Beams look like earthquake reinforcement to avoid a falling upper deck.
Entertainment companies used to park all their stuff on the lower level between T1 and T2 when shooting (TV or movies, not guns!) at LAX. The cast and crew would hang out there on the lower level outside between terminals. I haven't seen them do that in a long time, but I haven't had occasion to look either.
I haven't been in LAX for a long time. I should check this out. Lots of changes, huh? I am going on next flight from PHX-LAX-BOS and return back to PHX via LAX. This will be my first transcons flight.