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Damping matrix multi degrees of freedom

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Batzo

Batzo

Civil/Environmental
Apr 21, 2020
46
IL
Hi,
In mdof I have those matrices:
yJziQl2_lhv1o6.jpg

IMG_20210812_195135_x0ikbh.jpg


I have m and k, how do I find c? [ponder]
 
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Typically with damping, you just assume something.
 
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Ok, i assume 5% damping ratio.
What next?
 
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I want to calculate "c". I have m and k.
Assuming damping ratio 5%,
What method to use?
What are the equations?
Can u show me the calculation?
 
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Do you have any of the other parameters? Acceleration? What is the displacement?
 
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I have building and forces properties:
16287897193077122806836843366051_fwzsmd.jpg


But those are not relevant...
I have no displacement / acceleration.

Can I use
c=2*zeta*m*wn ?
I want to use central difference method as in biggs book (1964)
 
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I want to calculate "c". I have m and k.
Assuming damping ratio 5%,
What method to use?
What are the equations?
Can u show me the calculation?
Click to expand...

You just said you just said you were going to assume damping. But in any case, if you have Tedesco's Structural Dynamics book, see example problems 12.2 through 12.6.
 
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I have tried using rayleigh...
but the matrix in position c(3,3) is not equal to -c(2,3):
From chopra
16287935432816314540680120852597_wwm5xa.jpg
 
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