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Thread: Moment of inertia for angle iron?

  1. #1
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    Moment of inertia for angle iron?

    There's an online calculator I'm trying to use to figure out the deflection on 1/8" x 1", 1/8" x 1 1/2" and 1/8" x 2" angle iron for various spans. However, it wants to know what the moment of inertia is before it will do the calculation. I have no idea what that is. I looked online to see if there was a way to calculate that but the formulas given were way over my head. Would anyone here know what that moment of inertia is for the sizes I've given

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    Re: Moment of inertia for angle iron?


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    Re: Moment of inertia for angle iron?

    Quote Originally Posted by WTXBTUMOVER View Post
    Nice WTXB

    According to that the values are:

    1 inch = .022

    1.5 inch = .078

    2 inch = .19


    And the deflection calculator says a 10 foot length of 1 inch angle with a 200 pound load in the center will deflect 10.9 inches

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  6. #4
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    Re: Moment of inertia for angle iron?

    Be real careful when calculating deflections (and strength) of angles under bending. Depending on the axis you are bending about, lateral restraints, and the placement of the load (relative to the shear center of the angle), an angle will experience lateral-torsional buckling way before it will reach the yield strength of the section.
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  8. #5
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    Re: Moment of inertia for angle iron?


    JD1


    Quote Originally Posted by JD1 View Post
    . . . I have no idea . . . way over my head . . .
    Agree - you don't know - whether your posterior
    'is punched or drilled' . . .

    PLS - describe your entire project, so the details
    can be properly eviscerated . . .

    hth


    Opus



    .

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  10. #6
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    Re: Moment of inertia for angle iron?

    I always overbuild . Depending on your use, I find people usually excede what it's rated for. Heavy is usually better.


    Sent from my iPhone using Tapatalk

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  12. #7
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    Re: Moment of inertia for angle iron?

    Thank you all, except for Opus and his fascination with my a**. The project isn't at a critical level, if it were I'd look deeper into the concerns Ingenuity raised. I think I have the info I need now.

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    Re: Moment of inertia for angle iron?

    Quote Originally Posted by ronsii View Post
    Nice WTXB

    According to that the values are:

    1 inch = .022

    1.5 inch = .078

    2 inch = .19


    And the deflection calculator says a 10 foot length of 1 inch angle with a 200 pound load in the center will deflect 10.9 inches
    I assume that if that 200 lb load was supported with not one piece but two, like for a shelf, then the deflection would be half of that - 5.45" instead of 10.9"?

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  16. #9
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    Re: Moment of inertia for angle iron?

    Quote Originally Posted by JD1 View Post
    I assume that if that 200 lb load was supported with not one piece but two, like for a shelf, then the deflection would be half of that - 5.45" instead of 10.9"?

    According to the calcs site...yep... that was also just a 'supported ends' calc not a fixed ends which would add tension to the deflection resistance... and it is a technical number because I think we all know one piece of angle will twist all over the place with 200 pounds loaded in the middle of it 2 inch was a heck of a lot less deflection btw.

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    Re: Moment of inertia for angle iron?

    Quote Originally Posted by BD1 View Post
    I always overbuild . Depending on your use, I find people usually excede what it's rated for. Heavy is usually better.


    Sent from my iPhone using Tapatalk

    Don't say that if front of Sammmy....

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    Re: Moment of inertia for angle iron?

    Thanks ronsii, if the project goes through the angles will be bolted on each end so that helps. Specs are changing so I'm not sure it will go through but at least I know how to deal with it now.

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    Re: Moment of inertia for angle iron?

    Quote Originally Posted by ronsii View Post
    Nice WTXB

    According to that the values are:

    1 inch = .022

    1.5 inch = .078

    2 inch = .19


    And the deflection calculator says a 10 foot length of 1 inch angle with a 200 pound load in the center will deflect 10.9 inches
    I highly doubt a 1" steel angle ten feet long is going to support 200 pounds at the center. Unless you anchor the ends and use it taunt like a piano wire.

    Sincerely,

    William McCormick
    If I wasn't so.....crazy, I wouldn't try to act normal, and you would be afraid.

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  22. #13
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    Re: Moment of inertia for angle iron?

    Quote Originally Posted by William McCormick View Post
    I highly doubt a 1" steel angle ten feet long is going to support 200 pounds at the center. Unless you anchor the ends and use it taunt like a piano wire.

    Sincerely,

    William McCormick
    LOL!!! Yes, I just always like to put extreme values into calculators to see what the results come in at

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    Re: Moment of inertia for angle iron?

    Quote Originally Posted by ronsii View Post
    LOL!!! Yes, I just always like to put extreme values into calculators to see what the results come in at

    I would actually just bend up sheet metal to create the shelf myself maybe 1/16" material with a 2" face 1/2" return, and a two-inch bend on the back as well.

    Or you could do this. This is extremely strong. And you can load it so that it can take a lot of weight.

    Name:  shelfsupport3 - Copy.jpg
Views: 82
Size:  43.9 KB

    Name:  shelfsupport-1.jpg
Views: 80
Size:  100.8 KB


    Sincerely,


    William McCormick
    If I wasn't so.....crazy, I wouldn't try to act normal, and you would be afraid.

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