Please provide details about rayleigh damping in OpenSEES?

[dasgovind]

how to apply rayleigh damping in opensees, when a pulse load is applied on a shallow foundation.

[fmk]

rayleigh damping is applied with the rayleigh command .. what additional info do you actually want??

[dasgovind]

How to calculate mass proportional and stiffness proportional damping. ? And what is the role of eigen analysis. ?

[giovannimilan]

dasgovind wrote:
> How to calculate mass proportional and stiffness proportional damping. ?
> And what is the role of eigen analysis. ?


The rayleigh damping is a way to construct the damping matrix in a classical formulation. It is a viscous damping that is proportional to a linear combination of mass and stiffness.

It achieves a damping ratio for the structure that varies with its frequency of vibration. This does not seem to reflect the experimental measurements. For which the damping ratio seems to be constant along the modes of the structure.

The eigen value analysis is necessary priory to determine the fundamental modes of the system, and make sure that the damping ratios are of a certain desired value close to those.

This is a good example:

http://opensees.berkeley.edu/wiki/index ... ment_Frame

For the theory behind, I suggest the book by Chopra - Dynamics of structures.