Channel; up or down?

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When using channel for support is it stronger with the load applied to the open side or the solid side? I cannot put it like this "]" in this application, it needs to lay flat.Miller Challenger 172Miller Thunderbolt AC/DC 225/150Miller Maxstar 150 STLVictor 100CVictor JourneymanOxweld OAHarris O/ASmith O/A little torchNo, that's not my car.
Reply:Either way, because you will only be using the flange.Welding everything, from the crack of dawn to a broken heart.
Reply:Originally Posted by CapozzoliEither way, because you will only be using the flange.
Reply:Than why use channel and not tubing?There are no problems. There are only solutions. It's your duty to determine the right one.Hobart Handler 210Airco 225 Amp MSM Stinger
Reply:Tubing would be be my choice, but if you must use channel it will depend on the loading. eg: if there is a downward load at the ends and it's supported in the center then have the flanges facing up, if it is supported on the ends and the load is in the center have the flanges facing down.See what I mean? The open flanges will resist stretch but not compression.This is what rlitman was referring to.Last edited by NVW; 02-01-2012 at 08:40 PM.Leo
Reply:Originally Posted by rlitmanThat's not true.  Try to flex a tape measure, and you'll understand the difference.
Reply:I've built forks for CUT loader buckets w/ 4" channel and 1/8"x4" flat welded to the flanges to form a box and they've held up pretty good. As long as you have something to weld the flanges to I think it would work pretty good. Don't know what you're building. Care to elaborate?                                                   MikeOl' Stonebreaker  "Experience is the name everyone gives to their mistakes"Hobart G-213 portableMiller 175 migMiller thunderbolt ac/dc stick Victor O/A setupMakita chop saw
Reply:I am building a lumber storage rack to fit on my garage ceiling above the door. I only have about 8" of clearance when the door is up, so I chose channel to keep the profile low. The rack will be 7' wide x 8' deep with channel at each end and one across the middle, and expanded metal for a "floor" I will weld plates to the uprights and drill them for lag screws. I will put uprights at about 4' in so I can store 4x8 sheets on one side and the other side will be for 2x4s. There will be a total of 9 upright "legs" bolted to the ceiling joists. My channel is 1.5" X 3/4" X 1/8". There will not be much weight, a couple sheets of plywood aand a dozen 2x4s is all I ever keep around. I also keep a supply of 4x8 sheets of cardboard for when we work on houses with newly finished floors. In other words, I am building a rack out of $150 worth of materials to store $50 worth of materials.The ceiling space above a garage door is usually wasted, I figure why not use it instead of having lumber, which I rarely use, leaning up against the walls and getting in my way.Miller Challenger 172Miller Thunderbolt AC/DC 225/150Miller Maxstar 150 STLVictor 100CVictor JourneymanOxweld OAHarris O/ASmith O/A little torchNo, that's not my car.
Reply:The flanges are stronger in tension over compression, it takes a lot more to stretch the flange than it does to compress it and make it buckle.
Reply:Originally Posted by ironmangqThe flanges are stronger in tension over compression, it takes a lot more to stretch the flange than it does to compress it and make it buckle.
Reply:Is it floor joists or trusses that this is being hung from? If it's floor joists, are they solid beams or I beam?There are no problems. There are only solutions. It's your duty to determine the right one.Hobart Handler 210Airco 225 Amp MSM Stinger
Reply:Makes perfect sense. Which is why there is I beams.  Just move the web to the center of the flanges and then it is equally strong laterally. Which for me raises a question. What advantages are there to using channel instead of an I beam? Seems they would be obsolete.Welding everything, from the crack of dawn to a broken heart.
Reply:Originally Posted by ThorsHammerIs it floor joists or trusses that this is being hung from? If it's floor joists, are they solid beams or I beam?
Reply:It really depends how you mount the ends.If you weld the ends to something solid, the top side near the ends will be under tension and the bottom side will be under compression.  As you move to the middle of the beam its vice versa.To think about this another way.   Place one beam vertical, now weld a second to the first in a horizontal direction.  Put weight on the end of the 2nd beam and the top of the beam is stretch and the bottom is compressed.If you just layed the beam accross two .. say saw horses, then the forces would be reversed.  If you welded both ends you would have a combination.As for which way to weld it.  It doesn't make any difference.  The differences one way vs. another are small.  The tips of the C-channel will have the most stress on them.  You might want to protect them from a nick etc. if you are really pushing it.Con Fuse!Miller Dynasty 350Millermatic 350P-Spoolmatic 30AMiller Multimatic 200Hypertherm PowerMax 1000G3Miller Maxstar 200DX
Reply:i believe oif you look in a steel  construction manual (aisc) you will find that there are no ratings for channel in the configuration you  want..so no engineer will use it that waytubing is a different story..that said, i have racks in my garage like you are wanting that are made of 2" pine  saplings...Last edited by weldbead; 02-03-2012 at 06:56 AM.
Reply:Originally Posted by weldbeadi believe oif you look in a steel  construction manual (aisc) you will find that there are no ratings for channel in the configuration you  want..so no engineer will use it that waytubing is a different story..that said, i have racks in my garage like you are wanting that are made of 2" pine  saplings...
Reply:What size channel are you using?
Reply:Originally Posted by con_fuse9If you look at a metal book, they list 'I' (moment of Inertia) for the beam along that bend axis.  In my case I have a very old mechanics of materials book and it's in the appendix.
Reply:Originally Posted by ar15is223What size channel are you using?
Reply:Originally Posted by bigbIn other words, I am building a rack out of $150 worth of materials to store $50 worth of materials.The ceiling space above a garage door is usually wasted, I figure why not use it instead of having lumber, which I rarely use, leaning up against the walls and getting in my way.
Reply:I'm pretty sure there is a slight difference due to the distance that the load is from the neutral axis of the channel. It won't be much if there is any. I'll look in one of my books and give my opinion on monday.. I'm thinking that with the u upside down with the load on the bottom of the u pushing towards the oppen part there will be less deflection but I don't remember the equations for that off the top of my head lol