Effect of various factors on spectral values
Viscous Damping

Viscous damping is a convenient analytical concept to account for general energy dissipation and analytical uncertainties. Viscous damping is usually used to represent the following:

  • Friction between and with structural and non-structural elements
  • Localized yielding due to stress concentrations and residual stresses under low loading and gross yielding under higher loads
  • Energy radiation through foundation
  • Aeroelastic damping
  • Viscous damping
  • Analytical modeling errors

Viscous Damping Values for Design

Many codes stipulate 5% viscous damping unless a more properly substantiated value can be used. Note that actual damping values for many systems, even at higher levels of excitation are less than 5%.