Rayleigh Damping Command

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This command is used to assign damping to all previously-defined elements and nodes. When using rayleigh damping in OpenSees, the damping matrix for an element or node, D is specified as a combination of stiffness and mass-proportional damping matrices:

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

rayleigh $alphaM $betaK $betaKinit $betaKcomm

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$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.

NOTE:

1. The command overwrites any existing damping coeeficients at the Elements and Nodes.
2. The following paper is something that you should read if you are new to the damping and nonlinear analysis. Finley A. Charney, "Unintended Consequences of Modeling Damping in Structures", J. Struct. Engrg. Volume 134, Issue 4, pp. 581-592 (April 2008) DOI
3. Other useful papers to read:
   1. Petrini, Lorenza , Maggi, Claudio , Priestley, M. J. Nigel and Calvi, G. Michele (2008) "Experimental Verification of Viscous Damping Modeling for Inelastic Time History Analyzes", Journal of Earthquake Engineering, 12:S1, pp. 125 — 145 DOI
   2. Hall, J. F.(2006) "Problems encountered from the use (or misuse) of Rayleigh damping," Earthquake Engineering and Structural Dynamic, 35, 525–545 DOI

EXAMPLE:

rayleigh 0.01 0.02 0.0 0.0

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Code Developed by: fmk