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bjornhgr
Posts: 69
Registered: ‎09-28-2011
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Seismic analysis: parameter lambda

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12-18-2011 11:57 PM

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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Artur.Kosakowski
Posts: 5,111
Registered: ‎12-17-2010

Re: Seismic analysis: parameter lambda

12-19-2011 12:43 AM in reply to: bjornhgr

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.

 

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Artur Kosakowski
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Valued Contributor
bjornhgr
Posts: 69
Registered: ‎09-28-2011

Re: Seismic analysis: parameter lambda

12-19-2011 06:11 AM in reply to: bjornhgr

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?

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Artur.Kosakowski
Posts: 5,111
Registered: ‎12-17-2010

Re: Seismic analysis: parameter lambda

12-19-2011 06:58 AM in reply to: bjornhgr

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
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