Abacus - constraining a wing box

[drspoktor]

Hello.

I'm new to Abacus, but I really like it.

I'm trying to model the stresses in the wing box imported from CATIA V5 (

http://imgur.com/WJptbul),

but I fail to properly constrain the system so I end up with something like this:

http://imgur.com/V6KdOiz

What am i missing?

In the actual setup the wing box is clamped at the root and loaded at the tip with a tip clamp. In the model few stringers are missing, those will be added later.

Thanks for your help