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size of elastomeric bearings

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Elastomeric bearings are made of layers of synthetic chloroprene rubber (CR) or natural rubber (NR). Steel plates are placed between rubber layers, rubber layer will be merged by vulcanization to produce a single pad. The elastomeric bearing will allow for rotation of superstructure. Movement of the superstructure will be accommodated through elastic deformation.
Figure 1








Elastomeric bearing resisting vertical loads by elastomeric compression. While the shear resistance of the bearing will control superstructure movement. The elastomeric bearing should be designed to provide a balance between stiffness to resist vertical load and flexibility to allow for bridge movement. The cross-section of elastomeric bearing determined based on the allowable pressure on the bearing support. In some cases, the maximum compression stress is controlled and determined based on the consideration for the delamination of elastomer and steel plate. The possible delamination as a result of tensile stress due to the separation of bearing edge during the rotation should be considered in determining the bearing size.  The thickness of bearings is designed based on the limitation of its horizontal stiffness and is controlled by movement requirements. The shear strain should be less than a specific limit to avoid the occurrence of rolling over and fatigue damage. The vertical stiffness of bearings is obtained by inserting a sufficient number of steel plates.



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