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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