How to offset my lines - please, need your help. (need 3D Bearers)

hi Guys,
how can i offset the lines to get 3D beam's. i tried all offset thinks i know, line offset, i tried moving points. But nothing works correct.

I've been sitting here for hours and get nothing, 

the whole project has to be finished in 7 weeks, I had all the bearers ready.

But my professor had a new idea, since friday, I am sitting on what I have so far.......

But at the moment I fail

I hope someone knows a way, thanks you for reading, thinking and helping!

The files are attached

The end product should look like the second picture,