Rubber Bearing for Railway Engineering
Rubber bearings used in railway engineering are important components commonly employed in the construction of railway bridges. The following will introduce them in terms of their main types, characteristics, functions, and technical parameters:
Main Types
- Slab Rubber Bearings: These are composed of multiple layers of natural rubber inlaid, bonded, and vulcanized with thin steel plates.
- Pot Rubber Bearings: They are a type of pot rubber bearing product specifically designed and manufactured for railway beams, available in two forms: fixed type and movable type.
Characteristics
- Slab Rubber Bearings
- Simple Structure: The structure is relatively simple, mainly consisting of rubber and thin steel plates, without complex mechanical components or structures.
- Easy Installation: They are relatively light in weight and have a regular shape. The installation process is relatively easy, and there is no need for special large-scale equipment or complex installation techniques, which can effectively shorten the construction time.
- Low Cost: Compared with other types of bearings, the material cost and manufacturing cost are relatively low. While meeting the engineering requirements, it can reduce the overall cost of bridge construction.
- Convenient Maintenance: The daily maintenance work mainly involves regular inspection of the appearance and deformation of the bearings. There is no need for complex maintenance and repair operations, and the maintenance cost is low.
- Pot Rubber Bearings
- High Load-bearing Capacity: They can bear vertical loads ranging from 2500kN to 50000kN, which can meet the load-bearing requirements of railway bridges of different scales.
- Adapt to Large Displacements: The designed displacement can reach ±50mm to ±250mm, and it can adapt to the large horizontal displacements of the bridge caused by temperature changes and the action of train loads.
- Good Rotation Performance: The designed rotation angle is not less than 0.02rad, which can well adapt to the rotation of the bridge beam ends and ensure the stability of the bridge structure.
Functions
- Load Transfer: Reliably transfer the loads of the superstructure of the bridge, including its own weight, train loads, etc., to the piers, abutments, and foundations, ensuring the stability and safety of the bridge structure.
- Adapt to Deformations: Adapt to the horizontal displacements and beam end rotations of the bridge caused by various factors, such as the expansion and contraction deformations caused by temperature changes, and the vibrations and deformations generated by the running of trains, so that the bridge structure can work normally.
- Shock Absorption and Isolation: The rubber material has good elastic and damping properties, which can absorb and dissipate seismic energy as well as the vibration energy generated by the running of trains, reducing the vibration effects on the bridge structure and foundations and extending the service life of the bridge.
Technical Parameters
- Vertical Load-bearing Capacity: Slab rubber bearings have multiple levels of vertical load-bearing capacity according to different specifications; pot rubber bearings have 24 vertical load-bearing capacity levels, ranging from 2500kN to 50000kN. For special requirements, they can be separately designed when exceeding 50000kN.
- Applicable Temperature Range: Generally, there are two types: normal temperature type and cold-resistant type. The normal temperature type is suitable for the temperature range of -25°C to +60°C, and the cold-resistant type is suitable for -40°C to +60°C.
- Horizontal Force-bearing Capacity: In pot rubber bearings, the horizontal forces borne by fixed bearings, the transverse direction of longitudinal movable bearings, and the bridge direction of transverse movable bearings are related to the vertical load-bearing capacity, and there are different requirements in different seismic acceleration regions. For example, in the region where the peak acceleration ag≤0.1g, the horizontal force of the fixed bearing is 15% of the vertical load-bearing capacity.
- Friction Coefficient: In pot rubber bearings, when using polytetrafluoroethylene sliding plates with silicone grease lubrication, for the normal temperature type, μ≤0.03, and for the cold-resistant type, μ≤0.05; in slab rubber bearings, when the polytetrafluoroethylene plate is in contact with the stainless steel plate (with silicone grease), the friction coefficient μf = 0.06. When the temperature is lower than -25°C, the value of μf increases by 30%. When there is no silicone grease, the value of μf doubles.
