Difference of modal to modal with automatic definitions of seismic cases.

[C30/37]

1st question: What is the difference between modal and modal with automatic definitions of seismic cases and when someone should chose one instead of the other.

The options at the second choice also include 1. eccentricity parameters, 2. Seismic analysis parameters e.g. En1998, 3. In modal analysis parameters there is the option of "analysis mode: seismic).

The second question is: If I choose "modal with automatic definitions of seismic cases" and set all the above parameters, do I still have to create another NEW analysis type, e.g. seismic and define these parameters again?

Third question: With what kind of analysis can I combine "modal with automatic definitions of seismic cases"?

Fourth question: When should I choose "analysis mode" ->seismic in modal analysis and when should I choose modal?

Is there an example of step by step (having all steps) of how to define and run a seismic analysis (either dynamic or equivalent lateral force), with eccentricities?

Last but not least, when I create various kinds of seismic analysis and I choose Newmark combinations I get all the combinations accounting for the directions of seismic forces but they are not combined with Dead and Live loads. At least they do not appear at combinations table. Am I doing something wrong?

Thank you in advance

[Artur.Kosakowski · Accepted solution]

1st question: What is the difference between modal and modal with automatic definitions of seismic cases and when someone should chose one instead of the other.

There is no difference provided that after modal analysis you define seismic ones. This is just as defining manual combinations one by one using Loads > Manual Combinations or with help of the kind of a wizard Loads > Automatic Combinations > Manual Combinations - generate

Is there an example of step by step (having all steps) of how to define and run a seismic analysis (either dynamic or equivalent lateral force), with eccentricities?

It is the same definition as for the seismic analysis without them. The only difference is that you add these values so you may have several modal analysis followed by seismic ones such as: modal with +X +Y eccentricity followed by seismic cases then modal +X -Y followed by seismic cases etc.

Last but not least, when I create various kinds of seismic analysis and I choose Newmark combinations I get all the combinations accounting for the directions of seismic forces but they are not combined with Dead and Live loads. At least they do not appear at combinations table. 

You need to define additional combinations which include dead and live load cases and one of the Newmark combinations.

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