I want to build an overhead trolley system with a hoist on it. I want to let one end of the top I beam extend past the support so that it will stick out over a pickup bed to unload the truck. Where can I find out what the max load is going to be for the length of stickout for a particular beam?
This question, phrased variously, comes up all the time. Think for a moment, Steve, and you will realize that in this litigious society nobody is about to advise someone on something as risky as overhead beam loading. Then go buy a steel databook. In the last few years I've picked up a couple, one is the Ryerson Steel Data Book (very good) and the other is simply titled "Pocket Companion" by U. S. Steel Corporation, also excellent. Steel handbooks will give you a good guideline. I can only suggest you build conservatively.
BTW your "stickout" beam is loaded in cantilever, if you search try that term.
I have a pretty good background in construction and rigging. I generally figure in a factor of 3 when calculating. So, if I want to lift a maximum of 500#, I would build it to support over 1500#. It allows for wind and cerebral flatulence, things that sooner or later are going to occur.
But, now, I can call my steel supplier and ask what is the cantilever info on X I-beam.
for 6 feet of stick out with a load of 1500 lbs at the end of that stick out , using a single beam ,
s12x31.8 lb per foot beam
you get .0951 deflection at the end of the beam
you get a max bending stress of 2970 psi at the support 6 feet from end
this is a safty facto of 10
using an 8 inch S8x23 lb per foot
you get .32 inch of deflection at 6 feet with 1500 lbs
the max bending stress is 6660 psi at the last support , this would be a safety factor of 6 for a 1500 lb load [ about the max in a half ton pick up
the problem is going to be pushing that load up the 3/8 inch deflection hill
if you can build support into the top of the beam and use an underhung trolly you could safely use a 4- 6 inch beam , but this would take an engineered support for the top of the beam
also remember that as you load the cantilevered section it will create a pulling load on the supports past the closest support to the load
also i can email beam boy zips to any body who needs one the web site seems to be down
i can also design supported beams and engineered gussets if you need them .
no p.e. stamps mind you , that costs more as i have to walk to the end of the office to have the boss stamp it
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