1. General

There are two classes of systems:

• conservative systems for which there is a constant exchange between the two forms of energy: kinetic and potential (i.e. deformation energy of structural elements);

• dissipative systems for which it has been decided to mitigate the effects by using a dissipative energy damper, which can be :

  • fluid: pressure losses due to fluid viscosity are used,

  • with solid friction,

  • with structural dissipation.

Systems can also be :

• discrete: there is a finite number of position parameters whose evolution over time is being investigated; we shall see that it is in this situation that the investigations...