Rayleigh Damping Command

[aminkotb]

D = $alphaM * M + $betaK * Kcurrent +$betaKinit * Kinit + $betaKcomm * KlastCommit

rayleigh $alphaM $betaK $betaKinit $betaKcomm

$alphaM factor applied to elements or nodes mass matrix
$betaK factor applied to elements current stiffness matrix.
$betaKinit factor applied to elements initial stiffness matrix.
$betaKcomm factor applied to elements committed stiffness matrix.

please clarify the difference between ( $betaK $betaKinit $betaKcomm), what is the stiffness matrix used in each case.

does $betaK mean that the stiffness matrix generated from the last nonlinear gravity analysis is used and remain constant during the dynamic analysis?
does $betaKinit mean that the stiffness matrix generated from the initial linear case (undeformed case) ?
does $betaKcomm mean that the stiffness matrix generated from the nonlinear case and at every step in the dynamic analysis it will change to a new one (not constant in the dynamic analysis)?



In the examples on the site, I found that most soil problems use ($alphaM $betaK), while in structure uses ($alphaM $betaKinit ) or ( $betaKcomm ) only. is there a reason for that?

I have another question regarding the use of Region Command with Rayleigh damping (can I used both mass and stiffness coefficient for element and its nodes or do i need to do each one separately )

[sairamkatikala]

Hello friend,

There is a journal paper in the references. Please go through that. You will get clear idea about damping command.