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How to determine the size of elastomeric bearings?

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For elastomeric bearing, the vertical load is resisted by its compression while shear resistance of the bearing controls the horizontal movements.

The design of elastomeric bearings is based on striking a balance between the provision of sufficient stiffness to resist high compressive force and the flexibility to allow for translation and rotation movement.

The cross sectional area is normally determined by the allowable pressure on the bearing support. Sometimes, the plan area of bearings is controlled by the maximum allowable compressive stress arising from the consideration of delamination of elastomer from steel plates. In addition, the size of elastomeric bearings is also influenced by considering the separation between the structure and the edge of bearing which may occur in rotation because tensile stresses deriving from separation may cause delamination. 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 certain limit to avoid the occurrence of rolling over and fatigue damage. The vertical stiffness of bearings is obtained by inserting sufficient number of steel plates.

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This question is taken from book named – A Self Learning Manual – Mastering Different Fields of Civil Engineering Works (VC-Q-A-Method) by Vincent T. H. CHU.

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Comments
  • ashish bhoi August 21, 2010 at 1:59 pm

    hi,

    I have designed a elastomeric bearing for semi through type plate girder railway bridge. but i have some problem regarding chose a appropriate dimension. thou i have chose a section for the designed bridge but it’s min vertical stress is less dan 2 MPa .in that case can we provide anti creep device and apporve the same. As the main problem here is difference between DL & LL is so high dat i can’t chose a appropriate dimension.
    If u have any sample calculation for elastomeric bearing design (as per BS5400 Or IRC-83(part-II) den please forward me ……………………

    thanks

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