Actually, those beams are made that way by cutting the web out of long plate, then adding the top and bottom flanges. They're called fabricated beams.

chaikwa

 

I realy didn't have a clue about this, but figured it would start a good discussion......

 

I think the strongest shape, at least as far as this board is concerned, is Scotty.

chaikwa.

 

Not necessarily. It depends on how and where the load is applied. Take a ball for example and sit on it. It deformes very easily. Now take an egg shaped object and sit on the pointy end. Does it deform? Take that same ball and apply massive air pressure from inside and it stays the same shape. (overlooking expansion here) Now take some other shape, let's say a square tube of the same wall thickness as the ball and fill it with the same massive amount of air. It will deform. I could give other examples, but hopefully you get the idea.
For the purpose of answering the original question, the shape of the structural member is important, but even more important is how the loads are applied to said member. For example, take a length of channel. If that channel is web side vertical or web side horizontal, the bending loads will vary tremendously. The same idea applies to angle iron; place one leg vertical or at an angle of 45 degrees and everything changes.

 

Thanks for posting that. I think I was confusing my Aerodynamics classes (the "parabolic" reference) with my engineering classes. It's hard for a Poli Sci guy to keep that all straight

 

That's some serious funny right there.

 

bending stresses are in the flanges and shear stresses are in the web. shear cant be ignored for a trailer.

*edit: i'd go c channel and maybe some S channels in there (wide or standard depending on load)

also, check this out as it will would give you a good heads up...

volume 1

volume 2