Stiffing an I-beam column against sideways deflection - Page 2
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  1. #26
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    Feb 2014
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    Re: Stiffing an I-beam column against sideways deflection

    Quote Originally Posted by Kelvin View Post
    Are you sure they need to be stiffened? I mean, a little flex isn't necessarily going to hurt anything. Tuna sticks bend pretty easy, but they also lever up 100kg tuna. Skyscrapers sway in the wind.

    I can see overbuilding things, and I'm guilty of it as often as the next guy, but to match the strength of



    you would probably need i-beams 36" x 24" x 1" weighing many many tons. Are you parking an aircraft carrier on the roof of this thing? These footings seem almost absurdly oversize, unless you're building a bunker capable of withstanding a direct strike with a hydrogen bomb...
    Not exaggerating I have built so things on my property like fence, cow sheds, equipment sheds, corrals, pipe fence, etc that I have easily set over 500 things in concrete probably closer to 1,000. You would be surprised how easy it is to wobble something around that is set in concrete in the ground if you have a long enough lever arm. I have a skid steer with and 18" auger so drilling the holes is no problem. 4.5' deep may be a little overkill but not much. I would say 3' is about the bare minimum. Going an extra 18" for good measure isn't too extreme I don't think.

    We get a lot of wind here. 60-70 mph is fairly common. This is why I went with the larger footings as there are only 4 of them holding this structure which is roughly 30' x 30'. Get the wind blowing right on the bottom of the canopy that could be a huge amount of uplift. The high winds are also why I am concerned about the rocking back and forth. I also plan on having rock put around the columns to match my house. I am worried too much flexing will crack the masonry work.

  2. #27
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    Re: Stiffing an I-beam column against sideways deflection

    Weld an eyelet top and bottom and use 1/4" cable with turnbuckles to create an X
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  3. #28
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    Re: Stiffing an I-beam column against sideways deflection

    Quote Originally Posted by Drilldo View Post
    We get a lot of wind here. 60-70 mph is fairly common. This is why I went with the larger footings as there are only 4 of them holding this structure which is roughly 30' x 30'.
    Gotcha, I was thinking "carport," like one of those 100# aluminum jobbies made out of Pabst cans.

  4. #29
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    Re: Stiffing an I-beam column against sideways deflection

    Quote Originally Posted by snoeproe View Post
    The best way to take the twist flex out of an I beam is to add stiffeners onto the sides. The stiffeners get welded to the undersides if the flanges and to the web. This is standard practice on structural construction when adding loads to beams.
    It's not " a beam" It was an incorrect choice for a column.
    6" sch 40 black iron, filled with concrete and buried a couple feet below slab level is a correct and inexpensive choice for a pole barn.Pour the slab after the roof is on.
    Square tube used when walls or block are part of the build (or future plans)

  5. #30
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    Re: Stiffing an I-beam column against sideways deflection

    In my line of work 99.9 % of the time we were required to have an engineer on site with us. Not necessarily a PE, but some one with an engineering degree.
    When building bridge false work, we had to do this a lot! When the beams were a little too small.
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  6. #31
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    Re: Stiffing an I-beam column against sideways deflection

    Obviously, you need to get the posts wider. Welding to the web isn’t going to help as much as something that extends the flanges.

    A diagonal brace would be most effective and also helps support the load on the horizontal beams - down the side. (A picture of the actual structure would help.) 30ft span seems like a lot for that beam, having a brace that hit 5ft in on both ends would cut the effective span to 20ft. And eliminate front to back movement (if it anchored to the post at the bottom).

    Widening the flanges would help with the front to back wiggle.


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  7. #32
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    Dec 2015
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    Re: Stiffing an I-beam column against sideways deflection

    I would box them in and fill them with concrete.

  8. #33
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    Apr 2018
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    155

    Re: Stiffing an I-beam column against sideways deflection

    Here ya go. The i beam will prolly have trouble with torsion... so this is what ya do to fix it. Name:  Screenshot 2019-05-15 at 7.52.17 PM.png
Views: 267
Size:  27.5 KB

    Also like bonzoo said u really need a column as in 6" or more hollow pipe. Filled with concrete wouldnt hurt, but wouldnt help too much as all the force is concentrated on the exterior, which is y a 2" tube and 1" solid round of the same mass, the tube will be much stronger as the compression strength is proportional to area or radius^2.... Concrete fill will only help if u expect unbalanced loads and torques and torsion which may cause buckling. A beam is the wrong choice, but if u were to use it, you should do what i drew in the picture or at least maybe put some steel plate on both sides so its almost like a square/rectangle which will resemble the tube thing.
    Stiffening the flanges is a waste of time and stiffening the web a little by adding these brace thing as shwon in the pictur every like every x feet will help to make it more ridgid. But to make it the strongest add steel plate cut out and weld to the flanges on both sides to make it almost like a box tube section. Make sure that the columns width and length are 1:1 almost like a square because if its tall and skinny, your wasting that material and it will be less stiff than a 1:1 ratio of the same material.... Like a 2x8 is less strong than a 4x4 in a column scenario even though they have the same area/material amount because its closer to that 1:1 ratio....
    Last edited by n00b; 05-15-2019 at 08:28 PM.
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  9. #34
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    Re: Stiffing an I-beam column against sideways deflection

