## Robot Structural Analysis

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# Seismic analysis: parameter lambda

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Referring to EC8-4.3.3.2.2(1) and the parameter lambda (correction factor related to number of levels), where can I find the value used by Robot for seismic analysis? It seems to be omitted from the calculation note.

Thanks!

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# Re: Seismic analysis: parameter lambda

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My understanding is that you refer to the lateral forces method whereas in Robot the modal response spectral analysis (4.3.3.3) is used instead.

*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: parameter lambda

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Ah, that makes sense, now that you say it. However, what I was really going for, was to check the result of the modal analysis. Shouldn't the sum of reactions (Fx) from the seismic analysis i x-direction be the same as F_b in 4.3.3.2.2 when using S_d given by the first mode and the corresponding percentage of the total mass?

Also, what is the difference between "Sum of val." and "Sum of reactions" in the reactions-table?

# Re: Seismic analysis: parameter lambda

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Again my assumption is that you refer to the value of base shear that is calculated using the static force procedure and you want to have the same value using the dynamic approach. These are two different methods and they will not give the same results.

Checking the results of seismic case you should look at the values of forces and reactions for single modes rather than quadratic combinations. Mind to include all supported nodes filtering the results.

*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**