breaking strength of horizontal steel or wooden beams?
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Hey, my name is irwanbee, and I first published 'breaking strength of horizontal steel or wooden beams?' on 25th July, 2010, within the steel section.
I need to build a hoist system, and I plan to have two arches with two hoists, starting with two pairs of vertical 6×6″ wooden posts. On the top, I need two beams that span all the way across, which is no more than 15 feet, and I need for it to handle a minimum of 1,000 pounds, with 2,000 being better. I need to know that if I get a particular size of beam that it is unquestionably strong enough. I cannot figure out where to find this information. I have tried all the steel yards and lumber yards around here, they’re all afraid of getting sued or something, or maybe they just really haven’t got a clue.
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4 Responses to “breaking strength of horizontal steel or wooden beams?”
15ft is a pretty wide span.You would probably have to go with at least a 8″/1/4″thick I beam minimum(for the 1/2 ton(12″ would be better)(especially since you are talking of 1 tonTo do it in wood would require laminating 2 by12’s with metal plates
You are talking about some pretty serious structural work for a wooden beam.
As you indicated a steel beam or a glue-lam beam may be more appropriate. If you are in the US then try looking for a Louisiana Pacific LVL (2950Fb-2.0E). I’ve included the link to the technical manual from LP. A number of other manufacturers make similar products (note that the Fb and E numbers represent the bending strength and modulus of elasticity – equal beams will have equal numbers).
The Wood Frame Construction Manual is a great source for some of this information, but it is not easy to find. If you have a college library around where they teach structural engineering or architecture you might be able to find it. . .
A steel beam is easier to design if you can get your hands on the AISC Manual of Steel Construction (in the US). Check a library. A simple beam with a concentrated load in the middle would work like this: Take the load (in thousands of pounds) and multiply it by the length in feet and divide by 4 (2 times 15′/4=7.5kip.ft.). This will give you the maximum moment on the beam (technical term). According to the manual you could use a W6×12 for this example.
Of course you understand that all this load will require a column to support it. The size of a column is related to its height, so you will need to verify this as well. And then a column will need a footing.
I would recommend finding a local architect that can help you. It seems silly until your roof is sitting on your head.
According to the Boise Beam Calculator it looks like a 5-1/8″ x 13 1/2″ glulam beam will suffice to carry a 2000# load both at center or each end. I understand you are trying to accomplish a hoist system? For a garage or similar use? The only thing I would advise to you is lateral bracing. Stacking this beam atop the 6×6 posts and then applying a 2000# load would be like stacking two golfballs one on top of the other and then attempting to stand on them. If you dont have some kind of bracing this system will fall. Remeber when bracing, triangles are a must. Dont forget to brace both parallel and perpendicular to the beam.
dont know