Robot Structural Analysis

## Robot Structural Analysis

Contributor
Posts: 15
Registered: ‎08-07-2012
Message 1 of 6 (240 Views)

# Openings in stability core

240 Views, 5 Replies
11-13-2012 02:26 AM

Hello All

I am trying to model a shear wall panel for stability and checking concentration of stresses at the corners.

Any chance of some tips on how to interpret results from ROBOT?

Also, are you aware of any information (guidance, examples) available online?

I think I understand how to extrapolate max compression/tension forces but I am not too sure about shear (for examples in coupling beams above openings). Should I be looking at max values of 5N/mm2 (based on BS) and hope to design shear links to cope for values above vc?

Thanks

Roberto

Product Support
Posts: 424
Registered: ‎06-23-2008
Message 2 of 6 (235 Views)

# Re: Openings in stability core

11-13-2012 03:59 AM in reply to: robmirgga

Hello,

If you define coupling beams over onenings as separate panels (as in your screen captures) then it is possible to obtain total shear, normal force or in-plane moment in edge and centoid cuts of rectangular panels in Results>Advanced>Reduced Results for Panels

http://docs.autodesk.com/RSA/2013/ENU/filesROBOT/GUID-003921A4-A845-4E06-808F-BC0CFF8A2FDE.htm

http://docs.autodesk.com/RSA/2013/ENU/filesROBOT/GUID-3936FDA3-5DFD-4F31-B16A-F0208A451282.htm

In case of more complex shapes of walls (with cavities etc) analogous results can be obtained using Results>Panel Cuts.

Here in-plane shear can be obtained as "integral value" for NXY shear force, normal force can be obtained as "integral value" for NXX horizontal membrane force and in-plane moment can be obtained as "Reduced moment" for NXX horizontal membrane force. Some further explanations and scren captures corresponding to it are given below.

Shear can be obtained as Integral Value for NXY – it means NXY integrated along the length of the cut – that is why the unit is (kN/m)*m = kN:

As concerns the in-plane moment it can be obtained from horizontal membrane force NXX integrating the product of this value and corresponding distance about the center of the cut. It can be obtained as reduced moment about Y axis:

Of course when defining cuts its is necessary to define them and to open in new window to avoid display (and integration) through whole structure.

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Regards,

Pawel Pulak
Contributor
Posts: 15
Registered: ‎08-07-2012
Message 3 of 6 (229 Views)

# Re: Openings in stability core

11-13-2012 04:50 AM in reply to: pp2008

Pawel

Thanks for taking time to create example

I have tried to follow but could do with a check..

I have attached a screen shot for what I think is the total shear at the coupler interface - however I cant get the clear diagrams as shown in yours.

If I could email reduced model to check whether I am in right direction?

Regards

Roberto

Product Support
Posts: 424
Registered: ‎06-23-2008
Message 4 of 6 (224 Views)

# Re: Openings in stability core

11-13-2012 05:46 AM in reply to: robmirgga

Roberto,

shear force can be obtained as an integral of NXY, where NXY is in-plane shear force  in some coordinate system and cut is defined along the XX or YY direction of this coordinate system.

In your case you have displayed N(1-2) which is a maximum in-plane shear force which is "coordinate system independent" - i.e. in each point of panel it can be in different direction because it is related to principal directions of 2D state of stresses. That is why integral of this value in general case has no physical meaning.

If you want to send your model no problem. To reduce the size please use "Save as" to different name and without results. Then compress to ZIP.

Regards,

Pawel Pulak
Contributor
Posts: 15
Registered: ‎08-07-2012
Message 5 of 6 (220 Views)

# Re: Openings in stability core

11-13-2012 06:19 AM in reply to: pp2008

Thanks Pawel

Much clearer, however I still don't think I can locate NXX option

Thanks!

Roberto

In screen shot below I have taken "membrane force - N" from the "complex" tab

Product Support
Posts: 424
Registered: ‎06-23-2008
Message 6 of 6 (211 Views)

# Re: Openings in stability core

11-13-2012 08:04 AM in reply to: robmirgga

Hi Roberto,

below the screen capture from your model showing shear from both reduced results for panel and from diagrams of NXY on cuts.

Of course it is recommended to use finer regular mapped mesh to improve precision - see attached modif.ication of your model.

---------------------------------------------

Regards,

Pawel Pulak

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