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## Robot Structural Analysis

Valued Contributor
Posts: 82
Registered: ‎07-22-2011

# Purlin Design - Rotational Stiffness

492 Views, 5 Replies
12-27-2013 09:00 AM

Hello,

I'm writing this post while testing cold formed purlin design taking advantage of steel sheeting stiffness (Eurocode 3 - EN1993-1-3).

This is an eurocode and robot doubt, taking a look on a random purlin detailed result there is CDA: rotational stiffness of the connection between the sheeting and the purlin. Eurocode expression is: CD,A=C100.kbA.kt.kbR.kA.kbT, where for gravity loads kA has 4 expressions depending on sheeting position and thickness, but all depending from "A: load introduced from sheeting to beam". How is robot calculating this value A?

Best Regards,

RR

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Product Support
Posts: 4,777
Registered: ‎12-17-2010

# Re: Purlin Design - Rotational Stiffness

12-30-2013 06:02 AM in reply to: RRufino

A is assumed as the maximal value allowed by the  the point 10.1.5.2.(5)  = 12 kN/m

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
Posts: 82
Registered: ‎07-22-2011

# Re: Purlin Design - Rotational Stiffness

12-30-2013 07:15 AM in reply to: RRufino

Thanks Artur but in fact, as far as i could understand, using the highest boundary of "A" lead us to optimistic (non-conservative) approach. This is not we expect from design software (if it was a conservative approach, i was ok with it).

If possible please take a look to this issue.

Thanks,

RR

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Product Support
Posts: 4,777
Registered: ‎12-17-2010

# Re: Purlin Design - Rotational Stiffness

12-30-2013 07:36 AM in reply to: RRufino

I have added the request for the manual definition of A value to the wish list.

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
Posts: 82
Registered: ‎07-22-2011

# Re: Purlin Design - Rotational Stiffness

01-03-2014 03:05 AM in reply to: Artur.Kosakowski
Thanks Artur, nice idea.

You can also consider to give a chance to users choose that CDA is determinated by 10.1.5.2 (7), in my opinion this is the way commonly used by structural designers.

Have a nice 2014
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Product Support
Posts: 4,777
Registered: ‎12-17-2010

# Re: Purlin Design - Rotational Stiffness

01-07-2014 07:38 AM in reply to: RRufino

As there are 3 ways of calculating CD,A and two for CD,C I have created the request for the possibility of manual definition of CD (10.1.5.2(1))

Artur Kosakowski
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