Strength of rectangular tubing.

DFZ · Jun 13, 2014

Working on building a flat bed deck for a 10 ton wagon gear we have and we wanted to use steel beams instead of wood that will rot.

Does anybody know of a website that compares strength of different common steel shapes? Maybe with load capacity between centers easy for a lay-person to use not an engineer.

Or how do you think 6x2x.250 (12.20 #/foot) steel rectangular tubing would compare with 8x2x.188 (11.5 #/foot) tubing or the standard 4x8 wooden beam that we have used in the past. Being a Farmer not an engineer we have always relied on the motto in the past "If in doubt, Build it Stout!"

Thanks for any advice.

Formerly PaMike · Jun 13, 2014

I don"t have any of my info with me, but I have it at work. Shoot me an email with the info and I can look it up on Monday.
I assume the steel tubing would be stood up the tall way? How far apart are the front and rear supports? How much weight on each one?

LAA · Jun 13, 2014

Both of the rectangular tubing sizes you mention are very strong and would do the job if properly tied to gether but channel iron will do the job just as well and be a lot cheaper and is much easier to work with from the standpoint of joining/welding.

MarkB_MI · Jun 14, 2014

I'm not a civi engineer, but I know that the "area moment of inertia" is used to calculate the strength of beams. Basically, the further you can move the cross-sectional area from the bending axis, the stiffer a beam will be. That's why hollow tubing is stiffer for its weight than solid round stock, and why an I-beam is stiffer in one axis than the other.

Here's a site that allows you to calculate the area moments for common cross-sections. Now if you want to compare different materials, you need to know the various properties (e.g. modulus of elasticity) for those materials.
area moment calculator

WESnIL · Jun 14, 2014

My memory says that the strength is proportional to the square of the dimension. So 6 squared is 36 while 8 squared is 64. That means one is about twice as strong as the other when used in the vertical position. This needs to be adjusted downward for the thinner wall on the 8 inch material. I know this same principle works good when dealing with wood for practical purposes. Hope this helps.

Harold Hubbard · Jun 14, 2014

I vote for channel iron. Cheaper, easier to cut and weld IMO, all open for painting. Steel does not rot, but it does rust. If you live anywhere where it rains or is at all humid, you need something without hidden spots for hay/chaff to build up and hold moisture, causing rust and rot.

Anonymous-0 · Jun 14, 2014

I don't know what these guys are thinking that channel is easier to work with than tubing? Channel has to be notched to fit inside itself for cross members. Tubing can be cut straight for cross members. I have a 14,000 GVW trailer. It is made with 6"x2"x.188 wall tubing. I looked at channel trailers and then talked to a custom trailer shop that used tubing. He suggested jumping on one corner of a trailer made with channel and then doing the same thing on a trailer made with tubing. The channel trailer would flex while the tubing trailer didn't move. It turned out that the owner of the trailer shop was interested in my welder at the time cause he was expanding and I traded it and for the trailer and some money to boot. He then tacked it together in his jig and let me build it myself how I wanted it. I've never regretted the decision to go with tubing. There are small holes drilled in the bottom corners of the tubing so that any water that gets in from the deck bolts, etc. will drain. For 10 tons, I think I'd go with the 8" tubing. A little lighter and the 8" height will have more load capacity than the 6".

Strength of rectangular tubing.

DFZ

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Formerly PaMike

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LAA

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MarkB_MI

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WESnIL

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Harold Hubbard

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Anonymous-0

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