Large torsional moment using compound I sections.

[YANKEES619267333]

Hi all,

The compound box section are made of UC305x406x340, which is the main beam. There are continuous  secondary beams on top of the compound box section, imposing load onto it.  I spotted a torsional moment of 200kNm. 

For the same set of model, when i change it to UB sections (any size), the torsion will drop to a value of 15 kNm sth. 

I also tried to define the compound section as parametric box sections, or modifying UC's torsional stiffness, still see a value of 200 kNm. Anybody knows why?

Thanks!

[Rafacascudo]

Zip and attach the model if possible