A Lead Rubber Bearing (LRB), also known as a lead-core rubber bearing, is a premium base isolation device engineered to protect bridges and buildings from earthquakes. Its robust construction features a central, cylindrical lead core press-fitted within a laminated stack of elastomeric rubber layers and reinforcing steel plates, all vulcanized into a single, high-performance unit. The lead core delivers exceptional energy dissipation through hysteretic damping, achieving an equivalent viscous damping ratio of up to 30%, while the rubber and steel layers provide flexible support, lengthening the structure's natural period to reduce seismic force impact. This synergy offers superior vertical load capacity, horizontal flexibility, and outstanding corrosion resistance. Available in round and rectangular shapes with single or multiple lead core options, our LRBs are custom-engineered to meet specific project demands for ultimate resilience and safety.
Top and bottom plates: transfer loading and constraint deformation of lead core.
Lead plug: dissipate energy and decrease displacement.
Steel reinforcing plates: increase vertical stiffness and constraint deformation of lead core.
Internal rubber layers: support structure weight, accommodate rotation and displacement, recovery moving bearing to the original position.
Rubber cover: protect reinforced steel plates and rubber layers.
Shear modulus: 0.8 MPa, 1.0 MPa, 1.2 MPa.
Working temperature range: -25 °C to +60 °C.
Lead core quantity: single or multiple.
Shape: rectangular and round.
Rectangular lead rubber bearing specifications.
Round lead rubber bearing specifications.
Table 1: Physical Properties of Rubber Materials
No | Test Item | Technology Requirement | Unit | |
1 | Hardness (Shore A) | 60±5 | HD | |
2 | Tensile Strength | ≥ 18 | MPa | |
3 | Elongation At Break | ≥ 550 | % | |
4 | Compression Set | 709 °C × 24 H | ≤ 30 | % |
5 | Brittleness Temperature | ≤ -50 | °C | |
6 | Ozone Aging(50 PPHM, 20% Elongation, 40 °C × 48 H) | No Creak | – | |
7 | Air Aging | Hardness Change (Shore A) | ≤ +6 | HD |
Tensile Strength Chang Rate | ≤ 12 | % | ||
- | Elongation At Break Chang Rate | ≤ 20 | % | |
Steel plates
Reinforcing plates, the top and bottom plates are made from rolled carbon steel conforming to EN10025, EN10083, and EN10088/SHTOA36 or A570.
Lead core
Lead with a minimum purity of 99.9%, which ensured the LRB have a good quality.
Lead Rubber Bearings (LRBs) operate on a sophisticated dual-mechanism principle to safeguard structures during seismic events: Flexible Period Shift and High-Energy Dissipation.
Flexible Period Shift & Decoupling: Similar to a standard laminated rubber bearing, the LRB's elastomeric layers provide high horizontal flexibility. During an earthquake, this allows the superstructure (the building or bridge deck above) to move slowly and laterally relative to the substructure (the foundation or pier below). This motion effectively decouples the structure from the high-frequency components of the ground shaking, significantly increasing the natural vibration period of the structure and reducing the seismic forces transmitted upwards.
High-Energy Dissipation (Damping): This is the critical enhancement provided by the central lead core. As the bearing deforms in shear, the lead core is forced to yield plastically. This plastic deformation of the lead absorbs a massive amount of seismic energy, converting it into heat. This process, known as hysteretic damping, can achieve an equivalent viscous damping ratio of up to 30%, dramatically dampening the structural response and minimizing displacement.
Self-Centering: Following the earthquake, the inherent elasticity of the laminated rubber bearing provides a restoring force, while the dynamic recovery of the lead core assists in guiding the structure back toward its original position, minimizing residual displacements.
Load Transfer Mechanism:
Vertical Load Path: Effectively supports gravity loads from the superstructure (e.g., beam → top connection plates → laminated rubber and steel layers → bottom connection plates → pier).
Horizontal Load Path: Manages seismic forces through the shear deformation of the rubber and the yielding of the lead core, with loads transferred through the connection plates and anchor bolts (e.g., from the pier upwards through the bearing components).
Our Lead Rubber Bearings are engineered to meet and exceed the most stringent international seismic codes. Core design adherence includes:
• European Standard (EN): EN 15129 (Anti-seismic devices)
• American Standard (AASHTO): AASHTO Guide Specifications for Seismic Isolation Design
We also design to accommodate other major national standards upon request, ensuring global project suitability and compliance.
While ordinary elastomeric bearings provide basic flexibility, Lead Rubber Bearings (LRBs) deliver advanced seismic protection through active energy dissipation. The performance gap is critical, especially for projects in high-seismic zones. The core difference lies not just in the damping coefficient (ordinary bearings: <5% vs. LRBs: >15%), but in their overall seismic response strategy.
The following comparison highlights the key advantages of LRB seismic bearings:
Performance Metric | Ordinary Rubber Bearing | Lead Rubber Bearing (LRB) | Benefit for Your Structure |
Damping Performance & Energy Dissipation | Low; relies solely on inherent rubber properties. | High; the lead core yields plastically, actively absorbing seismic energy. | Dramatically reduces forces and accelerations transferred to the superstructure, protecting critical elements. |
Self-Centering Capability | Weaker; may lead to significant residual displacements. | Strong; the elasticity of the laminated rubber provides excellent restoring force. | Minimizes post-earthquake damage and repair costs, facilitating a quicker return to service. |
Maximum Shear Displacement | Limited by the rubber material alone. | Enhanced stability allows for larger, safer displacements. | Provides a greater margin of safety during extreme seismic events. |
This superior performance makes LRB bridge bearings and LRB building bearings the ideal choice for regions with high seismic intensity (Zone 8 and above). By significantly improving the structure's stress state during an earthquake, LRBs transform from a simple component into a critical seismic safety system. They are essential for ensuring the structural integrity and post-earthquake functionality of bridges, hospitals, and other vital infrastructure.
Our Lead Rubber Bearing design and manufacturing process strictly adhere to international standards, including EN 15129 and AASHTO guidelines, guaranteeing global compliance and proven reliability.
Precision Manufacturing Process & Rigorous Quality Assurance
Our Lead Rubber Bearings are manufactured through a meticulously controlled process that ensures superior performance and longevity:
1. Lamination and Pre-forming: The elastomeric rubber layers and reinforcing steel plates are precisely laminated and vulcanized into a single, unified bearing body, with a pre-reserved cavity for the lead core.
2. Lead Core Integration: The high-purity lead core is hydraulically pressed into the cavity. The entire unit is then secondarily vulcanized, creating a permanent, monolithic structure that guarantees optimal energy dissipation.
3.Sealing and Connection: Top and bottom sealing plates are vulcanized onto the bearing, providing superior corrosion protection. The final connection plates are then assembled, ready for site anchoring.
4.Final Inspection and Packaging: Each bearing undergoes a final inspection before being carefully packaged with protective films to prevent damage during shipping and storage.
Uncompromising Quality Control
Our commitment to quality is embedded in every step. We adhere strictly to EN 15129 and AASHTO standards. Our in-house laboratory, equipped with shear testers, ozone resistance testers, and aging ovens, allows us to validate the performance and durability of every batch, ensuring consistent and reliable quality for all projects.
Application
Lead rubber bearing, main branch of seismic isolation system, is widely applied to the large sized structures such as road bridges, rail bridges and nuclear power station to minimize damages from dynamic loads like earthquake.
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Westcoast New Area, Qingdao City ,Shandong Province ,China
