Sorry to hijack the thread, next year I'm re-roofing my garage and part of that involves replacing the existing timber purlins with steel beams as we are taking out an internal dividing wall that they currently rest on so it will need to span two bays (probably about 20 feet. This is a brick building with double skinned walls so 9" thick and a pitched slate roof so the beams will be sat on brick and I can build additional pillars under the ends if needs be to add extra support.. Its crossed my mind to over-spec the beams so I can run a beam trolley on them and use them to pull engines. Any idea what sort of size of I beam I'd be looking at, biggest engine will probably be my small block chevy so a fiar bit of weight plus the roof.
Most brick buildings (at least on this side of the pond) have the brick as just the wall covering and
not as a structural item.
So you'd have to design and put in support posts for the beam. Plus footings/foundation for those support posts.
Even if the existing brick walls -are- 'structural', it would be rather unlikely they are strong enough to handle the existing roof+wall loads and an additional beam+hoist+heavy-weight load, so you'd still probably have to put in support posts for the beam. Plus the footings/foundation for the posts.
Putting in support posts and a beam usually means you need a 'pro' to design and stamp/certify the structure. Pro being an engineer or maybe an architect.
Just as a quick ball-park size check, to span a 20 ft length and stick a 1000 lb load in the middle of it (simulate hoisting a big-block+the trolley+some yanking), change the load to 3000 lb to put in the required safety factor shows a rough minimum required beam size of a W12x26 A36 steel beam. The limiting factor (as often with mid-span loaded beams) is the bending of the beam. In this case, a 3000 lb load in the middle of a 20 ft long simply-supported W12x26 beam gives a bending stress of ~6 ksi against a max allowed bending stress of 10 ksi = safe.
A W12x22 A367 steel beam (next size down) does not meet the bending stress limit = NG.
A W8x21 A36 steel beam just barely meets the bending stress limits at 11.5 ksi calculated versus 12.7 ksi max allowed.
That's a rather big chunk of steel. And a rather big chunk of money to get that big chunk of steel.
Actual 'crane' design codes typically call for higher required safety factors (5x or 10x, depending on if used to hoist personnel or not), as well as design and inspection certifications.
At a 5x safety factor, your 1000 lb load is now 5ooo lbs for design calculations and that big W12x26 A36 steel beam just barely squeaks by as 'adequate' in bending at 9.88 ksi calculated versus 10.10 ksi max allowed.
disclaimer: this advice is not legally binding, objects in mirror are closer than they appear, flammable substances may be inflammable, actual mileage may vary, no puppies were harmed in the making of this film, this calculation worth what you payed for it (zero), etc, etc, etc
Building Codes are usually sized/made for the building itself. A trolley-hoist beam is not in the usual BuildingCodes, so you 'd have to get an engineer (or architect) to do the calcs and stamp/sign-off on it.
Trying to put in a roof beam that is holding up itself + the roof loads + a trolley/hoist load means the required beam is much bigger than the aforementioned W12x26 A36 beam.
You really do need a licensed structural design engineer to do all the 'certified' calcs if you are going to put in a beam hoist.
