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Calculating steel round bar's max capacity to support?

  1. Nov 3, 2016 #1
    First off, I am new to this forum.. However I wanted
    To find out if anyone would be able to help me calculate
    How much a steel bar (2 in. In diameter, 5 ft. Lengthwise)
    Would be able to hold up without bending?
  2. jcsd
  3. Nov 3, 2016 #2


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    Gold Member

    Uh ... do you think maybe it might matter what KIND of steel you are talking about? Do you think it might matter where the supports are and where the load is? Could you maybe be a little more vague in your problem statement?
  4. Nov 3, 2016 #3


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    Science Advisor


    Even with no weight on the bar it's still bending under it's own weight.
    Adding additional weight makes it bend more.
    The real question is, how much deflection is acceptable?
  5. Nov 4, 2016 #4
    Sigh. This doesn't have to be hard.

    Specify, specify, specify before asking anything.
    • Sketch the arrangement (horizontal, vertical, something in between) and form a Free Body Diagram.
    • Identify the end conditions (simple, pinned, cantilevered, whatever).
    • Specify the loading (point load, distributed load), specify the material.
    • Find an Engineering-related website or (gasp) perhaps even a Strengths of Materials textbook that provides formulas for beam loading.
    • Find the applicable equation for beam loading.
    • Apply the correct material strength & section moment of inertia values.
    • Those equations will tell you the amount of stress & deflection present in the beam at any point.
    • Use those values to determine if your conditions are suitable.
    The material is elastic and will always deflect under load ("zero"). But "Engineering" not "Science" determines what is an acceptable deflection.
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