Technical Essentials for Joint-Free Super-Long Cold Storage Structures: Achieving a 120m Integrated Solution

Technical Essentials for Joint-Free Super-Long Cold Storage Structures: Achieving a 120m Integrated Solution

I. Origin and Cost of Expansion Joints

Buildings experience internal stresses due to temperature changes, concrete shrinkage, and uneven foundation settlement. When a building exceeds a certain length, accumulated stresses may cause cracking. Traditional practice involves setting expansion joints—dividing the building into independent units that deform freely, with double walls and columns at the joints. For ordinary buildings, expansion joints are reasonable and economical. However, for cold storage, the comprehensive costs are high:

• Structural cost of double walls and columns: Each expansion joint requires two parallel structural walls and double columns, increasing construction costs and creating functional separation between adjacent storage areas.
• Energy cost of double-layer insulation: Double walls at joints mean double-layer insulation walls, with prominent thermal bridges increasing energy consumption and construction difficulty.
• Operational fragmentation: Storage areas separated by joints are treated as independent units for cargo handling, temperature management, and fire zoning, limiting operational flexibility.

Where conditions permit, eliminating expansion joints through active structural techniques positively impacts the life-cycle economy of cold storage. The Taiku system achieves joint-free integrated structural design within a 120m building length, systematically addressing these issues.

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II. Technical Prerequisites for Joint-Free Super-Long Structures

Eliminating expansion joints is not simply "not setting joints" but actively transforming stresses that would otherwise be released through joints into a safe load-bearing state. Achieving this requires the following technical prerequisites:

Active Prestress Compensation

Concrete shrinkage is the primary cause of tensile stress in super-long structures. Prestressing applies compressive stress to concrete in advance. When shrinkage occurs, tensile stress must first overcome this initial compression before causing cracking. Properly designed prestress can cover normal shrinkage-induced tensile stress, keeping concrete in compression or slight tension throughout its life, fundamentally reducing cracking conditions.

Refined Thermal Stress Analysis

Cold storage experiences extreme temperature differences: interior as low as -30°C or lower, exterior exposed to ambient conditions. This temperature gradient induces stress within structural sections, requiring specialized calculation. In the Taiku system, thermal and shrinkage stresses are analyzed together and covered in prestress design, ensuring stress remains safe under worst-case thermal conditions.

Low-Shrinkage Concrete Mix Control

Beyond structural design, material-level shrinkage control is crucial. Optimizing water-cement ratio, selecting low-shrinkage cement, and incorporating appropriate expansion agents reduce concrete shrinkage at the source, easing the compensation burden on the prestressing system and providing a more reliable foundation for joint-free design.

Construction-Stage Stress Management

The construction phase is the most concentrated period for stress development in super-long structures. Early shrinkage rates after concrete placement are much higher than long-term rates. Improper management can cause early cracking before prestress tensioning. The Taiku system specifies key control points such as concrete placement segments, curing time, and tensioning schedule to ensure stress development remains controllable.

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III. Economic Benefits of Merging Two Warehouses into One

The direct application of 120m joint-free design is merging two 50–60m independent cold storage units into one 120m integrated facility. The combined economic benefits are as follows:

Cost Item	Two Separate Warehouses (with Joints)	Integrated (Joint-Free)	Savings
Double walls and columns at joint	Present	Eliminated	Significant reduction
Insulation system	Double-layer insulation walls	Single-layer insulation walls	~20% reduction in insulation area
Fire zoning	Two independent zones	Can be merged into one large zone	Simplified fire protection
Operational management	Two independent management units	One integrated unit	Improved operational efficiency
Long-term operational energy	More thermal bridges, higher energy consumption	Fewer thermal bridges, lower energy consumption	~15% reduction (subject to confirmation)

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IV. Applicability

The Taiku joint-free super-long design is suitable under the following conditions:

• Single cold storage building length between 60–120m
• Uniform site geology with no significant differential settlement risk
• Use of large-span prestressed flat slabs as floor system
• Concrete construction quality control meeting code requirements

For cold storage exceeding 120m, a case-specific analysis is needed to assess the suitability of joint-free or jointed design. The BICP technical team can provide recommendations based on project information.