topic Modal with automatic definition of seismic cases vs one modal and seismic cases in Robot Structural Analysis Forum

Modal with automatic definition of seismic cases vs one modal and seismic cases

Anonymous — Sat, 06 May 2017 07:30:37 GMT

Hi,

I wish to clarify about the definition of seismic cases via the "Modal with automatic definition of seismic cases." I understand based on webinar discussing this that using this option generates several modal analysis cases with different eccentricities based on the options given. I chanced upon the situation wherein I only manually defined one modal analysis without any eccentricity defined, after which when I defined a succeeding seismic case, I was given the option to define the eccentricity. This option is not shown if the automatic version is used. I want to clarify if this option is similar to the automatic one? If so, this seemed preferable since the model only needs to run one modal analysis instead of several.

Thank you,

Rico

Re: Modal with automatic definition of seismic cases vs one modal and seismic ca

Artur.Kosakowski — Mon, 08 May 2017 12:16:24 GMT

Hi Rico,

You can define the same parameters in either of the ways provided you selected the same parameters. Unless you define the mass eccentricity with the simplified approach you need to define as many modal analyses and many different eccentricities you want to have.

If you find your post answered press the Accept as Solution button please. This will help other users to find solutions much faster. Thank you.

Re: Modal with automatic definition of seismic cases vs one modal and seismic ca

Anonymous — Mon, 08 May 2017 12:01:22 GMT

Thank you for clarifying Artur. I did try to compare results using both and there are only small numerical differences.