Natural Rubber Bearing(NRB) – Seismic Isolation for Bridges

Natural Rubber Bearings (NRB) are high-performance seismic isolation devices composed of multiple layers of natural rubber bonded with reinforced steel plates. These bearings provide excellent vertical load-bearing capacity and large horizontal flexibility, making them ideal for bridges, residential and commercial buildings, hospitals, and infrastructure requiring seismic isolation. Although NRBs have lower energy dissipation compared to high damping bearings, they are often used together with dampers to enhance performance, ensuring structural safety, reducing vibration transmission, and extending service life.

Structure of Natural Rubber Bearings

Natural Rubber Bearings are constructed with top and bottom steel connecting plates, internal steel laminates, natural rubber layers, and a protective rubber cover. The steel plates significantly constrain vertical compression deformation, enabling the bearings to withstand high vertical loads. Meanwhile, the rubber layers allow significant horizontal shear deformation, making NRBs effective in accommodating structural displacements caused by temperature changes, wind loads, or earthquakes.

Working Principle of Natural Rubber Bearings

Installed between the superstructure and foundation, NRBs form a seismic isolation layer that converts strong ground vibrations into slow horizontal movements. This mechanism prolongs the natural vibration period of the structure, reducing seismic energy transfer to the upper structure. After an earthquake or wind-induced vibration, the bearings quickly restore to their original position due to the rubber’s stable restoring force.

Features of Natural Rubber Bearings

• High vertical load capacity and stable structural support
• Large horizontal deformation capacity to accommodate seismic displacement
• Extends the vibration period of structures, reducing seismic energy input
• Strong adhesion between rubber and steel for durability under repeated stress
• Excellent linearity and stable restoring force for quick recovery post-earthquake
• Maintenance-free, long service life, and easy installation
• Compatible with various dampers for improved energy dissipation
• Cost-effective solution for seismic isolation in low-to-moderate seismic zones

Applications of Natural Rubber Bearings

• Bridges: Highway bridges, railway bridges, and viaducts
• Buildings: Residential, office, and hospital structures requiring vibration isolation
• Industrial Structures: Antivibration mountings for equipment and underground rail systems
• Foundations: Earthquake protection for low-seismic-risk regions

Common Specifications of Natural Rubber Bearings

Vertical Load Capacity

• Ranges from 500 kN to 20,000 kN based on design requirements

Horizontal Displacement Capacity

• Standard shear strain: up to 150%
• Suitable for small-to-medium horizontal displacements

Working Temperature

• -25°C to +60°C for standard natural rubber bearings

Common Sizes (Length × Width × Thickness)

• 200 × 300 × 50 mm
• 300 × 400 × 60 mm
• 400 × 500 × 80 mm
• 500 × 600 × 100 mm
  (Custom sizes available as per project requirements)

Rubber Elastic Modulus Options

• G0.30, G0.35, G0.40, and G0.45, suitable for different load conditions

Why Choose Aohong Natural Rubber Bearings?

Aohong’s Natural Rubber Bearings are designed and manufactured to meet international standards, offering superior performance in vertical load transfer, horizontal flexibility, and vibration isolation. With customizable sizes and advanced production technology, Aohong ensures reliable, durable, and cost-effective solutions for bridges and buildings worldwide.

Specification