    Quote Originally Posted by CEP View Post
    In my line of work 99.9 % of the time we were required to have an engineer on site with us. Not necessarily a PE, but some one with an engineering degree.
    When building bridge false work, we had to do this a lot! When the beams were a little too small.
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  10. #35
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    Re: Stiffing an I-beam column against sideways deflection

    incorrect choice of verticals in the first place. All the canopies I see have 3x3 or 4x4 sq. tube for verticals the really big ones have 6x6 sq. . I would say box them in if your not going to replace them. A lot of wasted metal in that structure.

  11. #36
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    Re: Stiffing an I-beam column against sideways deflection

    incorrect choice of verticals in the first place. All the canopies I see have 3x3 or 4x4 sq. tube for verticals the really big ones have 6x6 sq. The one you show is not what I would call really big 4x4 sq would have sufficed. I would say box them in if your not going to replace them.

  12. #37
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    Feb 2014
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    Re: Stiffing an I-beam column against sideways deflection

    Replacing them is out. It is already built. The design is what was recommended by the steel supplier. Right or wrong virtually all larger metal buildings I see around here use I beams for the columns and rafters. The only time I see square tubing or pipe for columns is on small carports or livestock sheds.

    I realize a diagonal x brace either welded solid or cable and turnbuckles would lock it down but I don’t want that on the sides to trip over or hit car doors on.

    It seems I could weld something on the columns to solve the problem. The issue is I am not sure what and I have a half dozen different suggestions from members in this thread with a lot of conflicting advice. Some say adding to the flanges would be best and others say that won’t help and to box it in. Either way it would be about the same amount of material and welding.

    Since the columns are super stiff in the 12” direction I don't see why adding a single additional beam to the columns rotated 90 degrees wouldn’t work, and would be easy to do but that doesn’t seem very popular.

  13. #38
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    Re: Stiffing an I-beam column against sideways deflection

    Try a diagonal brace from the base of the column to even 2ft in on the top. Could be square/round tube or I beam (flat or angle wouldn’t be ideal) and you can just tack it on at one corner and see how much it helps. Relatively to remove if it doesn’t work.

    The basic idea is you have to increase the cross section in the 4in dimension - stiffness is almost exclusively a function of cross section, more than thickness or even material. If you box it, as is, you won’t get nearly as much benefit as using the same 12in wide material to make the flanges wider. By running a diagonal brace your are effectively widening the beam in that direction - plus it seems like it would look better than another I beam scabbed onto the one you already have (personal preference of course). And the diagonal brace would be a lot easier to remove if it wasn’t enough. To test it, you could even figure out a way to clamp something on without any welding to the existing structure.

    If you don’t want to do the diagonal, get the 4in dimension of the beams closer to 12in and it should make a big difference. (Fancy idea: split 12in pipe in half, weld to the flanges on both sides of the I beam. When you’re done = 12x16 oval cross section. Probably stiffen it right up!)


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  14. #39
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    Re: Stiffing an I-beam column against sideways deflection

    Quote Originally Posted by Drilldo View Post
    Replacing them is out. It is already built. The design is what was recommended by the steel supplier. Right or wrong virtually all larger metal buildings I see around here use I beams for the columns and rafters. The only time I see square tubing or pipe for columns is on small carports or livestock sheds.

    I realize a diagonal x brace either welded solid or cable and turnbuckles would lock it down but I don’t want that on the sides to trip over or hit car doors on.

    It seems I could weld something on the columns to solve the problem. The issue is I am not sure what and I have a half dozen different suggestions from members in this thread with a lot of conflicting advice. Some say adding to the flanges would be best and others say that won’t help and to box it in. Either way it would be about the same amount of material and welding.

    Since the columns are super stiff in the 12” direction I don't see why adding a single additional beam to the columns rotated 90 degrees wouldn’t work, and would be easy to do but that doesn’t seem very popular.
    Buildings have walls, your canopy doesn't. Completly different design load. Was it an engineer at your steel supplier or just someone selling steel? I find most sales people know very little about their products. I winter in South Texas . RV canopies are very popular to keep the sun and rain off the rv's. Most in my area are 24x60 and ussually 14ft verticals. They all use square tube for up rights. I have one next to my camper that is 12x48 that covers my patio. It is free standing with 11ft verticals. There are 6, 3"x3" verticals holding the thing up. Now remember there is no snow load in south texas to consider but there is a lot of wind. The wind effects a canopy much different than it effects a building.
    Last edited by thegary; 05-16-2019 at 06:48 AM.

