Odd, I don't remember those particular lift pieces going in at USH... However, they could have been easily missed because the lift installation happened after most of the rood was put in. I think those pieces will just act as a guide track for the lift. There is a square vertical truss of sorts that we should see installed soon. I'm pretty sure that will take the main load of the elevators.
EDIT: They're already installing the second floor!?!?!