8 inch I-beam - how much will it hold?

One of the projects involves both re-doing the garage and lifting a ford
4-cyl motor out of a car. There's a fellow selling an I-beam locally, 13
feet long, 8 inches deep, 4 inches wide (no web thickness specified). This
would span the garage nicely - could I rely on it to not bend if I hook up
a hoist to the centre and lift that motor? Supported on the ends only...
Reply to
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thickness
I don't have my blue manual handy, but unless that thing is a brake- formed sheet metal beam, it'll probably handle the car, engine and all. In that size, it's gotta run at least 11-lb per foot.
Your assignment is to get the beam mounted in such a way so that it cannot twist _at_all_ when loaded. Probably the best way to do that is to weld the ends to some substantially larger mounting plates onto which A-frame legs would attach.
Get a trolley for that size beam, and you'd have a nice gantry crane.
LLoyd
Reply to
Lloyd E. Sponenburgh
There are at least 3 standard wide-flange beams that fit that description, running from 10 to 15 pounds per foot. It'd be irresponsible to make a firm recommendation based on incomplete information, but I think it's unlikely you'd have any problems lifting a 4 cylinder engine with a W8x10 (the lightest of the standards) wide flange beam spanning 13 feet as long as you use a little common sense.
Reply to
Ned Simmons
There are engineering tables for that sort of thing. I don't know where the right place to look is, but that's all been reduced to "look it up and run a couple of numbers".
As Lloyd pointed out, mount that sucker so it absolutely positively cannot turn on it's side or fall off of it's supports.
Reply to
Tim Wescott
My father once arrived at a house fire driving the fire truck. The house was located across a stream from the road, with an obviously owner-built bridge between him and the house. So he set his right-seat guy out to take a look to see if the bridge was sturdy enough.
"Wow! It's got 12 inch I-beams under there!"
Well, that's gotta be stout enough for ten fire trucks, right? So off he goes, and in the middle of the stream the bridge sags badly. It's still passable, but it's obviously ruined.
After the fire he goes and looks at the bridge. There are the 12" I- beams -- on their sides, by design.
Reply to
Tim Wescott
The tables are in the AISC Steel Construction Manual, but first you need to know which table or chart to use and how to apply it appropriately. There's lots of jargon and abbreviations in the data that the user needs to interpret and then determine whether any of it is relevant to the case at hand.
For example, the charts and tables assume a factor of safety for structural applications which is much lower than the practice for overhead lifting.
That's a good start.
Reply to
Ned Simmons
...
I have this exact beam in my garage. I have a trolley for it with a one ton hand "rolling chain" hoist. Very handy.
Karl
Reply to
Karl Townsend
There's one born every minute, Tim Paul
Reply to
# 42
I could be wrong but are rule of thumb in my head is a beam should only deflect 1" over 360" of lenght.
Made up beams must be constrained so they don't twist.
Stay inside that, life is good if I didn't blow it.
Wes -- "Additionally as a security officer, I carry a gun to protect government officials but my life isn't worth protecting at home in their eyes." Dick Anthony Heller
Reply to
Wes
eflect 1" over
That rule is for beams supporting sheetrock walls, so they don't crack. More deflection is allowed otherwise.
Reply to
Jim Wilkins
My shop / hangar was made with 4" square pipe posts and 10" purlin thirty feet long - unsupported. But I never hung much weight from them.
Reply to
cavelamb
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Some time, look up the dead/live load capabilities of a 3-1/2" x 12" lam-beam. You'd be amazed.
Consider, they use them to span garage door openings (supporting roof structures) up to 22'.
LLoyd
Reply to
Lloyd E. Sponenburgh
Without knowing the exact flange width, thickness at the edge and web thickness it's going to be a guess, but as someone else mentioned, on a 13' span you are probably real safe.
I can affirm by experience that a 6" standard I-beam, 16' between concrete walls, will support a 1300 pound welding machine in the center.
Reply to
Elliot G
Ned: Baumeister and Marks Standard Handbook for Mechanical Engineer that I have just about ground into unreadable by repeated usage, and I'm not a mechanical engineer, has a table 2 on page 5-32 that shows a simply supported beam which means the ends are only restricted vertically and not welded into a vertical column max deflection is:
f = (W* (5* L^3))/(384* E*I) W= weight applied to center of beam in pounds L= length in inches E= 29* 10^6 if it is steel I = the moment of inertia of the I beam section. Note the way to calculate this is found on page 5-38 of the same book. The drawing is a bit messy but the I factor does depend on the web thickness. It is a no brainer if you have the picture from page 5-38 and all the dimensions from the I- beam
Reply to
Stuart Fields
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Extrapolate from this, if you can (I can't ). I know from having built a press around one, that 8" x 8" beam with 3/8" web and 3/8" flanges will take 27,000lb at the center of a 16" span, without any _visible_ deflection. And that's on the flat (web vertical), rather than with the bending moment on the flanges.
LLoyd
Reply to
Lloyd E. Sponenburgh
The moment of inertia may depend on web thickness, but you'll find it doesn't depend _much_ on web thickness.
Reply to
Tim Wescott
Me neither, I was just trying to offer a near comparison. A beam one size smaller, 20% longer, and a known load.
But my WAG would be that his beam will FAIL at 7100, mine at 3300, and yours at 210,000.
Reply to
Elliot G
And that's a perfect example of the hazards of putting too much faith in handbook tables. Look beyond Table 2 and you'll see a section "Maximum Safe Load on Steel Beams." It deals with load reductions for beams without lateral bracing, which is quite likely what the OP has in mind. That's also one of the factors I alluded to that's in the AISC charts, and it's easy to miss there as well unless you know to look for it.
BTW, the deflection formula you gave is for a uniformly distributed load, not a concentrated load like a hoist at the middle of a span would apply. And in any case, the deflection isn't going to tell you whether the beam is adequate to support a given load.
Was it Rumsfeld who said it's the stuff you don't know you don't know that's the most worrisome?
Reply to
Ned Simmons
All I know is a 12" 20' I beam dropped 8 stories will cut a car in 1/2. My dad in the 1950's was dismantling a build near the Port of Oakland and some lady parked her new Buick right by the no parking construction zone sign. My dad did not stop working as he was the owner of the company and was not going to eat the cost for her stupidity. And the cable broke. Dad said was funny as the police were there when the lady came back yelling screaming and saying she was going to sue them. Cop asked lady to sign this paper. When she asked what is was, he informed her it was a parking ticket. For parking in a no parking zone. Dad did not have to pay for the car.
Reply to
Calif Bill
Rule of thumb is that for wood beams you do the deflection calc first, then the strength calc since wood has a relatively low modulus of elasticity. Steel is the opposite, you figure the strength first since that is likely the limiting factor.
Reply to
RoyJ

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