The beams that constituted the walls of the Mishkan seem to be free standing. They did have rings at the top to hold them to each other and there was the 2 outer bars and one inner bar that also acted to strengthen the walls, however, with the weight of the roof coverings (or maybe even without them) it seems hard to imagine how all those beams remained upright and didn't lean in or collapse onto each other. If one imagines that there may have been ropes on the edges of the coverings holding them in place that would put even more stress on the top of the beams encouraging them to lean or collapse inward.
The same questions applies to the five beams at the front entrance on the east side (in particular the three inner ones) as they were free standing and held a curtain on them. Also the four beams separating the Kodesh from the Kodesh Hakodoshim (in particular the two inner ones). How did those remain balanced when supporting the weight of the curtain on one side?
There are two suggestions that I can make (aside from saying that it was miraculous) although neither are mentioned in the Torah.
The beams were held up both on the outside and inside of the Mishkan with ropes. However, there doesn't seem to be any mention of this in the Torah.
There were beams running along the top of the Mishkan from north/south. Also not mentioned in the Torah.
(There were ropes to hold up the outer wall of the courtyard of the Mishkan and I think there were ropes on the outside of the coverings of the Mishkan itself.)
Does anyone have any other solutions to this problem?