What are the functions of plate rubber bearings for highway bridges
Plate rubber bearings for highway bridges are important connecting components in bridge structures, mainly composed of rubber materials and thin steel plates alternately laminated and vulcanized. With their elastic deformation and structural characteristics, they play various key roles in bridge engineering, as follows:
Plate rubber bearings for highway bridges are important connecting components in bridge structures, mainly composed of rubber materials and thin steel plates alternately laminated and vulcanized. With their elastic deformation and structural characteristics, they play various key roles in bridge engineering, as follows:
1、 Support and transmission function
Load bearing upper structure: directly bear the self weight of the upper structure of the bridge (such as beams, bridge deck systems) and live loads of vehicles, pedestrians, etc., and evenly transfer the load to the lower structure (piers, abutments, pile foundations) to ensure the overall force balance of the bridge.
Disperse local stress: The elasticity of rubber materials can buffer the impact of loads on piers and abutments, avoiding local stress concentration that can cause concrete cracking. At the same time, the compressive stiffness of the support is enhanced by steel plates to ensure the reliability of load transmission.
2、 Adapt to deformation requirements
1. Displacement adaptation
Horizontal displacement compensation: When the bridge experiences horizontal displacement due to temperature changes, concrete shrinkage and creep, or vehicle braking force, the rubber bearings absorb the displacement through shear deformation (lateral displacement of the rubber layer), allowing the beam to move freely in the longitudinal or transverse direction of the bridge, avoiding additional internal forces caused by structural displacement obstruction.
Corner adaptation: When the beam is bent and produces a corner (such as when the beam end tilts upwards under mid span load), the upper surface of the support forms a small inclination angle with the beam bottom, and the lower surface forms a small inclination angle with the top surface of the pier. The elastic compression and shear deformation of the rubber can adapt to this corner (usually allowing a corner of ≤ 0.02rad), ensuring the freedom of rotation of the beam.
2. Deformation buffering
When the vehicle passes by, the support absorbs the vertical vibration of the beam through the elastic deformation of the rubber, reduces the bumpy bridge surface, improves driving comfort, and reduces fatigue damage to the bridge structure caused by vibration.
3、 Structural protection and durability improvement
Isolation of vibration and impact: The elasticity of rubber can isolate the vibration transmission between the lower structure (such as piers and abutments) and the upper beam, especially under earthquake, wind load or vehicle impact, reducing the risk of structural resonance through energy dissipation and improving the seismic performance of bridges.
Prevent rigid contact wear: Avoid wear and noise caused by direct rigid contact between the beam and the pier, and extend the service life of various components of the bridge.
4、 Simplify construction and maintenance
Convenience of installation: Plate rubber bearings have a simple structure (usually rectangular or circular) and do not require complex anchoring devices. They can be directly laid on the top surface of the pier and abutment, and fixed by the self weight of the beam, reducing construction difficulty and cost.
Low maintenance cost: Rubber materials have good aging resistance (normal service life of 20-30 years), and do not require frequent lubrication or adjustment. Only regular inspections are needed to check for aging, cracking, or delamination issues, making maintenance convenient.
5、 Typical application scenarios
Small and medium span bridges: suitable for simply supported beam bridges and continuous beam bridges with a span of ≤ 30m, such as urban road bridges, rural road bridges, etc. It is currently one of the most widely used types of bearings in highway bridges.
Regions with large temperature differences: The elastic deformation of rubber is used to adapt to the expansion and contraction of the beam caused by temperature changes, reducing the impact of temperature stress on the structure.