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| Still wouldn't work with a 1-1/2" thick web. The shear would be more than that amount of wood could handle if it was loaded to the maximum load the flanges could take.
Carved out of a solid it would have been 14-1/2" high and 5-1/2" wide. Two three inch flanges and one 5-1/2" web in height. Today its usually considered that a laminated beam, like a pole barn pole is better than a solid one because the solid one tends to split as it dries. That's a much smaller problem with 2" lumber dried before its assembled.
Holes in the web at the center line are not much of a problem. Holes at the flange part of the web have serious weakening effects. Holes in the flanges hurt strength a lot too.
Loading a channel like a truck frame requires applying the load to the web with an angle bracket because if you load the top or bottom flange of the channel it twists and its not so strong in twist. To prevent that twist the load has to be beyond the web. It could be applied equally well with a flat slab on top the flange, but the center of the load has to be on the other side of the web from the flange. Usually that's done with an angle bracket to the flange because that leaves the frame height constant where slabs on the flange would be higher.
You can test these concepts with a beam folded up of paper or cardboard, don't need steel and tons of load.
Gerald J. | |
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Square vs. rectangle? Tube bridge physics.
