photobucket not working nicely for me, but I managed to grab one of your images, the one with the iris-like, pseudo-tangential supports. Picture re-posted here in case others are having trouble accessing it also: Rooster's Design

Don't you think this design would strangle the tree as it grew? The timbers can't open like an iris unless there were no decking, though I suppose you could have floating deck plates that could move past one another...