Overturning moment

[MUHANNAD.ABU_ABDO]

Hello everybody ... i'm wondered why overturning moment is zero ? when i calculate seismic force on each floor by using equivalent lateral force 

[t.sautierr]

I think it is because is applied seismic forces and not effort in the structure. Seism induces horizontal forces only (no moment) that induce shear, moment, comp/tract.

[MUHANNAD.ABU_ABDO]

So if there's eccentricity causes torsional moment robot will not take it into account !! is there's way can i find the overturning moment from it or should calculate it manually 

[t.sautierr]

see reaction  and effort in the bars after calculaing the model

[MUHANNAD.ABU_ABDO]

what do you mean by effort ? i don't understand you perfectly 

[t.sautierr]

N, M, V in the bars 

[MUHANNAD.ABU_ABDO]

But i'm talking about shear wall !! not columns 

[t.sautierr]

then look at the effort in your walls ! or post your model.

[MUHANNAD.ABU_ABDO]

i found this problem also .. there's big difference between manual calc. and robot calc .. take a look to these two pics 

[omusafer]

I know this is quite an old post but I seem to be getting zero moments as well. I'd assume it calculates the overturning moments. How do you get the table to show values and how can I check the equation it uses to calculate it? I'm using RSA 2017.

[MUHANNAD.ABU_ABDO]

you can get the table from Analysis >> calculation note, and you can check the results if you want as double check by using manual calculation, you have all the required parameters so it's easy to calculate the base shear value manually and compare it with the one you've got from robot analysis 

[omusafer]

Yes, but my question was not about base shear (I can compare that easily to my hand calculations). I was referring to the bending moment that the output shows as zero. I'd like to know what I should do to make the results output values to the overturning moment which I can use to compare it to my hand calculations.

[Refaat]

Hi

If you want to study the overturning moment in direction e.g (Global – Y) then (the moment about X-axis) should be considered (Mx) while as in this case (My = 0).  The values of both of them are mentioned in stories table. (See capture).

 Therefore, I am not sure about the moment (M-- (Not specified)) which is mentioned in the calculation note. (See capture).

  I look forward to hear from one of official technical team to explain this issue.

Regards

Refaat

[omusafer]

Thank you for your contribution refaat,

While that is unusual for RSA to output something vague like that, I also noticed that the shear values you get per storey in the calculation note does not match the ones that you seem to get when you output the tabular loads for storeys (as shown in your image). Only the 4th storey (156.06kN) match up but not the rest. Seems like RSA is unsure what to output as data...

I too would like to hear Autodesk's official response to this.

[Refaat]

Hi

I would like to draw your attention that the shear values in both 3D graphical model & stories table are represented (cumulative values) whereas the shear values in calculation note are related to each story.

For instance:

V (story 3) = 268.33 – 156.06 = 112.27 KN

However, for the moment values in calculation note still need some clarification from RSA technical support.

Refaat

[Artur.Kosakowski]

 Therefore, I am not sure about the moment (M-- (Not specified)) which is mentioned in the calculation note. (See capture).

  I look forward to hear from one of official technical team to explain this issue.

Regards

Refaat

They are in-plane ones (in XY plane) = horizontal force calculated for the story * defined eccentricity 

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.

[francois.haykal]

would you please advise on how to check the overturning moment ?

how to calculate M0 and how to check it if it's ok or not

thank you

[jureimers]

The answer given does not make any sense what so ever. My and Mx are by nature in plane. Would you elaborate on your answer and clearly explain how to resolve the stated question.

Furthermore how do you get the overturning moment in the individual panels - which eccentricity must you divide by_