hardening

Seals (e.g., rubber O-rings) harden and shrink at low temperatures, leading to leakage. Moisture or corrosive agents can then attack the anchorage and tendons, accelerating corrosion.

Friction Coefficient Variation

Friction between tendons and ducts changes with temperature. For unbonded tendons, the PE sheath's friction characteristics alter, affecting prestress loss estimation and stress distribution at the anchorage.

BICP-ST Technical Solution

Material Optimization

Anchorage components use specially selected low-temperature alloy steel with DBTT verified below -70°C via Charpy impact tests at -70°C, ensuring sufficient ductility and no brittle fracture risk.

Seal Design

Seals are made of low-temperature elastomers (e.g., special silicone or fluororubber) with glass transition temperature far below -70°C, maintaining elasticity and sealing integrity. An additional waterproof layer provides dual protection.

Long-Term Anchorage Efficiency Stability

Accelerated durability tests simulating actual cold storage conditions (constant low temperature plus cyclic temperature fluctuations) confirm that anchorage efficiency does not degrade substantially compared to ambient conditions. Test reports are available upon request.

Engineering Applications

BICP-ST has been validated in multiple low-temperature and ultra-low temperature cold storage projects, including:

• -60°C ultra-low temperature cold storage (Luhai Feng Phase III): Anchorage system performs stably in ultra-low temperature seafood storage environment, with periodic inspections confirming performance.
• -30°C to -25°C standard cold storage: Applied in over 300 cold storage projects across China, with good long-term performance.

Technical Support Services

Supply of BICP-ST includes:

• Low-temperature mechanical property test reports for anchorage materials
• Assistance with refined prestress loss calculations for low-temperature conditions
• On-site technical guidance for tensioning under low-temperature requirements
• Traceable quality records for each production batch

For owners and design firms with low-temperature cold storage needs, please contact BICP technical team for further discussion.