Cow Creek Bridge
February 29, 2008
Photo taken by Michael Goff in February 2008
BH Photo #117532
When I first came across the Cow Creek Bridge I had a thought or two about classifying the bridge as a Vierendeel Truss. However, after further investigation I decided that this bridge is a pony or through girder bridge and not a Vierendell Truss.
Here is my reasoning. The short definition of a Vierendeel Truss is, a truss where the members are not triangulated but form rectangular openings, and is a frame with fixed joints that are capable of transferring and resisting bending moments.
While at first glance the Cow Creek Bridge may fit this definitions I noticed one key factor that swayed my vote on this one. The Vierendell Truss requires members to be rigidly connected. The Cow Creek Bridge has no individual members, just one giant plate with rather large holes cut into it. Had the bridge had a top chord, bottom chord, and connecting members that were welded or riveted together then this defiantly would be a Vierendell Truss.
Essentially the engineer designed a railroad style plate girder bridge and then cut holes in the girder to provide a more structurally efficient bridge. The reinforced holes and the large vertical stiffeners do give the appearance of a Vierendell Truss, but in my opinion this bridge is a unique plate girder bridge.
Again this is my opinion and reasoning on this subject and would love to hear what others might think, this could be an interesting discussion.
This bridge looks like it could actually be a Vierendeel Truss:
Just a thought though.