JR I Beam

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Would 2x4 11g square  tubing stood up hold as much of a load as a 6" Jr I
Reply:Give some more information on what it will be used for, and I'm sure that you can find an answer.  Kind of hard to give a solid answer without knowing more about how it will be used.I'm a Lover, Fighter, Wild horse Rider, and a pretty good welding man......
Reply:Im just curious if a 20ft piece of 2x4 is a structurely strong as the I beam the i beam has a 2" top and bottom with about 1/8 " web and the tube has basically double the side wall just wondering I currently build my docks with I beam that sit on the floats the longest spans are bout 6 ft was thinking of taking 2x4 it would look better I know from using both that the tube doesn't flex side to side as bad as ideal
Reply:No, probably not. Even though they are close to the same over all  weight, the 6" beam has the top and bottom flanges farther from the neutral axis, thus it can carry more load than a shorter member with similar overall dimensions. Taller sections are almost always stronger pound for pound vs shorter sections. It's the same principal that allows trusses to carry such heavy loads, yet be lighter in weight than a beam of similar strength..No government ever voluntarily reduces itself in size. Government programs, once launched, never disappear. Actually, a government bureau is the nearest thing to eternal life we'll ever see on this earth! Ronald Reagan
Reply:What if I went with a say 2x6 tube or to a 3/16 wall on the 2x4
Reply:Seems like you are wanting the look of the tubing so why not just frame the external pieces with tubing and still use I beam for your cross members.  If you are only spanning 6 ft at the longest I don't see why you could not change up your design a bit to make the tubing work.I'm a Lover, Fighter, Wild horse Rider, and a pretty good welding man......
Reply:Hey Dockman... could you just plate in the I beam to give it a finished look??http://www.steeltubeinstitute.org/pd..._table_bro.pdfMillermatic 251Miller Bobcat 225Lincoln 135Victor Oxy/FuelOlder Thermal Dynamics 50 amp (paid $700 with 10 sets of consumables)
Reply:I could but then you add time and expenses not to sound cheap but materials are so haaigh already steel and floation and customers have no complaints a bout the beam thats what most docks here are built of I just would like to have something no one else does and it looks better and a0' 2x4 is about the same price as the beam.
Reply:The principal behind beams is much like that of a lever. If you have a 1' lever, lets say it takes 100lbs applied to the end to lift a weight. You can lift the same weight with a 5' lever and 20 lbs or a 10' lever and 10 lbs. The longer the lever, the less weight is needed.With beams it's much the same way. It's the material that's farthest from the center or neutral axis that makes the difference. Material that's closer to the center is less useful, and material in the very center is almost useless. 2" of steel 1/4" thick 3" from the center will support more than 2" of steel 1/4' thick 2" from the center. The web adds a small amount, but it's really the material in the flanges that gives you the strength in deflection. if you have 2 items that weigh the same and are just as tall, say an I beam and a tube, the I beam will usually win for strength, because more of the material is concentrated at the flanges, not the web. The math to determine just what shape/thickness is stronger is moderately complex. There are all sorts of charts that help an engineer determine just where the material is and how it will effect the strength of the section. It's been quite a few years since I actually had to do the math on these sorts of things and I can't find my charts right now. There's a fine balance between cost savings with material, vs cost savings with fit up. Beam shapes are usually the cheapest / pound for strength. Tube is usually heavier/ more expensive to get the same strength. However tube is usually easier to fit and you make up some of that extra expense by saving on labor. There are a few other down sides to tube to keep in mind as well. Tube sections that are not 100% welded will hold moisture and rust from the inside out. Tube usually fails faster than a beam shape will due to rust. Also keep in mind with something like a dock structure, that if your beam holds water, you can add a substantial amount of weight to the unit, or if it's sealed 100% it may work the opposite way and add buoyancy. The quality of your welds will make a big difference here.If this all sounds complicated, that's because it is. This is why companies hire engineers to work all this sort of stuff out and pay them big bucks to do so. On a small scale it probably doesn't matter much, but if you are doing production, a savings of a few thousand pounds of material can add up to big savings in more than just the material itself, shipping and handling for example. On the other side, is how much faster they can turn things out and save on labor, even if the material is a bit more expensive..No government ever voluntarily reduces itself in size. Government programs, once launched, never disappear. Actually, a government bureau is the nearest thing to eternal life we'll ever see on this earth! Ronald Reagan
Reply:Well with the tube I can easily prefab parts and easier to fab all my docks have been structurally engineered  with the I beam have to weigh it all out and see if its worth it or not
Reply:Personally i think beam is a far superior material to build docks with.   The tube is going to rot from inside and out.    The tube will capture water and moisture and rust from the inside out.We usually don't have to worry about corrosion out here but a good friend and customer of mine bought a used landoll trailer from back east and we ended up replacing 60% of the square tube cross members that looked decent from the outside but had rotted from the inside out. Apparently the new trailers are built with I beam to combat this problem.Vantage 500's LN-25's, VI-400's, cobramatics, Miller migs, synch 350 LX, Powcon inverters, XMT's, 250 Ton Acurrpress 12' brake, 1/4" 10' Atlantic shear,Koikie plasma table W/ esab plasmas. marvel & hyd-mech saws, pirrana & metal muncher punches.
Reply:Yeah the internal rot has been one other hold up for me
Reply:I use tubing on barns.  Even if the strength is the same after bracing, I prefer using tubing as it makes the construction easier (tubes don't roll on you as bad as open shapes).Unless it's a small barn, I use W beam on the main members and tubing for lath.  I use tubing where most people would use C-purlin.Corrosion isn't an issue since everything is in the dry once the barn is completed.Dynasty200DX w/coolmate1MM210MM VintageESAB miniarc161ltsLincoln AC225Victor O/A, Smith AW1ACutmaster 81IR 2475N7.5FPRage3Jancy USA1019" SBAEAD-200LE
Reply:Yeah most of the time these docks never touch the water unless a big wave hits but people are getting in and out of lake on it
Reply:I assure you being that close to the water they will rot from the inside out.Vantage 500's LN-25's, VI-400's, cobramatics, Miller migs, synch 350 LX, Powcon inverters, XMT's, 250 Ton Acurrpress 12' brake, 1/4" 10' Atlantic shear,Koikie plasma table W/ esab plasmas. marvel & hyd-mech saws, pirrana & metal muncher punches.