  15. #40
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    Re: Stiffing an I-beam column against sideways deflection

    Boxing it in to make a square tube would be the easiest option imo to maintain open sides, just buy flat bar at the appropriate width and the same thickness as the I beam flange, balance and stitch welds to control distortion. Another option would be to to add gussets that run from the base of the column to the to the top horizontal beam in the weak direction. You'd lose a little of the open wall design but most of the loss would be at the top, could use anything from strap to tube, rod and even wire rope with a turnbuckle - the beams and supports would look like this: |/ \| . Yet Another option to keep relatively open sides is to add another beam or post a 6 inches to foot or so over in the weak direction and make a vertical truss type design. ||X||. doesn't have to be very wide to add lots of strength in the weak direction, you'd lose maybe a a foot max at each corner but would have the hassle of the footing for another post. Good design/engineering lessons to be learned here without the tragedy of a major failure. pole barn type Posts are usually round or square tube for a reason, Most engineered I beam designs are like angle iron/channel designs, the beams are connected in different directions to "box" the structure in, that is they are oriented to reinforce their inherent weak sides, essentially making them a box type (like hollow structural steel ie square tube or round tube) structure rather than channel, i beam, angle. Good luck!
    Last edited by SlowBlues; 05-16-2019 at 08:01 AM.

  16. #41
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    Re: Stiffing an I-beam column against sideways deflection

    Quote Originally Posted by Drilldo View Post
    Replacing them is out. It is already built. The design is what was recommended by the steel supplier. Right or wrong virtually all larger metal buildings I see around here use I beams for the columns and rafters. The only time I see square tubing or pipe for columns is on small carports or livestock sheds.

    I realize a diagonal x brace either welded solid or cable and turnbuckles would lock it down but I don’t want that on the sides to trip over or hit car doors on.

    It seems I could weld something on the columns to solve the problem. The issue is I am not sure what and I have a half dozen different suggestions from members in this thread with a lot of conflicting advice. Some say adding to the flanges would be best and others say that won’t help and to box it in. Either way it would be about the same amount of material and welding.

    Since the columns are super stiff in the 12” direction I don't see why adding a single additional beam to the columns rotated 90 degrees wouldn’t work, and would be easy to do but that doesn’t seem very popular.
    Widening the flange and boxing between the flanges achieves the same effect.
    Do whichever one suits your abilities the best.

  17. #42
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    Re: Stiffing an I-beam column against sideways deflection

    Quote Originally Posted by Drilldo View Post
    Since the columns are super stiff in the 12” direction I don't see why adding a single additional beam to the columns rotated 90 degrees wouldn’t work, and would be easy to do but that doesn’t seem very popular.
    If the cost of them isn't a concern, it would be a very easy solution in my opinion.
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  18. #43
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    Re: Stiffing an I-beam column against sideways deflection

    Scroll down to portal frame. I think this is what you are asking about.

    http://www.bsi-steel.com/03_products...s_bracing.html

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  19. #44
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    Re: Stiffing an I-beam column against sideways deflection

    ^^^

    Looks like a winner...


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  20. #45
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    Re: Stiffing an I-beam column against sideways deflection

    Quote Originally Posted by snoeproe View Post
    The best way to take the twist flex out of an I beam is to add stiffeners onto the sides. The stiffeners get welded to the undersides if the flanges and to the web. This is standard practice on structural construction when adding loads to beams.
    Can you post a picture?

  21. #46
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    Re: Stiffing an I-beam column against sideways deflection

    Quote Originally Posted by ColtonWelds View Post
    Can you post a picture?
    n00b and CEP both have already.
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  22. #47
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    Re: Stiffing an I-beam column against sideways deflection

    Just sister an identical beam, same orientation. You don't need to do all 4 posts, just one end or the other.

  23. #48
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    Re: Stiffing an I-beam column against sideways deflection

    Just box them in. 2-12 nominal welds is likely okay. 1/4" plate is likely adequate.

    Yeah, wide flanges are horrible for weak axis bending, engineers learn that VERY quickly.

    Short of adding X-beacing, this is probably the best/ cheapest option.

    For future projects, tube columns are probably better options.

  24. #49
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    Re: Stiffing an I-beam column against sideways deflection

    Quote Originally Posted by Strutaeng View Post
    Just box them in. 2-12 nominal welds is likely okay. 1/4" plate is likely adequate.

    Yeah, wide flanges are horrible for weak axis bending, engineers learn that VERY quickly.

    Short of adding X-beacing, this is probably the best/ cheapest option.

    For future projects, tube columns are probably better options.
    PM if you need additional information.

  25. #50
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    Mar 2011
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    Re: Stiffing an I-beam column against sideways deflection

    Hi, I"m sure you have this building finished long ago by now.
    But Just wanted to add I have seen I beam strengthened By welding something like
    a 1" x say 3" or 4" wide welded on its edge. " the 1" against post" and welded up the centre of the web.
    I don't think that could ever bend. and would be cheap and easy to do It could be the same width as your flange
    to blend in.

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