Dashpot damping - dashpt

This is a two-node damping element, which may be employed to represent a linear dashpot between any two given nodes, e.g. it can be used to represent a damper installed on a steel brace. Damping coefficients may be defined on all six global degrees-of-freedom, though, commonly, dampers will work only in one or two directions. The dashpot accounts for the relative motion between two element nodes, in order to calculate the dashpot forces.

Notes

1. In SeismoStruct, dampers are normally modelled by means of link elements with adequate response curves that may be able to characterise the non-velocity-dependent (at least within the typical range of earthquake velocities) force-displacement relationship of a given damper. However, in those cases where velocity dependence is important, this dashpt element may be employed instead, noting that currently only a linear force-velocity relationship is featured.
2. This dashpt element may also be employed whenever the need arises for the introduction of a Maxwell model (i.e. series coupling of damping and stiffness), by placing in series a link and a dashpt element. For a Kelvin-Voigt model (i.e. parallel coupling of damping and stiffness), one may again make use of a link element, this time placed in parallel with a dashpt, though in these cases it may result easier to simply assign directly to the link element a given viscous damping value.