Net overturning moment of the building due to horizontal load

[mustafa-hesenow]

Hi all.

Is there any possibilty to show the net overturing moment in th reaction table without moving the building to be 0 0 0 coordintates matched with the building  center of gravity .

Thanks 

[StefanoPasquini6790]

Hi,

If you mean the seismic action (forces and moment) please go to "diagram for building" command, under the results tool. Obviously, to view this results you have to define the stories in your model.

Gor global geometrical property of your model, please read the detailed report.

Greetings

[mustafa-hesenow]

Hi,

But this one gives the net overturning moment for eacch floor in around the center of gravity of each floor . I asking the overall net overturning moment under each laod case on the base level of the whole building .

thanks

[Artur.Kosakowski]

There is no automatically generated output for such value.

[StefanoPasquini6790]

Well, if you really need you can make by your own an API, or a simpliest Octopus spreadsheet where you read the reaction of the base restraints and the coordinates of the restrained nodes, then you can compose this reactions to calculate the global actions, including your required overturning net moment.

Only a little bit of formulas in Excel , good luck).

Greetings

[mustafa-hesenow]

Thanks Artur.

But i realy think that tme moment the one calculated in the sum of reactions should be the net moment not the soum of moment around the global axsis X or Y.

[mustafa-hesenow]

Dear Stefano,
I know it can be easy done by API pr Excel sheet . The issue the one i am asking about that the total moment shown in sum of reactions it doesn't mean anything during evaluation of the structure that's why I believe that this moment must be replaced by the net moment .
Thanks 🙂

[Artur.Kosakowski]

But i realy think that tme moment the one calculated in the sum of reactions should be the net moment not the soum of moment around the global axsis X or Y.

This part is for checking the correctness of the obtained solution and the way it is done is IMHO right.

My understanding is that what you actually  need is to calculate the applied loads * their distances from the indicated rotation axis vs. values of reactions * their distances to the same axis. This is as already suggested possible outside Robot  e.g. in Excel. 

[mustafa-hesenow]

Dear Artur,

Its really should be like that the net one not the once around the global x and y axis . just take a look at the attached picture you will notice that it even under the self weight or vertical load u will have very huge moment on the sum of reactions if the building coordinates are far from the global coordinates which we always face this issues when the building imported from the Revit .

That's why i am suggesting to correct it .

[Artur.Kosakowski]

What would you do if you want to calculate 4 separate structures as one model? 

[mustafa-hesenow]

Hi Artur ,

 I think this issue needs to be fixed in this powerful software and to be generated automatically and shown in the sum of reaction instead of calculating it around the global axis.

Thanks.

[Pawel.Pulak · Accepted solution]

Hi Mustafa,

calculating the sums of moments according to any other references than (0; 0; 0) is somehow arbitrary because it can be 1/ or the geometrical center, 2/ or the center of mass considering only the selfweight of the structure, 3/ or the center of mass considering all dead loads, or  ...

Moreover it would be necessary to display somewhere these coordinates - sums of moments without information about these coordinates would be useless. Of course these coordinates (at least some of them like 1/ or 2/) can be found in the calculation note or in the table of stories but it would result in the dispersal of necessary data.

Giving the sums of moments always referenced to the origin of the coordinate system (0; 0; 0) such doubts are avoided.

Moreover it is always possible to convert these sums of moments to any other references using simple formulas.

Assuming that:

• the original "Sum of reac." for forces and moments are FX, FY, FZ, MX, MY, MZ respectively
• the new references have Xc, Yc, Zc coordinates
• the reaction moments converted to the new coordinates are MXc, MYc, MZc

the formulas for the converted reaction moments are:

MXc = MX - FZ*Yc + FY*Zc

MYc = MY + FZ*Xc - FX*Zc

MZc = MZ + FX*Yc - FY*Xc

I hope it will be useful.

---------------------------------------------
If this post answers your question please click the "Accept as Solution" button. It will help everyone to find answer more quickly!

Regards,