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Number of modes of 3D model

Number of modes of 3D model

Number of modes of 3D model

(OP)
Hi,

I am performing a model analysis using eigenvectors.

I have a 3D structure that has all translational and rotational dof's active which requires over 90 modes to obtain a mass participation ratio of 90% in all translational directions. The structure is inclined, which means that non-lateral movement has UX and UZ components, which slows down the process of obtaining a satisfactory mass participation ratio. Further, I have many modes in a row which contribute with practically zero to the response because only a very small part of the structure is moving.

Does anyone know a trick to eliminate these insignificant modes from the eigen modal analysis? I see that advanced load parameters can be specified but I don't know if this might help me somehow..

Thanks :)

RE: Number of modes of 3D model

(OP)
Also, I can't find any information on the frequency shift, cutoff frequency and convergence tolerance - maybe they can help me get rid of the modes that do not contribute?

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