Vierendeel Truss Instabilities type 1,2 and 3

[Anonymous]

Morning,

I've put a model together for a Vierendeel Truss. I'm modelling in the truss 'structure type'. I've included cladding to the faces of the truss in order to distribute loads, no panel thicknesses have been assigned. 

Under self-weight only (no loads yet applied), the structure seems to be riddled with Type 1/2/3 Instabilities. I've fiddled around with releases but no luck.

Is anybody able to help me get rid of the instabilities and help me understand why they occur?

Regards,

Sabir

Model Attached.

[Artur.Kosakowski · Accepted solution]

Hi Sabir,

You need to define your model as a frame rather than a truss as you rely on rotational stiffness of the vertical elements to restrain horizontal movements.

Geometry > Structure type > change from 3D truss to 3D frame plus adding UX and UY restrains in supports.

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 · Accepted solution]

Thanks Artur