This is
the force displacement plot generated by
the shear testing of an isolator.
Elastic Stiffness, Ke:
This is
the initial stiffness of the isolator, typically
at less than one inch displacement. Its
value is dominated by the lead core size
and is important in controlling the response
to services loads such such as wind.
Yielded Stiffness, Kd or K2:
This is
the secondary stiffness of the isolator
and is a function of the modulus, total
height and area of the rubber.
Keff (Effective Stiffness)
This is the isolator force divided
by the displacement. This is a displacement-dependent
quantity.
Hysteretic Strength, Qd:
This is
the force axis intercept of the isolator
hysteresis loop. This parameter relates
to damping and isolator response to service
loads.
Yield Force, Fy:
The yield
force is the point in the model at which
the initial stiffness changes to secondary
stiffness. In reality, there is a smooth
transition from one stiffness to the other,
rather than a well-defined point. This value
is mainly used in analytical modeling.
Energy Dissipated per Cycle,
EDC:
This is
the area of the hysteresis loop. This value
is a measure of the damping of the isolator.
Vertical Stiffiness (Ky)
This is the vertical stiffness
of the isolator.
DBE (Design Basis Earthquake):
DBE represents
the ground motion that has a 10% chance
of being exceeded in 50 years.
MCE (Maximum Credible Earthquake):
MCE is defined
as the ground motion that has a 2% probability
of being exceeded in 50 years
