Any Mechanical Engineers willing to a solve a math problem?

Discussion in 'General Technical Questions and Answers' started by WA7F, Jul 12, 2019.

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  1. WA7F

    WA7F Premium Subscriber QRZ Page

    I have a question is not ham related but solving it will help me spend me more time with ham related stuff. So in a way it’s remotely amateur radio related. :)

    I’m trying to dial in my pole barn/shop at the new QTH. To make room for a electronics workshop and a future secondary shack, I need to free up some space so there is still an area for larger projects. That means hanging stuff overhead but, I don’t want to add any loading to the rafters. During a wet winter I think they could easily become stressed with heavy snowfall.

    Here’s the question; with a 24’ span of 4.171” x 8” (s8 x 23) steel I-beam that is supported at each end, approximately how much weight can it safely support in the center of the I-beam? Evenly distributed weight capacity would be useful too if that’s an easy calculation. Any advice will be much appreciated and of course I will use any information at my own risk. Thanks.

    Dave, WA7F
    Last edited: Jul 12, 2019
  2. G0GSR

    G0GSR Ham Member QRZ Page

    That's something so critical that you should only trust the advice of a structural engineer. They routinely do load bearing calculations but I'm not one of them :)

    N2EY and WR2E like this.
  3. AH7I

    AH7I Ham Member QRZ Page

    I've used some of the online calculators for beams. Wooden and steel. You could buy two and test one to failure.
  4. W4KJG

    W4KJG Subscriber QRZ Page

    I'm guessing you could go to your building permitting office and ask the question. They may not give you the final answer but they can probably lead you to the best person or method to get the answer.
  5. WR2E

    WR2E Ham Member QRZ Page

    Ha... "Free" engineering advice.

    Yeah... you say that now.

    Ask yourself, would you really trust engineering advice from a self proclaimed keyboard engineer?
    K2CAJ, VK6APZ, NN4RH and 1 other person like this.
  6. KD0CAC

    KD0CAC Ham Member QRZ Page

    You left out what is holding up the beam , then what is holding up the vertical support / footing ?
    Some idea of what you want to hang from the beam ?
    N2EY likes this.
  7. N2EY

    N2EY XML Subscriber QRZ Page

    That's structural engineering, not mechanical engineering.
  8. KD0CAC

    KD0CAC Ham Member QRZ Page

    But generally speaking , if an engineer was involved in the 1st place - the beam should be there to support the building & roof load .
    Unless the builder intended to have the beam for hanging stuff from , the idea being buy enough steel to do the job / with no reason to buy a bigger beam than needed [ to support roof / load ] .
    Most metal pool barns have manufactures name on it - call them - the most likely place that knows there stuff and has " been there done that "
  9. K3RLD

    K3RLD Ham Member QRZ Page

    I should hope that any mechanical engineer could solve this problem. Not likely that any (including me) would publish an answer freely on a public forum. Too many ethical and liability concerns, unfortunately.
    AC0OB and N2EY like this.
  10. WA7F

    WA7F Premium Subscriber QRZ Page

    I’ve seen other forums that provide ME estimates, just can’t seem to find them at the moment. The calculators are providing force in Newton-meters and I’m uncertain how to convert this to dead weight.

    It’s not like I want to hang a car from this either. Basically two beams to hang my 8x16’ white water cataraft (350) lbs, a smaller fishing cat (50 lbs) and two kayaks at 70 lbs each and maybe a lightweight kayak trailer (150 pounds.) So 550 to 700 pounds (say 800 lbs to be conservative) distributed across two I-beams seems feasible. I just want to run my gut instincts by someone that is more knows more about this than me. The amateur approach is too just over engineer everything but I-beams aren’t exactly cheap.

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