Precautions for Bridge Bearing Layout

Precautions for Bridge Bearing Layout:

The arrangement of bridge supports is mainly determined based on the structural form and width of the bridge

A simply supported beam bridge is equipped with fixed supports at one end and movable supports at the other end Due to the small width of railway bridges, the lateral displacement of bearings is minimal, and generally only unidirectional movable bearings (longitudinal movable bearings) need to be installed. For highway T-beam bridges, the possibility of lateral movement of bearings needs to be considered due to the wide bridge deck; Namely, a fixed support is set on the fixed pier, adjacent supports are set as unidirectional movable supports that are horizontally movable and vertically fixed, while a longitudinal movable support (corresponding to the fixed support) is set on the movable pier, and multi-directional movable supports are set on the rest.

Plate rubber bearing is a simple rubber bearing made of only one rubber plate, suitable for medium and small span bridges. Its working mechanism is to use the uneven elastic compression of rubber to achieve turning angle, and use its shear deformation to achieve horizontal displacement.

Due to the sufficient frictional resistance between rubber and steel or concrete (friction coefficient of 0.25~0.40), there is generally no need to connect the rubber plate to the bottom of the beam and the top of the pier At the top of the pier, a layer of mortar needs to be laid to ensure that the support is placed smoothly. Rubber bearings can be used without fixed bearings, and all horizontal forces are evenly distributed among the bearings. If necessary, uneven height rubber plates can also be used to adjust the horizontal forces transmitted by each bearing.

Each continuous beam bridge is equipped with only one fixed support. To avoid excessive expansion joints at the active end of the beam; The fixed support should be placed on the middle pivot point of each pair. But if the pier body is relatively high, special measures should be considered to avoid or take measures to prevent the pier body from bearing excessive horizontal forces.

When the bridge is located on a slope, the fixed support should be set at the lower end to allow the beam to be compressed under the force of the vertical load along the slope direction, so as to offset some of the tension generated by the vertical load on the lower edge of the beam. When the bridge is located on a flat slope, the fixed support should be set at the front end of the main driving direction.