Torsion steel beam

[Michele100100]

Hello,

I'm designing a steel  structure and I have a problem in torsion with all the C-section beams on the border :

I have loaded structure with loads on cladding, but in the reality I have a metal deck.

Unfortunately I have this verification:

Tau,ty,Ed/(fy/(sqrt(3)*gM0)) > 1

How can I solve? I'm pretty sure that those beams on the border are not going in torsion because of the welded steel deck on top; there is a way to eliminate this verification or block beams to go in torsion with some releases? 

Those beam are already full fixed between them.

Thanks.

[Simau]

@Michele100100 

Try this:

Split bars on borders and add a support at these created nodes

[Michele100100]

Hello,

Thanks for the advise, but I tried and still have bar in torsion.

attached the model if you can have a look, bar/beam example is n.181.

Thanks

[Krzysztof_Wasik]

Hi @Michele100100 

In case 3 you have defined torsional moments on side beams. 

[Simau]

@Michele100100 

I divided all UPN 100 in individual members

I set them as CL type

All ratios are < 1

Model attached

[Simau]

I forgot to say that i set  the claddings as one way Y

[Michele100100]

Hello,
it was because in that location I have handrails calculated by hands.

[Michele100100]

hello,

I can't see your model because I have 2020 RSA Version.

Could you save in 2020? thanks

[Krzysztof_Wasik]

Hi @Michele100100 

If you are applying torsion moment directly to edge beams you cannot expect zero torsion in those members.

If you assume that that torsion will be transferred by plate welded to beams (and plate is not simulated as structural element in the model) remove torsion loads.

[Michele100100]

ok,

This is the detail:

In my idea UPN100 can't be in torsion because of the deck. Taking off the torsional load it is correct even for this case? Thanks

[Krzysztof_Wasik]

Hi @Michele100100 

If UPN100 cant't be in torsion (according to your simulation idea) do not apply torsion to them.

[Michele100100]

Thanks

[Simau]

@Michele100100 

Sorry, Robot 2020 is no longer installed here.

Just follow the steps discribed in messages 5 and 6 and you'll get the model as i modifieded it.

No problems even if torsion is added at UPN 100.

[Michele100100]

OK, thanks,
I will try how you advise.!