Purlin Design - Rotational Stiffness

[RRufino]

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?

Thanks in advance,

Best Regards,

RR

[Artur.Kosakowski]

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.

[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

[Artur.Kosakowski]

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.

[RRufino]

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 😉

[Artur.Kosakowski]

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))