How to obtain normalized mode of Opensees model?

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pp_0928
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How to obtain normalized mode of Opensees model?

Post by pp_0928 »

Dear Sir or Madam,

I want to do the modal analysis and obtain normalized mode for my Opensees model.

I saw a command "printA", and tested it in the most simplest example (elastic SDOF) in Opnesees example manual.
The result is 3X3 matrix as follows:

"679.495 0 146771
0 3.5225e+010 0
146771 0 4.227e+007 "

I don't know how this matrix construct, which part is stiffness matrix and which part is mass?

Or is there any convenient way to obtain normalized mode matrix (phi) in Opensees?

Many thanks
fmk
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Re: How to obtain normalized mode of Opensees model?

Post by fmk »

the mapping betweeen dof and equation numbers can be seen the ID's given at the nodes .. issue a "print node" command to see them .. this is true for all situations except the case where you have MP constraints.

the MASS part of the matrix should be pretty obvious! remember this is the total stiffness matrix, if a static analysis this matrix is just the K, if transient it can be a mix of K, M and C.
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