Viscous damping acts 90oout of phase
with structural bending. It fattens the hysteresis loop.
Optimum values for C & n must be found. (n = .4
for San Bernardino Medical Center,
.75 for Golden Gate) and the best number of dampers and locations must also be found.
The initial model should be fairly simple, and could
use modal analysis with dampers
represented as modal damping (n = l.0). We know that 20% to 30% works well. This initial model can determine the optimum
A later model should be a finite element detailed
model with discrete damper elements.It should permit nonlinear damping
(“n" that is other than 1.0). This model will provide an estimate of the number and
location of dampers as well as their
force and velocity requirements.At
this stage a two dimensional model should be sufficient.
Later, if the structure is torsional, it may be
necessary to proceed with a three dimensional finite element model.