What are the installation steps for rubber bearings used in highway engineering?
The installation quality of rubber bearings used in highway engineering directly affects the service performance and lifespan of bridges. Although there are differences in the installation steps of different types of rubber bearings, the general process is similar. The following are the general installation steps:
Construction Preparation
Material and Tool Preparation: According to the design requirements, prepare rubber bearings of corresponding specifications and models. At the same time, prepare the tools required for installation, such as a level, jacks, steel tapes, wrenches, etc., as well as necessary auxiliary materials, such as epoxy mortar, stainless steel plates (for bearings with sliding requirements), etc.
Bearing Inspection: Before installation, conduct a visual inspection of the rubber bearings to check for any defects such as cracks, bubbles, and delamination. Check whether the specifications, dimensions, and performance indicators of the bearings meet the design requirements to ensure that the bearings are of qualified quality.
Pier, Abutment and Girder Inspection: Check the flatness, elevation, and centerline position of the top surface of the pier and abutment and the bottom surface of the girder to see if they meet the design requirements. Clean up the sundries, oil stains, dust, etc. on the top surface of the pier and abutment and the bottom surface of the girder to ensure that the installation surface is clean and flat.
Surveying and Setting Out
Determine the Center Position of the Bearing: According to the design drawings, mark out the longitudinal and transverse centerlines of the bearing on the top surface of the pier and abutment and the bottom surface of the girder respectively. Use a level to measure the elevation of the top surface of the pier and abutment to ensure that it meets the design elevation.
Set Elevation Control Points: Set elevation control points at appropriate positions around the pier and abutment to accurately control the elevation of the bearing during the installation process.
Installation of the Bearing Pad Stone (if any)
Pouring the Pad Stone: If the design requires the installation of a bearing pad stone, set up the formwork on the top surface of the pier and abutment according to the design dimensions, and pour the concrete bearing pad stone. The concrete strength grade of the pad stone should meet the design requirements, and the surface should be flat and smooth, with the elevation error within the allowable range.
Installation of the Embedded Steel Plate: When pouring the concrete of the pad stone, embed the steel plate in the designed position to ensure that the levelness and center position of the steel plate are accurate. The surface of the embedded steel plate should be treated with anti-rust measures.
Installation of Rubber Bearings
Installation of Slab Rubber Bearings
Applying Adhesive: Apply a thin layer of epoxy mortar or other bonding materials on the top surface of the pier and abutment or the bearing pad stone to enhance the bonding force between the bearing and the pier and abutment.
Placing the Bearing: Place the rubber bearing accurately in the predetermined position, aligning the centerline of the bearing with the centerline marked on the top surface of the pier and abutment or the pad stone.
Adjusting the Elevation: Use a jack to fine-tune the elevation of the girder to make the bearing evenly stressed and ensure that the upper surface of the bearing is in close contact with the bottom surface of the girder.
Installation of Pot Rubber Bearings
Installation of the Lower Bearing Plate: Place the lower bearing plate on the top surface of the pier and abutment or the bearing pad stone, and fix it with the embedded steel plate using bolts. Adjust the levelness and center position of the lower bearing plate to make it meet the design requirements.
Installation of the Rubber Block and the Sealing Ring: Put the rubber block into the pit of the lower bearing plate and install the sealing ring to ensure a good seal.
Installation of the Upper Bearing Plate: Before hoisting the girder, connect and fix the upper bearing plate with the embedded steel plate on the bottom surface of the girder using bolts. After the girder is hoisted in place, accurately align the upper bearing plate with the lower bearing plate, and then install the intermediate steel plate and the polytetrafluoroethylene sliding plate (if any).
Fixed Connection: Install the connection bolts of the bearing and adjust the tightness of the bolts to ensure that all components of the bearing are firmly connected.
Installation of Spherical Rubber Bearings
Installation of the Lower Bearing Plate: Similar to the installation method of the lower bearing plate of the pot rubber bearing, fix the lower bearing plate on the top surface of the pier and abutment or the bearing pad stone to ensure that its levelness and center position meet the requirements.
Installation of the Ball Core and the Upper Bearing Plate: First, install the ball core in the ball socket of the lower bearing plate, and then connect and fix the upper bearing plate with the embedded steel plate on the bottom surface of the girder. After the girder is hoisted in place, accurately align the spherical crown of the upper bearing plate with the ball core and install the connection parts.
Adjustment and Fixation: Check the installation condition of the bearing, adjust the position and elevation of the bearing to make it meet the design requirements. Finally, tighten all the connection bolts to fix the bearing.
Inspection and Acceptance
Visual Inspection: After the installation is completed, inspect the appearance of the rubber bearing to check for any deformation, displacement, damage, etc.
Elevation and Position Inspection: Use measuring tools such as a level and a steel tape to check whether the elevation and center position of the bearing meet the design requirements, and the error should be within the allowable range.
Bearing Load-bearing Inspection: After the girder is installed, check whether the bearing is evenly stressed. If there is any situation of individual bearing being empty or unevenly stressed, adjust and deal with it in a timely manner.
Acceptance Records: Keep records of the installation process and carry out the acceptance work carefully. Organize the relevant materials to ensure that the installation quality of the rubber bearing meets the specifications and design requirements.
The above are the general installation steps for rubber bearings used in highway engineering. In actual construction, according to the specific bearing type and project requirements, the installation operation should be carried out strictly in accordance with relevant specifications and design documents.
