Laminated rubber bearings are widely used in bridges and building structures to transfer loads, accommodate movement, and reduce vibration. Their durability is essential for long service life, structural safety, and cost-effective maintenance. Several factors influence their performance over time.
Material Quality
- Rubber Composition: Natural rubber (NR) and chloroprene rubber (CR/neoprene) have different resistance to weathering, ozone, and temperature. High-quality compounds improve aging resistance.
- Steel Lamination: The thickness, grade, and corrosion protection of embedded steel plates directly affect strength and fatigue life.
Environmental Conditions
- Temperature Extremes: Prolonged exposure to very high or low temperatures can cause hardening, softening, or cracking of rubber.
- Ozone and UV Radiation: Outdoor exposure can degrade surface layers if bearings lack protective coatings.
- Moisture and Chemicals: Saltwater, de-icing agents, and industrial pollutants accelerate material degradation.
Structural and Load Conditions
- Vertical Loads: Bearings must be designed for the expected maximum service load without excessive compression set.
- Horizontal Movement: Large shear strains or repeated displacement cycles increase wear and fatigue.
- Rotation: Excessive rotation beyond design limits can cause edge damage and delamination.
Manufacturing Standards and Quality Control
- Compliance with AASHTO, EN 1337-3, BS 5400, and ISO 22762 ensures that material properties, dimensions, and tolerances meet safety requirements.
- Rigorous factory testing, including compression, shear modulus, and aging tests, helps prevent early failure.
Maintenance and Inspection
- Regular inspections detect signs of cracking, bulging, corrosion, or deformation.
- Timely cleaning and re-coating of exposed steel parts help extend lifespan.