4x6 I beam, what will it hold?

[aczlan]

I have an I beam that came from somewhere (not sure where, has been on the farm for a while)
It is 6" tall and 4" wide with 1/4" thick steel making up both the web and the flange.
It looks like the web is flat. The piece I have is around 20 feet long and 2 people can just pick it up, so I would think it weighs 2-350 pounds.
Looking at making a bridge crane to span the 20' workshop and lift around 1000#

Anyone care to hazard a guess as to if my ibeam is heavy enough?

Thanks

Aaron Z

 

[bcp]

First, you need to know which beam it is.

This page can do that:

Various I-Beam Specifications.

Looks like it might be a W6x12.

Then you need an engineer and a beam deflection formula for a beam supported at both ends and a load applied anywhere on the span. Google "beam deflection calculator"

Or put the ends on blocks, place an overload on it and see what happens, where it can only fall a few inches.

My feeling is that I wouldn't want to be under that 1000 pounds on a 20 ft span with that beam.

Bruce

 

[LD1]

First, you NEED to be SURE what beam you have. And IF this is an actual beam, or just 1/4" plate welded together.

Next, I always reccomend people to download BeamBoy. It is a free download and pretty simple to use.

Unfortunatally, I am at work and dont have BB here so I will give it a go figuring by hand.

IF the beam is a W6x12, the Web should mic 0.230" and the Flanges @ 0.280" with a moment of inertia (I^4) of 22.1

IF that is the one you have......

There are two parts you need to be concerned with. Stress AND deflection.

I always start with deflection: Typical limits are L/360. @ 20', that is 240". And 240/360 is .667" that your beam would be allowed to deflect and still be within the limits.

Using Wl^3/48Ei=d where
W is load
l is length in inches
E is modulus of elasticity (steel is 29,000,000)
i is moment of inertia (22.1 for your beam)

Max load allowed based on deflection would be 1468lbs at a point in the middle of the beam. (distributed loads are a different animal).

To figure the stress (s) use S=Wx/2z
Where:
S is stress
W is load (1468lbs)
x is distance (120" to mid point
z is distance to extreme fiber from mid point center of web to flange (3")

stress is 29ksi:thumbsup:

If it is a A36 beam, which is a common structural steel, which has a minimum yield strength of 36ksi, you are within limits there.

So it "appears" that a 1000lb load on one of these beams at the midpoint (if it is indeed a W6x12) would be well within reason.

But just keep in mind that this advise is worth what you paid for it

For

 

[davedj1]

I'm guessing that the actual span may be a bit less than 20' by the time you get the ends supported. That will help the capacity by being less of a span. Some very good info given already. Is the crane going to move? I'm thinking if it goes just one spot maybe you could anchor the center in a few places. Just thinking out loud here.

 

[aczlan]

I'm guessing that the actual span may be a bit less than 20' by the time you get the ends supported. That will help the capacity by being less of a span.

I have to measure the beam, but the building will be 24Wx32L (met with a contractor yesterday to get a quote)

Some very good info given already. Is the crane going to move? I'm thinking if it goes just one spot maybe you could anchor the center in a few places. Just thinking out loud here.

The beam will move. My dream is to be able to pick something up in one place and set it down in another. I had thought of adding a 3rd track in the middle for a little more support, but time will tell on that.

Aaron Z

 

[LD1]

Keep us updated:thumbsup:

 

[CurlyDave]

My experience has been that every time I have engineered any device around something I already have on hand, I have come to regret it.

Usually ends up being more costly to engineer around the limitations of the beam you have instead of buying the right beam to start with...

 

[aczlan]

My experience has been that every time I have engineered any device around something I already have on hand, I have come to regret it.
Usually ends up being more costly to engineer around the limitations of the beam you have instead of buying the right beam to start with...

That is what I am trying to avoid. If it will work, I will use it. If not, I will find another use for it (perhaps a arch style frame to tow a 2nd tedder).

Aaron Z

 

[aczlan]

16' long, so too short. Grabbed a picture anyways:


Would this ibeam, or a piece of box tubing resist rotation along its long axis better?
Thinking what my wife would call "dangerous thoughts" of making an arch style 2 rake hitch with this for the top and back or top and front pieces...
Something like: http://i712.photobucket.com/albums/ww122/geneseofarmer/Merrimac Farms/11610009.jpg for those who haven't seen one...

Aaron Z

 

[LD1]

Would this ibeam, or a piece of box tubing resist rotation along its long axis better?

Aaron Z

Not sure what you mean here?

If you mean twisting, then yes, box tubing is better.