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Thread: Section Modulus Help

  1. #1

    Section Modulus Help

    I have two beams I need help with calculating the section modulus: the first is a "C" shape channel, 16" tall, 4" across the flange, and 3" return, the material thickness is .250; the second is a fabricated beam using standard structural tubing 5 x 3 x .188 on the upper and lower components, the 5" leg being the vertical dimension top and bottom, the distance between the upper and lower beam is 18". Thank you, Paul

  2. #2
    Thanks Kelly, I checked it out and my calculation skills are long gone. What would help is an example of the calculations that I need to go through. I understand enough to put in the right numbers. Thank you, Paul

  3. #3
    Lead Engineer Cake of Doom's Avatar
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    Are you looking for worked examples?

  4. #4
    Yes, I am looking for either how to calculate exactly what I am working with or an example that I can use to then calculate what I am working with. Thank you

  5. #5

  6. #6
    Associate Engineer
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    Paul,

    For the C channel piece, here's a Wikipedia entry that has a quick formula:

    http://en.wikipedia.org/wiki/Section_modulus

    For your I beam made from plate stock and tubing, look for an example using built up sections and the parallel axis theorem. You need to calculate the area, centroid and moment of inertia for the tubing and the plate individually. Since you have a symmetrical section, your centroid will be at the center. Then make a table of each of the properties to solve I+Ad^2. Divide that sum by the half the overall height of your beam and you'll have the section modulus.

    Kyle

  7. #7
    Associate Engineer
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    Here is a link for calculating the moment of inertia for a square tube:

    http://www.engineersedge.com/calcula...are_case_4.htm

    Kyle

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