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)
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
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