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King Post Bridge
The
simplest type of truss bridge is called a "King Post" bridge.
A King Post bridge, much like a cantilever bridge, has compression
and tension members, but in a slightly different arrangement.
Let me show you.
The two green poles are in compression, because when
you put weight on a King Post bridge, they may
buckle. The
bottom two red members are under tension, because when you put weight
on a King Post bridge, they may tear.
Truss Bridge
The nice
thing about a truss bridge is that you can keep repeating the simple
King Post triangle design over and over again, making the bridge any length you
want.
Queen Post Bridge
But we
did not build a King Post bridge. We started out with a truss
bridge that looked much like the above bridge. Then, we realized
that the trusses weighed too much, so we took them out. And
after a few trys, we ended up with a bridge that looks like
this.
… and
then, we found out that there is a name for this type of bridge. We
had re-invented what is called a "Queen Post" bridge !
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