ABSTRACT
Early in the studies of the damping behaviour of structures, the concept of an 'equivalent viscous damping value' was introduced. This allowed the use of convenient mathematical equations, which assume that such a mechanism exists despite the fact that the mechanism was clearly not operating. Whilst this simplified many aspects of the calculation of dynamic behaviour, it also left a legacy of misunderstanding, and in particular it was an invitation to forget that damping is non-linear in the vast majority of cases. Luckily, some recent work by Wyatt (1977) has shown that a multitude of friction mechanisms, which are clearly present in structures, when summed over a range of amplitudes, actually produce a result that looks like a viscous-type response. Truly, we now have the complete physical picture for the implementation of the equivalent viscous damping approach, which also happens to explain why non-linearities should be expected.
