Beam Lifting Capacity

Discussion in 'OUR SHOPS AND THE SPACES WE WORK IN' started by TomS, Aug 22, 2013.

  1. TomS

    TomS Active Members Active Member

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    I've got a 350 lb lifting capacity hoist in my shop. Problem is it is hung in a fixed location. I want to hang either an I-beam or H-beam from the ceiling trusses. The beam will be 20' long (two ten foot pieces). I'm thinking of either a 3" or 4" beam and hanging it with beam clamps on 5' centers (clamp picture below). I'm not an engineer and what information I've read on the internet there are several considerations when doing the calcs. Is this size beam adequate for the weight to be lifted? Your input is appreciated.

    Tom S

    4HYR8_AS01.JPG
     
  2. Ulma Doctor

    Ulma Doctor Moderator Staff Member Supporter

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    i don't think you'll have to worry about the I beam at 350 lbs weight it can carry 350 no problem at 5 ft center support.
    But, you may wish to consider that you would be changing the load on the ceiling supports.
    without knowing the construction of your building, it's had to say whether it would be possible/feasible or not.

    S8 X 18.4 A36 I beams would more than sufficient and probably a little overkill.
    but without knowing a lot of variables i wouldn't suggest smaller
     
    Last edited: Aug 22, 2013
  3. Codered741

    Codered741 Active Members Supporter Active Member

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    Hi Tom,

    This is indeed a very complex question, with many factors involved. Off the top of my head, and making a LOT of assumptions, this seems reasonable. The load that you are lifting is not tremendous, and you probably will not have a problem.

    According to the AISC Steel Construction Manual, the smallest I-Beam (Technically known as an "S" Shape) is 3" x 5.7lbf. Calculating for a 5' simply supported span, this gives a Maximum UNIFORM load of 5.58 Kips, or 5,580 lbs. To convert to a point load, multiply by .8, to get 4464 Lbs. Obviously, this beam is FAR stronger than you need to lift 350#. And with 4 mounting points, your span is no longer a simple one, making the maximum capacity greater still. (I will run the numbers for your exact scenario if you ask me to, but its really not necessary.)

    The real area for concern, and not a huge concern in my opinion, is the roof. All modern construction has various allowances for extra loading, Eg. snow, wind, etc. You will be dipping into this over-engineering when hanging the beam from the roof trusses. It really depends on the area of the country that you are in, to determine what the allowable extra loading is. Generally is it at least 20-30 pounds per square foot. So with the weight of the beam, 114lbs, and the load, 350 lbs, and the weight of the hoist, guessing 50lbs, you will be applying about 500lbs to the roof. If you assume 20psf of live load for the roof, a low ball estimate in my opinion, you would need a minimum square footage of 25sf. And since I'm guessing that your shop is wider than 1', your roof should have more than enough extra capacity.

    When hanging your beam, try to attach the hangers at a panel point on the truss. A panel point is a point where multiple truss members meet. This is generally at three or 5 points along the bottom stringer, depending on the span of the trusses. The closer to a panel point that you can mount the beam, the more that the truss will work in your favor, distributing the load more efficiently.

    Again, without seeing the exact structure that you are going to be mounting to, I cannot say for sure. But it seems to me that you will have no problem with this plan. The only problem that you may have, is finding a beam trolley that is small enough for the beam. Of course, you could always make one.

    Good luck!

    -Cody

    DISCLAIMER: I am not a licensed engineer, though I have studied structural engineering, and use these techniques fairly frequently. I cannot claim responsibility for any mishaps that you may have, or if this pulls your roof down! (It won't)


     
  4. Ray C

    Ray C Moderator Staff Member Supporter Moderator

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    Tom,

    You have a good and sound idea. My thought on this concerns the method of attachment to the overhead joists. I presume you will use threaded rod with turnbuckles or, a few layers of strapping or, cable wire to attach the beam clamps to the joists above. For the light loads you're talking about, any/all will do fine but how you attach and bolt them is also important. I would avoid just using lag bolts going from the bottom straight in and try to make a fixture that's attached to the side of the joist and is bolted in at least two spots per attachment.

    Here's a chart that I use a lot. It describes single and double shear forces and has a nice table of the theoretical shear strengths. For all of those values, you need to apply a safety margin that includes bouncing and impact forces etc. A really safe rule of thumb is to use only 25% of the theoretical strength for static loads and only 15% for dynamic loads. I find that to be overly conservative for many things but, when it comes to hoisting things... better safe than sorry (unless you have really good liability insurance). So, an example for a 1/4" bolt, it has a 2179 lb shear strength and 15% of that is 326. As a practical matter, I'd be inclined to use two 5/16" or 3/8" bolts as one day, you might want to use a beefier hoist to lift heavier loads. If you're using lag bolts, all bets are off and you'll need to find a different chart. Also, you'll want to find-out the ratings of those beam clamps.

    http://nucor-fastener.com/Files/PDFs/TechDataSheets/TDS_013_Shear_Strength.pdf


    Ray
     
  5. TomS

    TomS Active Members Active Member

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    Thanks everyone for your input. You've confirmed that the path I'm taking is reasonably safe. For info my shop's mid-span trusses are doubled, e.g. two parallel trusses spaced about 6" - 7" on center. My plan is to straddle the horizontal beams/rafters with 3/8" x 8" x 8" steel plate and drill a hole in the center for a 1/2" hanger rod with a nut and washer. Might even consider using 2 x 8 doug fir boards on top of the beams/rafters instead of steel plates. No lag bolts will be used!

