## Robot Structural Analysis

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# Seismic analysis and eccentricity

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Dear friends,

We have 3 type of eccentricity in Robot:

e0 - eccentricity between center of rigidity and center of gravity. It's based on our model.

e1 - accidental eccentricity. It's equal 5% from story dimension perpendicular to the direction of a seismic action.

e2 - additional eccentricity. We can define it in properties for Modal analysis for example:

Can you explain to me how Robot take into account values of eccentricity? It's like e=e0+e1+e2 or another?

Solved! Go to Solution.

# Re: Seismic analysis and eccentricity

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e1 and e2 is just the different way of defining the same parameter. It is either or choice of the way the accidental eccentricity is taken into account.

e = e0 + e1 or e = e0 + e2

See also message 2 from http://forums.autodesk.com/t5/Autodesk-Robot-Struc

*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.*

**Artur Kosakowski**

# Re: Seismic analysis and eccentricity

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# Re: Seismic analysis and eccentricity

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If you don't enter any values in the parameters of modal and seismic case then e = e0.

*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.*

**Artur Kosakowski**

# Re: Seismic analysis and eccentricity

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# Re: Seismic analysis and eccentricity

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I'm sorry I missed the fact that you referred to the stories table and incorrectly assumed that e1 and 2 referred to the way you define eccentricities (in a modal or a seismic case).

Using the values as in the table you attached e1 is just informative (not used in calculations) and is based on the 5% offset (as not used in calculations the direction is irrelevant).

e2 is what you define in either modal or seismic case therefore e = e0 + e2. Regarding the directions you should provide signs yourself therefore more than one modal or one seismic case in given direction may be needed. E.g. for the eccentricities defined in the modal analysis:

X 5%; Y 5%

X 5%; Y -5%

X -5%, Y -5%

X -5%; Y 5%

*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.*

**Artur Kosakowski**

# Re: Seismic analysis and eccentricity

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