huangyhg

garage hoist i-beam size requirement
i want to install a hoist in my garage that is rated for 800 lbs maximum load. the span across the garage is 13 feet. what size i-beam should i be using?
pulling motors out of the race car again? w8x15 should work quite nicely. it has a little extra flange width to pull off the bottom flange. provide some sort of restraints at the ends to prevent rotation of the beam. that will be $125, please.
hi,
i have assumed you are using mild steel for constructing the hoist. after calculating the bending stress, and finding the section modulus, the i-beam should have the following dimensions.
top & bottom flange = 175mm
top & bottom flange thickness = 10mm
middle web = 12mm
total depth of i-beam = 300mm
i'm not aware of any american steel beam with the dimensions listed by hemanttht. i am also not aware of any beam having a web thicker than its flanges. i-beams are not even produced in the us any more. i recommend following zulak's suggestion. it's a commonly available beam with sufficient strength.
also, don't forget to size the support columns at each end of the hoist beam.
actually an "i" beam (american standard beam) works better for hoists than wide flange beams. the flanges are tapered in the inside which works better with the trolley wheels.
i would start with s6x tbd; assuming it is simply supported at the ends only and factoring lateral load due to impact (biaxial bending must be considered. i really do not think it is a good idea to post final sizes due to many unknowns. hoist suppliers do recommend beam sizes to their clients (or at least the bottom flange dimensions that would work with their trolley wheels).
i would consult a local engineer to verify the results and also you need to ensure that the supports (masonry walls, columns etc. are adequate).
good luck
to check deflection:
i = x in^4
conservative simply supported
deflection = (pl^3)/(48ei)
or
fixed ends
def = (pl^3)/(192ei)
where l is you span
wouldn't go over .125 max deflection
analysis agreeds with zulak's recommendation (thats why i gave him his star, sorry no $125). if you wanted the other shapes then s8x18.4, or m10x9 will work using given 800# loading, 13' unbraced length and deflection of l/800.
cheers

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