    Here are pictures of my current setup and the truss configuration. I got the order reversed but the last two pictures are of my current setup. Not going to hang the beam here because the door opener is in the way. The first two pictures are for clarification of the truss structure and the new location for the beam and hoist. Not shown in the picture is my lathe that is located directly under the truss. This will give me the ability to lift parts, and lathe chucks, into the lathe without breaking my back. Thanks again for your help and insight. Now I'm heading to the local steel supply house for a beam.

    Tom S

    truss photo 01.jpg truss photo 02.jpg truss photo 03.jpg truss photo 04.jpg
     
  6. reds

    reds Active Members Supporter Active Member

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    The main thing to remember on those trusses is that they were engineered to support weight over the truss, not under. The bottom chord will sag with not much weight attached.
     
  7. Ray C

    Ray C Moderator Staff Member Supporter Moderator

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    Tom,

    I think you're in good shape there. If that were my place, I would probably just buy some chain or cable and wrap it around the beams. Even low grade chain has working loads way higher than what you need... http://www.1st-chainsupply.com/WLLchart.htm#

    Ray



     
  8. markknx

    markknx Active Members Supporter Active Member

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    I agree with all the calcs, andasumtions and I am no enginer, But as a person who rigs for a living I havebeen warned time and again about rigging from the bottom of truss. seea truss is designed to spread a load from top to bottom. The wood is stacked in your truss so down force travels through the wood not the mesh. when you rig off the bottom you put the stress on the mesh conection points. now the question becomes will the conection points hold, and if so will they wear loose over time. Is there a reason that Post can not be used? I would also kick at 5' for side loads. any swing or side pull will work against those conections. And when it comes to rigging never bite into the saftey rating, that is there for a reason. things like a bad bolt, weat spot in the wood, extra heavy snow. I hope you consider these things, not saying this will not work just want you to have all the info you need to keep safe.
    Mark
     
  9. ki4byz

    ki4byz Active Members Active Member

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  10. TomS

    TomS Active Members Active Member

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    I'm not an engineer either nor a rigger but I have been around riggers lifting heavy loads. I worked in a power plant for many years disassembling and reassembling steam turbines and generators. Some of the lifts were as much as 155 tons. My point is I have a lot of respect for those that do this type of work and the consequences of not considering all the safety factors. Seen a few near misses.

    My shop has roll-up doors on each end for drive-thru and the hoist will be located over this area of the shop. Most of the lifting I'll be doing will be less than 100 lbs. In fact the lifting beam and hoist will be heavier than most of the lifting I'll be doing. I do realize that this is a consideration when calculating the total lifted weight. I have to agree that a couple of removable posts for the heavier lifts is a good idea.

    Thanks for your input.
     
  11. John Hasler

    John Hasler Active Members Supporter Active Member

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    You still shouldn't lift from the lower chords of the trusses. Run a threaded rod or chain up to the peak to carry the load. You can still stabilize the beam by clamping it to the lower chords.

    You could add wood to those lower chords to convert them to box beams, but I think that running a rod up the peak would be easier and less expensive.
     
  12. jererp

    jererp Active Members Active Member

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    I have a 2 ton engine hoist, and that is what I use in my shop. Not sure why you don't use something like that. It seems to me to be a much more versatile lifting arrangement. I am leary of lifting from the trusses, since I know they are engineered to spread the weight of the roof over a large area, and I would be afraid of adding point loading of a type the truss is not designed to hold.
     
  13. TomS

    TomS Active Members Active Member

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    John and jererp,

    Thanks for your comments. I haven't done anything with this project yet because I'm not comfortable with lifting from the trusses either. I do have an engine hoist that I use for heavy lifts. It works most of the time but in some instances I have been limited with a lack of reach. Anyway I'm going to live with what I've got until I come up with a better plan.

    Thanks again,

    Tom S.
     
  14. xalky

    xalky Global Moderator Staff Member Supporter

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    As someone else pointed out. The top cord that the roof is sitting on is the section of the truss thats designed to take the load. The bottom cords are in tension and basicallt designed to keep the roof from spreading the walls, and not desingned to take much of a vertical load. Ideally you'd want to hang your beam down from the top with some threaded rod thats attached to a plate that sits on the top cord, preferably at the peak or a point on the top cord where the cross bracing meets. Done in that way you'd be able to load it up quite well. You could attach to the bottom cord for side to side stability, but thats it.
     
    Last edited: Dec 10, 2013
  15. TomS

    TomS Active Members Active Member

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    John Hasler and you have me thinking. Hanging the hoist rail from the top beam may be doable.

    Tom S.
     

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