Purlin releases and deformations

[mark.martin.se]

Hi,...


...I'm working lately on a workshop project, 40m wide, 150m long, 17m height. It's a classic rigid steel frame construction.
The problem as you can see in the attached pictures is the excessive deformation in the first and last frame along the local y axes. As you can also see from the attached picture there are „xxxfff“ releases of purlins and wind braces (simply supported, just like I want it). (the first two pictures)

The problem seams to vanish when I change the adjacent purlins releases to „xxxxxx“. Then the deformations become acceptable. (the last two pictures)

What am I doing wrong???

It's impossible and illogical to have such deformations just on the first and last frame???

Any help would be highly appreciated!


Regards!

[lucis29]

I cant see any difference between pictures 2 and 3.

[mark.martin.se]

OK! I'll try to attach some zoom in screen shots!

The first screen shot is the model with excessive deformations, around 350mm, which is really odd! There are "xxxfff" releases (simply supported purlin and bracing)!

The second screen shot is showing "xxxfff" bracing release and "xxxxx" purlin release! (The deformations in this model are expected to be around 30-35mm)