Running FEA with beams

hi guys,

I'm a complete noob in solidworks so sorry if this is a dumb question. I've been trying to run an FEA with a structure i made out of weldments and solidbodies. The solid body is essentially a plate, which is mated onto the weldments. I want to apply a force to that plate and have the bottom of the weldments be the restraint. This is quite easy to do when no weldments are involved, but with it, I have no idea how to proceed. I managed to create an FEA, but I've no idea if its accurate and if I did the right steps. Here's a summary of what I did:
1. set contact sets between weldment frame and plate, set 1 is the weldments that touched the plate, set2 is the face that touches the weldments.
2. calculate joint group
3.Set joint fixtures on the joints of the weldments that touches the floor
4.set force on plate
5. run FEA

this results in an fea with only the solid plate showing any different color, so I'm assuming that the weldments were not affected. Can someone please tell me what I'm doing wrong?
Thanks,