Pot Bearing Specifications

(1) A support pad should be set under the pot-type bearing. The concrete strength grade of the support pad should not be lower than C40. The height of the pad should take into account the convenience of bearing installation, maintenance and replacement. The support pad and pier top concrete should be equipped with corresponding steel mesh according to the requirements of local pressure-bearing parts in JTG D62-2004. Bolt holes should be reserved on the top surface of the pier according to the specifications and quantity of the anchor sleeve. The diameter and depth of the reserved bolt hole should be 50mm~60mm larger than the diameter and length of the sleeve, and the center deviation should not exceed 10mm.

(2) After the bearing is transported to the site, the parts and packing list of the bearing should be unpacked and checked. After the inspection is qualified, they can be put into the packaging box and unpacked for installation.

(3) After unpacking the movable bearing, attention should be paid to the protection of the polytetrafluoroethylene plate and stainless steel cold-rolled steel plate to prevent scratches or dirt from adhering to the surface of the polytetrafluoroethylene plate and cold-rolled steel plate, and check whether the 5201-2 silicone grease is filled.

(4) When installing the bearing, the top surface of the supporting cushion stone should be roughened and the debris on the cushion stone should be washed away with clean water. After the surface of the cushion stone is dry, the top surface of the supporting cushion stone outside the anchor bolt hole position should be coated with epoxy mortar leveling layer. After the bearing is in place, centered and adjusted to the level, the bearing is padded with pads, and the gap around the sleeve and the position around the bearing bottom plate that is not filled with epoxy mortar are poured with epoxy mortar or mortar with higher strength grade, and the mortar is compacted. After completion, the mortar overflowing outside the bearing bottom plate should be cleaned up, and the bearing pads should be removed after the mortar hardens.

(5) For bridges with longitudinal slopes, the bottom of the bridge beam within the length range of the bearing top plate should be straightened and leveled with embedded steel plates during design. The concrete within the range of the bearing top plate should be calculated for local bearing pressure according to JTG D62-2004 and the corresponding steel mesh should be configured. Temperature changes should be considered when installing movable bearings.

(6) When installing bidirectional and unidirectional movable bearings, special attention should be paid to checking the polytetrafluoroethylene sheet. The main sliding direction of the polytetrafluoroethylene sheet should be consistent with the longitudinal direction of the bridge.

(7) The center line of the bearing should coincide with or be parallel to the center line of the main beam. When installing unidirectional movable bearings, the guide slides of the top plate guide block and the middle steel plate should remain parallel, and the crossing angle should not exceed 5′.

(8) When cutting and installing temporary anchors for bridge system conversion, insulation measures should be taken to avoid damage to the rubber sheet and polytetrafluoroethylene sheet.

(9) After the installation is completed and the inspection is qualified, the connecting components should be removed and the dustproof enclosure should be installed.

The layout of bridge bearings is mainly related to the structural form of the bridge. The following basic principles should usually be considered when arranging bearings:

(1) When the superstructure is a spatial structure, the bearings should be able to adapt to the deformation of the bridge in the longitudinal direction (X direction) and the transverse direction (Y direction) at the same time;

(2) The bearings must be able to reliably transmit vertical and horizontal reaction forces;

(3) The bearings should ensure that the longitudinal displacement, transverse displacement and longitudinal and constant rotation angles caused by the deformation of the beam body are as unconstrained as possible;

(4) Railway bridges usually have to have a fixed bearing on each beam body;

(5) When the bridge is located on a ramp, the fixed bearing should generally be located on the abutment in the downhill direction;

(6) When the bridge is located on a flat slope, the fixed bearing should be located on the front abutment in the main driving direction;

(7) The fixed bearing should be located in a place with a large bearing reaction force;

(8) Several bearings on the same pier should have similar rotational stiffness;

(9) When the continuous beam may experience bearing sinking, the possibility of adjusting the manufacturing height should be considered.

In short, the layout principle of bridge bearings is to facilitate the transmission of bearing reaction forces and to enable the bearings to fully adapt to the free deformation of the beam body.