Yeah there's a sign on the top of the hill past the entrance to "not climb onto arches" - In my 1.5 years here, I've only seen one person climb up on the side, but not on top of broken arch.... I've counted more illegal back country campfires than people going onto the arches.
That thing arch is called "Ribbon Arch" - you would need some serious technical climbing skills to get up to it as it's way up there with no straight forward work arounds.
Great shots!!! Does the park have signs there to not climb on the area in the second photo?? That one looks like it would break so easily and someone could get hurt but more importantly breaking that beam would be a horrible loss for eternity.