What are the applications of special bearings for highway bridges in coastal areas
Special bearings for highway bridges have various applications in coastal areas. The following are some common types and application scenarios:
1. Seismic isolation bearings
Application scenario: Earthquake activity may be more frequent in coastal areas, and strong winds, waves, and other effects can also have dynamic effects on bridges. The Zhangshan high-speed railway (Guangdong section
Special bearings for highway bridges have various applications in coastal areas. The following are some common types and application scenarios:
1. Seismic isolation bearings
Application scenario: Earthquake activity may be more frequent in coastal areas, and strong winds, waves, and other effects can also have dynamic effects on bridges. The Zhangshan high-speed railway (Guangdong section) adopts hyperbolic spherical seismic isolation bearings, longitudinal elastic constrained seismic isolation bearings, etc.
Working principle: Seismic isolation bearings have a large horizontal deformation capacity and appropriate damping characteristics through special materials and structural design. During an earthquake, it can extend the natural vibration period of the structure and reduce the seismic force transmitted to the bridge structure; In the vibration caused by strong winds or waves, it can effectively dissipate energy, reduce the vibration response of bridges, and protect the safety of bridge structures.
2. High performance PTFE skateboard support
Application scenario: It has been applied in large cross sea bridges such as Huangmaohai Bridge.
Working principle: High performance polytetrafluoroethylene sliding plates have a low coefficient of friction, which can make the beam slide smoothly on the support when subjected to small displacements caused by temperature changes, concrete creep and shrinkage, and vehicle driving, reducing the friction force between the beam and the bridge pier and reducing the additional internal forces generated on the beam and bridge pier structure. At the same time, the material has good chemical stability and can resist long-term erosion from seawater, salt spray, and other chemical substances, making it suitable for strong corrosive environments along the coast.
3. Tension compression support
Application scenario: Used to enhance the impact resistance of coastal box girder bridges under extreme wave conditions.
Working principle: The tension compression support is usually an optimization and upgrade of the existing plate rubber support system, consisting of plate rubber supports and pull-out stoppers (upper and lower plates). When the upper and lower plates are not in contact, the working mode is similar to that of ordinary plate rubber bearings; When the wave force exceeds the self weight of the upper structure, the upper and lower plates of the support will come into contact, imposing constraints on the upper structure and limiting excessive sliding or shear deformation of the rubber layer, thereby enhancing the bearing capacity and stability of the bridge under extreme wave action.
4. Rubber bearings with protective devices
Application scenario: Highway bridges in coastal areas commonly use rubber bearings and are equipped with corresponding protective devices.
Working principle: Rubber bearings themselves have good elasticity and shock absorption performance, which can effectively absorb and disperse the weight of the bridge structure itself and the vibration energy from the external environment. In coastal environments, to prevent rubber bearings from being affected by salt erosion, sand and dust wear, they are usually equipped with protective devices such as dust covers. Dust covers are generally made of weather resistant materials such as chloroprene rubber, polyurethane, etc., which can prevent impurities such as dust, oil, and moisture from entering the interior of the support, maintain the smoothness of the support surface, reduce sliding resistance, maintain the performance of the support, and extend its service life.
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