Vierendeel Truss Instabilities type 1 and 2

[Anonymous]

Good morning.

I am designing a roof structure with steel members connecting to a Vierendeel truss which runs along the apex. The truss supports 100x100x3 SHS Roof members. These members are pinned to the truss. The roof cover has been modelled as a cladding material with no properties, purely for load distribution. There are linear pin supports running under panels in the middle of the roof to simulate walls.

I am getting instabilities of type 1 and 2 within the truss, in direction Rz and Uy. I have been unable to resolve it by playing around with the releases. 

Any help would be most appreciated!

Rosie

[Artur.Kosakowski]

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]

Hi Artur,

Thank you for responding. This did not actually resolve the instability issues, the problem turned out to be that I had defined the vierendeel truss members as 'truss' members which was incorrect as this meant they could only take axial load when they were also required to take bending. 

Rosie

[Artur.Kosakowski · Accepted solution]

Yes, that would be an alternative to additional bracing for truss bars 

I'm glad you solved this issue.  Good luck with your project.