Designing a beam for a 3000# point load

[MushCreek]

This is way outside of building practices, but maybe one of you smart guys know if I'm on track. In short, I have to build a beam and support to handle a 3000 lb. point load, one time, for a few minutes. I need to unload a 3,000 lb. machine from my trailer, inside my barn. My plan was to make a short beam out of (4) 2X12's, supported with posts about 7 feet apart (to span the trailer). I ran it through the Medeek Beam calculator, and it seemed to indicate 'OK'. For posts, I could either use 12' 6X6's, or build them up out of (4) 2X6's. I'd rather use the 2X6's, as I can disassemble them and reuse them elsewhere. I have no use for 6X6's afterwards. The load will be brief; just long enough to move the trailer out from under and lower the chain fall.
No one will be under it, but if it failed, it would likely damage both the floor ($) and the machine ($$$). Other options would be to rent a forklift, or use a steel I-beam instead of wood, but it would be hard for me to get it up to the ceiling. Someday, I'll have a nice rolling A-frame, but I need to unload this machine next week. Thoughts? How well do the 2X6's have to be fastened together to function as a post? Nails? Screws? Bolts?

[Don_P]

I'm coming up with 2@2x12 barely makes it, 3x5.5x12' as a column works. Your solution seems to be plenty.
If the post is braced about midpoint to prevent buckling the fasteners between plies is not that critical.
The beam would be helped by lateral support around the load point to keep it in alignment.
The chainfall needs to be hung so that it doesn't cut into the beam.

[MushCreek]

Thanks, Don! I was planning to attach the 2X12's to an existing 2X10 joist, which in turn is part of the loft diaphragm, so the load point will stay in alignment. I'm not sure how I would brace the middle of the columns. I guess I could fasten a 2X from the mid point up to a joist on a 45 degree angle or so just to make sure. I'll be sure to make sure the columns are plumb. As for cutting into the beam, I was going to drill holes for the chain on either side of my built-up beam, through the loft decking, and I can lay a piece of steel on top to protect the loft deck from the chain. I'll leave the beam in place in case I need to unload something in the future.

[Don_P]

That sounds fine, I was wondering about whether the door header was big enough and had a landing zone under it. The steel on top was in my mind with that comment about cutting in, you got it. The column bracing up to the joists would work, a 2x laying up on edge on the shop floor alongside the post, in line with the trailer with braces up to the post midpoint would be another way... basically anything that will brace the post to keep it from buckling changes it's "effective length". A cap board across the edges of a built up post helps secure the laminations together as well. When we make a temporary prop in the field it is usually a "T" or "H" configuration to resist buckling in either direction. I've wandered out and grabbed a sound locust or oak tree to press into service as well. As a teenager I learned that you should not try to pull an Opel engine with 2-2x4's 

[MushCreek]

The door header is massive, and would probably handle the load without additional support, but it is gravel on the outside, with no way to move the machine on gravel. I have to get it fully inside to be able to move it around the shop. I move machines indoors with an engine hoist, just taking the weight off and shoving it where it needs to go. It's too scary to pick the machine up off the ground with it; I've seen them fail rather dramatically.

[Don_P]

On well raked gravel and then onto the slab you could lay 2 planks, short pipes, planks to set the machine on and do the egyptian log rolling trick. I have dreams of a simple bridge crane set up in the shop one day.

[flyingvan]

http://www.youtube.com/watch?v=bsoYkGb7p28

[UK4X4]

mmm I live 40 mins from Stonehenge, and the stones come from 160 miles away in Wales......there was no neat concrete road for the small stone trick to work....

The way to stand them he's basicly got right, at least thats what people sumise,,,,Wiltshire is also highly regarded as a regular haunt of UFO's

Mean while back to the plot Applied weight does funny things to structures, a simple n can twist under load, you'd need triangulation of the framework to stop this

[flyingvan]

I used his hints to move a few granite stones for our pavilion.  The biggest is 8' x 2.5' x1.5' (approx) I figure it weighs 4,400 pounds.  It took quite awhile.  I have a picture of the kids, as toddlers, sitting on it reading while I slowly moved it..I'll have to find that pic somewhere

[MushCreek]

Well, the deal fell through, which is better than the barn falling through, so to speak. I will still be buying heavy machinery, though, so it wasn't a wasted effort. Maybe I'll get to build that A-frame hoist in the meantime. I bought a 2 ton Yale electric hoist for $70 on ebay, and I'm itching to use it! It went cheap because it didn't work. I took a chance, wired it up according to the manufacturer, and it runs just fine. Thanks for the input and interesting discussion.