ESDU 83009:2012

ESDU 83009 provides damping data for the estimation of the small
amplitude response of tall buildings to wind excitation. Data
enable the modal damping, expressed as a fraction of critical
damping, to be estimated for the first translational modes of
vibration parallel to the two principal axes of deformation. The
method applies to buildings of regular construction over 20 m (65
ft) tall. The modal damping ratio is given by the sum of the modal
structural and aerodynamic damping ratios. The modal structural
damping ratio may be estimated from simple design charts based on
full-scale measurements, and the modal aerodynamic damping ratio is
given by simple formulae. The effect of foundation damping is
discussed. The mechanisms of damping in a tall building are
explained, and the effect of increasing amplitude of vibration on
the modal damping is discussed. Full-scale test results illustrate
the effect. Methods of measuring the modal damping, with an
explanation of the accuracy of measured values, are outlined.
Various techniques for increasing the modal damping are considered.
The mode-generalised parameters required for the response
calculations by the normal-mode method are presented, and their
application in the design of damped scale models of full-scale
buildings is discussed. Other modal damping expressions commonly
used in the study of tall building response are given.