Hengshui Aohong Engineering Materials Co., Ltd.
Installation preparation stage
Install a bearing pad stone under the spherical bearing. The concrete strength of the bearing pad stone must be at least C40.
The height of the support pad stone should make it easy to install, maintain, and replace. The supporting pad stone must have a flat surface. You can leave the leveling layer thick. Then, use a polishing machine to grind it down to a flat surface.
For sloped bridges, align the bottom of the bridge beam with the steel plates that are pre-embedded. This applies to the length of the spherical bearing’s top plate.
The spherical bearing uses pre-embedded anchor sleeves and anchor bolts for connection. Also, the pier’s top surface must have anchor bolt holes. You should place these based on the specifications and number of anchor sleeves. The anchor bolt holes should be 50 mm to 60 mm wider and deeper than the casing’s diameter and length. The deviation of the center position of the reserved bolt hole should not exceed 10 mm.
The factory assembles the spherical bearing and ships it as a complete unit. Once the spherical bearings reach the construction site, unpack them. Check for any missing or damaged parts and compare them with the packing lists. You must not disassemble the support at will before installation.
To install the support, chisel the top surface of the support pad stone. Then, wash away the crushed stones and fine sand with clean water. Also, remove any debris from the anchor hole. Once the cushion stone dries, add a leveling layer of epoxy mortar on top. This should go outside the anchor bolt hole. Make sure the leveling layer is a bit higher than the support’s design elevation.
spherical bearings
Installation steps
Insert the anchor bolts into the holes of both support plates. Then, screw them into the steel sleeve. Add rubber pads between the steel sleeve and the upper and lower support plates. Then, tighten the anchor bolts.
Mark the centerline at the support’s design position. Mark the centerlines for the top and bottom plates. Do this in both the longitudinal and transverse directions. After keeping the support clean, place it in position. Find the pre-offset value for support displacement in the bridge direction. You need this if the installation temperature differs from the local average.
After setting and aligning the support, lock the upper and lower seat plates for the time being. This will keep the positioning structure intact during construction.
Align the support. Use steel wedges to level the support at the corners of the lower plate. The lower plate surface should be higher than the bridge pier top. For epoxy mortar, the height (h) should be 20-50 mm. For non-shrink cement mortar, h should be 30-80 mm. After leveling, pour epoxy or non-shrink cement mortar into the pre-drilled hole. This is for the anchoring steel sleeve and the bottom cushion layer of the support. After the epoxy mortar hardens, take out the temporary steel wedges from the four corners. Then, fill the spots where you removed the wedges with epoxy mortar.
After you install the beam body and the concrete sets, take off the temporary connection plates from both supports. This step is crucial to enable the beam body to rotate in the correct manner before prestressing. Check the working status of the supports.
Precautions for support installation.
The installer installs the support as a whole, and you cannot disassemble it at will. If the lifting equipment can’t hold much weight and needs to come apart, make sure to protect each separate part. Each decomposition product must not have any damage, pollution, or other phenomena. For movable supports, protect the polytetrafluoroethylene plates and stainless steel cold-rolled plates. This helps prevent scratches and dirt from sticking to their surfaces. When reassembling, check whether someone has filled the 5201-2 silicone grease.
Keep the top of the pier and the bottom of the beam clean, dry, and free of oil stains during installation. During installation, the support must avoid mechanical damage, burning, pollution, and other harm. The construction should maintain uniform stress throughout.
When you install the top plate of the movable support, think about how the installation temperature affects displacement. Check if the main sliding direction of the polytetrafluoroethylene board matches the bridge’s main displacement direction.
The centerline of the support should coincide with or be parallel to the centerline of the main beam. When installing a unidirectional movable support, ensure the guide block on the top plate aligns with the guide slider on the middle steel plate. Also, ensure that the intersection angle is no more than 5 degrees.
Once the team installs and checks the support, they should remove the temporary connectors linking the top and bottom plates. Then, they can install the support dust enclosure.
Spherical bearings change during installation based on the bridge construction method. Construction workers hold support plates for bridges. They do this while the main beams are being installed in place. The team lifts them together and then secures them in the design position. For bridges with prefabricated and hoisted main beams, you can fix only one seat plate at a time. This applies to either the upper or lower seat plate of the support. The construction crew starts by fixing the upper seat plate to the main beam. Then, they find the position of the bottom basin on the pier. Finally, they secure it.
To weld the support, first, put a flat steel plate on the pier support pad stone and beam body. Also, set many steel bars on the pre-embedded steel plate. Open exhaust holes on the steel plate to ensure the concrete stays compact. The area around the pre-embedded steel plate must be over 50 mm larger than the area around the support. Weld the pre-embedded steel plate and support in segments. Be careful with the temperature while welding. This helps prevent burning the PTFE and rubber plates. After welding, the team should carry out an anti-rust painting treatment.
