THIN WALLED SECTION VERIFICATION

[Anonymous]

Hi, support. I followed your tips to create and verify these kind of section and I get to the same point as you do. Which doesn't give me confidence about this verification. I attached the image of the minute 33:41 of the webinar named: How_to_create_and_run_code_verification_of_user_defined__section. The text says: The following parameters of the section THN... used on the calculations are incrrect: Ay, Az Wall thickness of 2 bars is less than 3 mm. The bars will be calculated according to EN 1993-1-1 guidelines. However, it is recommended to analyze thin walled sections according to the EN 1993-1-3 code. For members 2 the program has not performed the analysis of thin walled members according to the EN 1993-1-3. This bars are made of solid sections for which the analyze is made according with the EN 1993-1-1 code. The question may be if these messages are reliable or just bugs. In the first case which will be the procedure to avoid those alerts. Anyhow I'd like to design a complex thin walled section, and this seems not available yet. Am I right? Thanks in advance Julián

[Artur.Kosakowski · Accepted solution]

I assume that you edited a previously defined user section to "convert" it into thin walled one and then you directly used it in your project. The correct steps should be:

1. Open an existing section

2. Edit its parameters

3. Restart Robot (this is needed as the edited parameters are "read" during the start of RSA)

4. Open a file with a model

5. Use the edited section for selected bars of the structure

For your model:

1. Replace the thin walled section with any other e.g. HEA100

2. Delete all unused sections from the sections dialog with scissors button (or just delete the thin walled section label from the list)

3. Save the file under a new name

4. Restart RSA

5. Assign the thin walled section back to the bars you removed it from

6. Calculate model

7. Run code checking

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.

[Anonymous]

Artur things seems to be better but, found an issue on Ax calculation. I did what you said with a AISI CW20x6 section and made a section in mm 200x70x3 In section database I didn't delete any value, I just edited de values I knew like H, B, all E@ and R@, P1_L, VY, VPY, VZ, VPZ. Section type change 45 into 1005, what's the diference? I checked IS_THIN box In code verification RSA mentioned that EC3 couldn't determine the critical bending moment Mcr for a simple symmetric section and used de guidelines for doble symmetric ones. Where I found the issues is in this: 1. Ax is taken from the previous section value (CW20x6) 2. Ay and Az are both well calculated 3. Ix is well calculated 4. Iy and Iz are both taken from de previous section value (CW20x6) 5. of course the Wely and Welz,..... values are wrongly calculated in points 1 and 4 the previous values are even in inches the others are in mm as I decided mm would be the unit for this database other point that surprise me was when I opened both, the original and the edited section, in Section Definition modulus, they appear as a double line graphic. As I read thin walled sections should be simple line drawings. Is this a way to say that they are not thin walled sections? On the other hand, before I wrote you I draw a simple line closed thin walled section. RHS 200X140X3 and I make this analysis: 1. Ax is well calculated 2. Ay and Az are zero even if I introduced their correct values in the section database 3. Ix, Iy, Iz and Wpl... values are well calculated In this case the messages after the code verification are the same I wrote you before. seems there is a disconnection between database and the calculation values. thanks in advance for the answer

[Artur.Kosakowski]

I need the rtd and your section database with this profile to look at. Could you attach them please? Thank you.

[Anonymous]

Artur attached both files. This topic are very important for us in this moment. And another questions. is there some library with thin walled sections? I mean with IS_THIN check box checked? and where it's sections are made with single line drawings? Thanks

[Artur.Kosakowski]

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. And another questions. is there some library with thin walled sections? I mean with IS_THIN check box checked? and where it's sections are made with single line drawings? Thanks

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What matter is a section symbol rather than the check box. Some time ago I posted the document where you can find the names of the thin walled section databases available in RSA. You can access it from http://forums.autodesk.com/autodesk/attachments/autodesk/351/457/2/EC3%20thin%20walled.pdf

The thread where I originally posted it is:

http://forums.autodesk.com/t5/robot-structural-analysis/how-to-create-thin-walled-sections/td-p/3107...

[Anonymous]

Thanks Artur, but the questions in my last post still remain.

[Artur.Kosakowski]

The section databases have to contain solid shapes of profiles including these which are thin walled if this is what you refer to as the last post questions. For the post 3 I need a bit of time to look at the files you sent. 

[Anonymous]

Yes, I refer the number 3 post. Wait for you response Thanks very much I need to Know if this sofware can design this type or elements properly or not.

[Artur.Kosakowski]

RHS 200X140X3 and I make this analysis: 2. Ay and Az are zero even if I introduced their correct values in the section database

As I explained in my previous answer you need to redefine section label as you created it by modification of he existing section without restarting RSA first.

3. Ix, Iy, Iz and Wpl... values are well calculated In this case the messages after the code verification are the same I wrote you before. seems there is a disconnection between database and the calculation values. thanks in advance for the answer

For hollow sections you should treat this message as the informative one. Such sections are considered as class 4 for the reduction of the effective area of profiles.

[Artur.Kosakowski]

AISI CW20x6 section and made a section in mm 200x70x3 In section database I didn't delete any value, I just edited de values I knew like H, B, all E@ and R@, P1_L, VY, VPY, VZ, VPZ.  

I'm assuminng that you refer to CC rather than CW 200x70x3 as Ax for the prior is in your database entered as 0. 

Where I found the issues is in this: 1. Ax is taken from the previous section value (CW20x6) . Iy and Iz are both taken from de previous section value (CW20x6)

I can't see such issues:

5. of course the Wely and Welz,..... values are wrongly calculated

Why do you think so? 

Section type change 45 into 1005, what's the diference?

The prior will not be designed as thin walled.

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.