## Robot Structural Analysis

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# Tau formula

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hi,

i got this design result for one of the beams in my model.

i find it weird since the Vy,Ed value is very small.

can anybody provide the extended calculation for Tau,ty,Ed, and how it comes to that value 1.45 ?

Solved! Go to Solution.

# Re: Tau formula

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Please check the torsion (stress due to torsional moment) in this bar rather than shear.

*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**

# Re: Tau formula

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You were right. It was from the torsional moment. I checked it and i got the 1.45 value.

Thanks.

One more question.

In my attempts to find a solution, I opened the detailed design window.

I set some stiffners, thicked all the verification boxes (web stability at shear, at compression, etc.)

Then I hit the Calculation button and got the results. After that I did some modifications to the stiffners ( increased the thickness ). When i tried the do the calculation again, the mouse cursor changet to "working" but when in changed back to normal i didn't get the results anymore.

Any ideas why?

# Re: Tau formula

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I would need the step by step description of your actions or a movie (plus the model) to run some test and try to investigate the situation you described.

**Artur Kosakowski**

# Re: Tau formula

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I attached a picture with the steps I did (numbered from 1 to 8).

I tried to attach the model too, but it seems the zip file it's too large

# Re: Tau formula

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Is your file saved with or without results? Try to save it under a new name selecting rtd without result and then compress it. In addition copy the spacing of ribs from the field and paste it on the forum so that I can see it in full. Thank you.

**Artur Kosakowski**

# Re: Tau formula

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I couldn't make it smaller. Probably there were results stil in the file and i didn't know how to discard them.

I selected all the structure and used the "Save substructure" button. Hope that's fine.

I set the stiffener distances as it followes: 0.00 ; 3.00 ; 6.00 ; 9.00 ; 12.00

(meter) absolute distances.

the beam is 12 m long

# Re: Tau formula

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I have followed the steps you described but in my case the results are correctly displayed after making changes to the location of the stiffeners and their thickness. Try to close Robot and then load the file again and check if you are able to run the detailed analysis.

*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**

# Re: Tau formula

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That's what i did.

And it worked agan one time, then no more.

I maybe should try reinstalling.

# Re: Tau formula

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Could you make a movie that show exactly all your actions please? I'll try to follow. Perhaps there is something that we do in a different way and the movie will help me to find the reason.

**Artur Kosakowski**