[Dorothy Wood]

Originally Posted by Teh

I actually hadn't seen that bridge before. it's cool though. Bit bigger than i intended mine to be.

Dorothy - the bank of the river is round in ariel view so the deck sits on a concrete parapet for about 2-3m before it reaches the bank edge. It's also cantilevered at both ends too. The arch is on a pin support meaning it's free to rotate (but won't in, say, the wind because of its own weight) so there is no resultant moment dislodging it from the river bank. Under it's own weight, it takes the sag of the bridge deck (which was small anyway) and keeps the cables tense. Basically no matter what the load, the force tending to dislodge the arch at its base is always zero. It'll rotate around the pin, but never by much, and will never fall over because of the angle it sits at with no load on the bridge. The span is only 30m so the deck itself would be fine without the arch, but it looks nice and stuff.

So there.

okay, thanks for explaining! I was starting to get upset. heh.