Wind Tunnel - Required Data out put

[Anonymous]

Hello,

I would like to extract the following tables so  I can give them back to the wind tunnel specialists to perform my analysis:

1- Mass per floor

2- Moment of inertia of the floor

3- Radius of gyration of the floor

4-Center of mass for coordinates of the floor.

Modal information:

1- The model at each floor in UX, UY , UZ

[Pawel.Pulak]

Some explanations to your questions:

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@Anonymous wrote:

I would like to extract the following tables so  I can give them back to the wind tunnel specialists to perform my analysis:

1- Mass per floor

2- Moment of inertia of the floor

3- Radius of gyration of the floor

4-Center of mass for coordinates of the floor. 

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This parameters are available in the table of stories when stories are defined in the model. Radius of gyration can be calculated from moment of inertia and mass.

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@Anonymous wrote:

Modal information:

1- The model at each floor in UX, UY , UZ

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I assume you mean the modal shapes corresponding to centers of mass of each story.

In this case it is not so simple because Robot reports components of eigenvectors (mode shapes) for nodes of the model and not necessarily for centers of mass. The simplest workaround for it seems defining nodes corresponding to centers of mass of each floor connected to FE mesh. Eigenvector components  displayed for such nodes will give you necessary data. 

Additional note:

Eigenvectors are displayed in Robot without any units because they only describe the shape which can be scaled to any value. The only thing to remember is that rotation components are given as derivatives of translation components (like RY=dZ/dX) so they are also dimensionless.These derivatives correspond to tangents of appropriate angles

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Regards,

[Anonymous]

I'm not sure about the solution for the center of mass:

I assume you mean the modal shapes corresponding to centers of mass of each story.

In this case it is not so simple because Robot reports components of eigenvectors (mode shapes) for nodes of the model and not necessarily for centers of mass. The simplest workaround for it seems defining nodes corresponding to centers of mass of each floor connected to FE mesh. Eigenvector components  displayed for such nodes will give you necessary data. 

cause it should be calculated based on the total displacements of the nodes not a specific point within the floor. is there any other work around .. center of diaphragm displacements or modes??

[Pawel.Pulak]

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@Anonymous wrote:

cause it should be calculated based on the total displacements of the nodes not a specific point within the floor. is there any other work around .. center of diaphragm displacements or modes??

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I suggested some general solution, which can be used also in case of meshed floor panels.

In case of diaphragms it could be even simpler because the calculation node for the center of diaphragm is automatically generated - and its position can be close to CM of story in case of uniform distribution of columns, walls and beams.

Unfortunately it is not possible to display the components of eigenvectors for the calculation nodes - as it is possible to display displacements - see this post.

So even in such case the best workaround seems defining some dummy, very short, weightless bar, connected to this center of diaphragm and to use one of its end nodes as representative for modal shape.

---------------------------------------------
If this post answers your question please click the "ACCEPT AS SOLUTION" button (the button visible when logged to the forum). It will help everyone to find answer more quickly!

Regards,