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Valued Contributor
jo2ny
Posts: 82
Registered: ‎02-07-2012
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Custom sections

934 Views, 4 Replies
02-14-2012 04:22 AM

Hello,

i got a little stuck when defining some custom thin-walled sections. Here's the thing:

I have a rectangular steel container made of: a deck (rectangular with 4 perimetral beams and other secondary beams), 4 columns(poles) and a roof structure. It loocks like a rectangular box.

 

The columns have the section (INC1) I attached in picture 1. It's a thin-walled section made of 3 contours (thickness 6mm).

I defined it as "thin-walled", saved it, used it in the model, run the calculation, and then the steel design.

I got the error: "Calculations have not been performed for members (157 157 .... ) due to lack of some section parameters."


I opened de section database and saw that there were parameters missing - see picture 2.

I manualy calculated Ay and Az, and typed them in the database, saved, and rerun the model.

At steel design i got another error : The following paramaters of the section INC1 are incorrect : Ay,Az.

1) How to solve the problem? 


2) Another question: What if I define the same section as a solid, and for the bars assigned with this section i go to Members definition and thick the box called  "Thin-walled sections"?What's the deference?

 

3) When i save or ask for a section properties (this type: complicated 3 contour whin-walled section) it takes veeeery long time for the program to do the job.

Is there any way of shortening the time  at dispense of some precision?

 

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Artur.Kosakowski
Posts: 5,115
Registered: ‎12-17-2010

Re: Custom sections

02-14-2012 04:57 AM in reply to: jo2ny

Please refer to this topic on the Robot forum:
http://forums.autodesk.com/t5/Autodesk-Robot-Structural/How-to-create-thin-walled-sections/td-p/3107...

The steel design module is not capable of running verification of all kinds of thin walled shapes but is limited to the types of sections that you can find in the pdf file attached to the message 11 in this topic.

 

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
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Valued Contributor
jo2ny
Posts: 82
Registered: ‎02-07-2012

Re: Custom sections

02-14-2012 05:49 AM in reply to: Artur.Kosakowski

I read the other post. 

To be clear, you said that : Currently such sections are not supported for code checking however they can be still used for static analysis of the model.

 

This includes my 3 contour weird section, or only the ones from the families of the supported shape types

Because if this section is not correctly defined => no correct stiffness => no correct displacements for other members.

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Product Support
Artur.Kosakowski
Posts: 5,115
Registered: ‎12-17-2010

Re: Custom sections

02-14-2012 05:58 AM in reply to: jo2ny

For the section intended to to be used in the static analysis I would model it as a solid one in the Section Builder and calculate its properties. Then I would save it in the section database. As for this kind of section the value of IX calculated for a solid section type may be inaccurate I would enter it shape as thin walled and calculate the value of IX in the Section Builder module again. Then I would edit the section in the database and replace the IX calculated for the solid section with the thin walled one.

 

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
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Valued Contributor
jo2ny
Posts: 82
Registered: ‎02-07-2012

Re: Custom sections

02-14-2012 06:39 AM in reply to: Artur.Kosakowski

Ok, i've done both sections calculations. The values are similar.

I will use your recomandation.

 

Thank you for assistance, it was a realy painfull problem.

 

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