Basin type rubber support GPZ1000GD

Pot bearings are advanced structural components engineered for heavy-load, large-displacement scenarios in infrastructure projects. Unlike traditional rubber bearings, they excel in supporting ultra-large vertical loads (ranging from 1,000 kN to 50,000 kN) and accommodating multi-directional displacements, making them indispensable for high-speed railways, long-span bridges, and mega-buildings. Compliant with international standards such as GB/T 17955, EN 1337-5, and AASHTO LRFD Bridge Design Specifications, they ensure long-term structural safety under dynamic and harsh conditions.

1. Core Structure: Material & Technical Details

Pot bearings feature a modular, high-strength design with four key components, each optimized for performance:

1.1 Cast Steel Basin (Load-Bearing Core)

Material: High-tensile cast steel (e.g., Q345B, Q460C) or alloy steel, with a minimum yield strength of 345 MPa.

Function: Acts as the primary load carrier, distributing vertical loads (from bridge girders, building slabs) evenly to the foundation. Its bowl-shaped structure also restricts excessive lateral movement, preventing bearing disengagement during earthquakes.

Design Features: Thickened bottom (15–30 mm) for impact resistance; anti-corrosion treatment (hot-dip galvanization, epoxy coating, or fluorocarbon painting) to withstand salt spray (for coastal projects) or industrial fumes.

1.2 PTFE (Polytetrafluoroethylene) Slide Plate

Material: Modified PTFE composite (blended with glass fiber or bronze powder) for enhanced wear resistance.

Key Parameters:

Coefficient of friction: ≤ 0.03 (dry condition) or ≤ 0.015 (with silicone grease lubrication).

Operating temperature range: -40℃ to 80℃ (special formulations for -60℃ cold regions available).

Thickness: 5–10 mm, with a surface flatness tolerance of ≤ 0.1 mm/m.

Function: Enables smooth horizontal displacement (±50 mm to ±300 mm) and small-angle rotation (0.02–0.05 rad) caused by temperature changes, concrete creep, or vehicle vibrations—avoiding rigid structural stress.

1.3 Sealing & Cushion Assemblies

Sealing Ring: Made of nitrile rubber (NBR) or EPDM, with a Shore hardness of 60±5. It prevents dust, water, and corrosive media from entering the gap between the basin and slide plate, prolonging PTFE service life.

Elastic Cushion: Optional natural rubber or high-damping rubber pad (placed between the basin and upper structure) for secondary vibration absorption—reducing noise and impact from high-speed trains or heavy equipment by 15–25 dB.

1.4 Guide/Anchor Devices (Optional)

For bridges with high lateral loads (e.g., mountainous highways, curved rail lines), additional steel guides or anchor bolts are integrated. These restrict displacement to a single direction (e.g., longitudinal) or fix the bearing in place, preventing lateral slippage.

2. Core Functional Principles

Pot bearings achieve their performance through three synergistic mechanisms:

2.1 Load Transfer Mechanism

Vertical loads are first applied to the upper sliding plate, then distributed to the cast steel basin. The basin’s curved inner wall converts partial vertical force into radial pressure, ensuring the load is evenly transmitted to the foundation—avoiding local stress concentrations (a common cause of concrete foundation cracking).

2.2 Displacement Adaptation Mechanism

Horizontal Displacement: The low-friction PTFE plate slides against the stainless steel upper surface (attached to the structure), allowing controlled movement without mechanical jamming.

Rotation Compensation: The flexible contact between the PTFE plate and basin’s inner edge accommodates small-angle rotations (e.g., due to bridge girder deflection under load), maintaining full contact and load stability.

2.3 Durability & Safety Mechanisms

Corrosion Resistance: Galvanized/coated steel and EPDM seals resist rust in coastal (saltwater) or industrial (acidic fumes) environments—tested to withstand 1,000 hours of neutral salt spray without visible corrosion.

Seismic Protection: In earthquake-prone zones, "seismic pot bearings" integrate shear keys (made of high-strength steel) that absorb horizontal seismic forces. If the force exceeds the design limit, the shear keys yield gradually, preventing catastrophic bearing failure.

3. Typical Applications & Project Cases

Pot bearings are tailored to diverse engineering needs, with proven performance in landmark projects:

3.1 High-Speed Rail (HSR) & Railway Bridges

Use Case: Supporting HSR box girders (e.g., China’s Fuxing EMU lines), where bearings must withstand frequent dynamic loads (30–50 Hz vibration) and temperature-induced displacements (up to ±150 mm in seasonal changes).

Case Example: Beijing-Shanghai High-Speed Railway—adopted pot bearings with 5,000 kN vertical load capacity, PTFE slide plates, and EPDM seals. Operating for 12+ years with zero maintenance-related failures.

3.2 Cross-River/Sea Bridges

Use Case: Withstanding saltwater corrosion, strong winds, and tidal forces. Bearings here require enhanced anti-corrosion (fluorocarbon coating) and large displacement capacity.

Case Example: Hong Kong-Zhuhai-Macao Bridge—used pot bearings with 10,000 kN load capacity, 316L stainless steel sliding surfaces, and NBR seals. Designed to resist 12-level typhoons and 50 years of saltwater exposure.

3.3 Large-Span Buildings

Use Case: Supporting steel trusses or concrete slabs in stadiums, airports, or exhibition centers—where bearings must adapt to structural deflection (e.g., stadium roof deformation under snow load).

Case Example: Beijing National Stadium ("Bird’s Nest")—installed pot bearings with 8,000 kN capacity and rotation tolerance of 0.04 rad, accommodating roof deflection of up to 200 mm.

3.4 Heavy-Industry Facilities

Use Case: Supporting heavy equipment (e.g., 1,000-ton forging presses, large generators) in factories. Bearings here need ultra-high load capacity and minimal displacement.

Case Example: Shanghai Baosteel Heavy Machinery Plant—used pot bearings with 20,000 kN vertical load capacity, fixed anchor devices, and wear-resistant PTFE plates.

4. Key Advantages Over Alternative Bearings

Compared to rubber bearings or spherical bearings, pot bearings offer unique benefits:

Feature

Pot Bearings

Rubber Bearings

Load Capacity

1,000–50,000 kN (ultra-large loads)

Up to 5,000 kN

Displacement Range

±50–±300 mm (multi-directional)

±20–±100 mm (limited)

Service Life

50+ years (design life)

20–30 years

Maintenance Needs

Low (inspect every 5 years)

Frequent (replace rubber every 10–15 years)

Harsh Environment Adaptability

Excellent (corrosion, cold, vibration)

Poor (aging in UV/saltwater)

5. Installation & Maintenance Guidelines

Proper installation and maintenance are critical to maximizing pot bearing lifespan:

5.1 Installation Requirements

Leveling: The foundation must be leveled to within ±0.5 mm/m to avoid uneven load distribution.

Lubrication: Apply silicone grease (compatible with PTFE) to the slide plate before installation—ensuring friction coefficient ≤ 0.02.

Alignment: For guided bearings, ensure the guide direction matches the structure’s intended displacement (e.g., longitudinal for bridges).

5.2 Routine Maintenance

Inspection Frequency: Annually for general projects; semi-annually for coastal/HSR projects.

Key Checks:

Sealing ring integrity (no cracks or deformation).

PTFE plate wear (replace if thickness < 3 mm).

Lubrication status (reapply grease if dry).

Repair: Minor wear can be addressed by replacing the PTFE plate; severe corrosion or structural damage requires full bearing replacement.