The performance of bridge bearings depends 70% on correct selection and 30% on proper installation. Selection errors can lead to bearing overload failure and incompatibility with deformation; improper installation can cause uneven pressure, loss of contact, jamming, and significantly shorten bearing service life. This article focuses on the two core aspects-selection and installation-and outlines practical specifications and control measures.
Precise Selection of Bridge Bearings - Following Three Core Principles
1. Selection Based on Load Capacity
The bearing capacity grade shall be determined based on the total dead load of the bridge superstructure, live vehicle loads, and additional loads. The design bearing capacity shall include a safety factor of 1.2 to 1.5 times to avoid long-term overload, which can cause rubber cracking and steel component deformation. For small- and medium-span simply supported beams, laminated rubber bearings shall be selected; for large-span and heavy-load beams, pot bearings or spherical bearings shall be used.
2. Selection Based on Displacement and Rotation
Calculate the horizontal displacement and rotation amplitude caused by temperature deformation, concrete creep, and braking forces:
- For small displacement and small rotation → laminated rubber bearings
- For large displacement and large rotation → sliding pot bearings
- For multi-directional rotation → spherical bearings
In seismic zones, additional seismic displacement requirements shall be considered, and seismic isolation bearings shall be selected.
3. Selection Based on Environment and Bridge Type
- In severely cold regions, cold-resistant rubber materials shall be used.
- In coastal and corrosive environments, stainless steel and anti-corrosion coated bearings shall be used.
- For high-speed railway bridges, high-precision spherical bearings shall be selected.
- For cable-stayed bridges and arch bridges, universal spherical hinges shall be selected.
- Ensure the bearing is suitable for the site environment and bridge structural type.
Standard Installation Process for Bridge Bearings - Strict Control Over Each Step
1. Preparation: Substrate Treatment and Inspection
The top surface of the pier shall be flat, clean, and free of cracks, with elevation error controlled within ±1 mm. The embedded steel plate shall be level, free of rust and debris. Verify the bearing model, specifications, and certificate; check for damage, scratches on sliding plates, and intact seals.
2. Accurate Positioning: Lifting and Alignment
Use dedicated lifting gear to avoid impact and overturning. Position the bearing strictly according to design coordinates: fixed bearings shall be perfectly centered; sliding bearings shall have preset offset (to accommodate temperature displacement). Ensure the bearing center aligns with the beam and pier center to avoid eccentric loading.
3. Fixing and Adjustment: Tightening and Inspection
Connections between the bearing, beam, and pier shall be secure. Welding shall be performed without damaging rubber components. When lowering the beam, apply pressure slowly and evenly to ensure full contact, no loss of bearing contact, and no uneven pressure. After installation, check sliding flexibility and rotational freedom, clean the site, and apply anti-corrosion sealing.
4. Finished Product Protection: Damage Prevention
Immediately after installation, cover with dustproof and waterproof protective film to prevent contamination or damage from concrete pouring or welding. Subsequent construction shall avoid impact or heavy pressure on the bearing.
Installation Taboos:
Forcing the bearing into position, installing beyond allowable eccentricity, or omitting anti-corrosion sealing steps is strictly prohibited. Any of these will directly lead to premature bearing failure.