I-beam sizing and load ratings

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Old 10-31-04, 03:37 PM
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I-beam sizing and load ratings

Where might I find span and load ratings for various sizes of steel I-Beams?

I want to run 2 i-beams, about 12' long about 12' apart, with movable crossmember that can withstand at least 4000 lbs at it's center without bending, to be used as an automotive/engine/whatever lift.

Also, what might I expect to pay for the steel?
 
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Old 10-31-04, 06:08 PM
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If you manage to find this information I would like to be the first one you tell.

I have looked for simple strength tables for steel but have been unable to find any.

I bought this book to help build a trailer only to find formulas needing calculations that were beyond my understanding. :
<img src="http://www.northerntool.com/images/product/images/176222_med.gif">
Image credit; northerntool .com

By the way, 4000 lb capacity? You lifting the whole vehicle or a CAT engine?

My guess: 4000 lbs on twin beams over 12 feet. I'd say 8 x 8 x 1/4 I beam.
 
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Old 11-01-04, 04:37 AM
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Tell ya what, I'll try to stop by the steel place one day this week and see if they have chart, or can at least tell me what I'd need.

4000 lbs, I have, on occasion, lifted an entire vehicle with a hoist on an old A-Frame made from steel pipe that my grandfather built. Even after having two big pine trees fall on it dead center, it only managed to bend in down about 2'.

They don't make em like they use to, except when I make em. I tend to overbuild and then not worry about if what I am doing is going to break it.

I've been thinking about buying one of those trailer books, so it wasn't very helpful then?
 
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Old 11-01-04, 06:03 AM
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No, this book wasn't what I was looking for.
The author is a "former engineer" who wanted to pass down what he knows about building trailers.
What he passes down are complicated tables that take calculations I don't understand. There is nothing in the book that explains how to use the included tables.

Your comment about "overbuilding" is what I want to avoid when building my 8' x 20' tilting car hauler.
I want strong, but light, which can be achieved by "smart building".
So far, I have a number of ideas on steel selection for trailer building that I got from measurements taken from factory built ones.

I think you have the right idea about asking the steel supplier for advice.
They should have someone that can steer you in the right direction. (And maybe scare you with the price of steel nowadays. )
 
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Old 12-01-04, 07:03 AM
Greg Balfany
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Lightbulb I-Beam Sizing and Load Ratings

I'm looking for a similar guide. I'm helping a friend build a new bridge across a creek at his ranch and we need two sixty foot I-Beams that will cross it and will need to support 25,000 lbs total for the two of them. They need to free span 44' with 8' on each side setting on the ground. The I-Beams will be set 8' apart and will be cross braced.

Is there anyone who can help with identifying what specifications will be needed for this type of load?
 
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Old 12-01-04, 12:32 PM
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Greg Balfany,

Looks like what you are planning is exactly what I built, only yours is for ten times the weight.

I was able to obtain a number of 16' long by 22" deep metal building truss rafters.
After welding three together, I secured one length in an upright position and a heavy friend and I jumped on the centre to note the deflection.
After this diy stress test I now have a 48' long by 4'wide steel foot/snowmobile bridge, with a pt deck and handrail, to span a deep, wide ditch. Now we can now go and watch the ducks in the marsh.

This worked for me but I don't think this would work for you!
You will need some serious engineering from both a safety and cost perspective.

From what info I gathered, by using supports, even at 1/4 of the way from land on each side, you will reduce your span by half.

You might want to take a drive in the country to locate one like what you want to build, to at least have an idea of what you are looking at.
 
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Old 12-15-04, 05:06 AM
oldudbob
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You may be able to find the information you are seeking at this site.

http://ourworld.compuserve.com/homep...s/techdata.htm
 
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Old 01-31-05, 10:22 AM
Albin
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[QUOTE=GregH]No, this book wasn't what I was looking for.
The author is a "former engineer" who wanted to pass down what he knows about building trailers.
What he passes down are complicated tables that take calculations I don't understand. There is nothing in the book that explains how to use the included tables.

QUOTE]

Not true. I have the book here on my desk at work. He does go into great detail on how to use the tables in the back. It helps, however to have an engineering background to get yourself through the equations. I used this book to design and build my 3500 lb trailer.

Specifically, he has a detailed set of instructions starting on page 152 through 154.

Note, however, that he does not include the dimensions and properties for I beams, simply because they are usually not used in building trailers.

Go here to find steel I beam properties. Note that one key, on many, is the section modulus, Z1-1:

http://ourworld.compuserve.com/homep...orhis/T407.htm

Without understanding the equations and how to use them, this info is largely useless to you. That's where an engineer can help, or maybe, a table, dunno of one though.

Good luck.

Al
 
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Old 01-31-05, 12:28 PM
Albin
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[QUOTE=Albin]
Originally Posted by GregH
No, this book wasn't what I was looking for.
The author is a "former engineer" who wanted to pass down what he knows about building trailers.
What he passes down are complicated tables that take calculations I don't understand. There is nothing in the book that explains how to use the included tables.

QUOTE]

Not true. I have the book here on my desk at work. He does go into great detail on how to use the tables in the back. It helps, however to have an engineering background to get yourself through the equations. I used this book to design and build my 3500 lb trailer.

Specifically, he has a detailed set of instructions starting on page 152 through 154.

Note, however, that he does not include the dimensions and properties for I beams, simply because they are usually not used in building trailers.

Go here to find steel I beam properties. Note that one key, on many, is the section modulus, Z1-1:

http://ourworld.compuserve.com/homep...orhis/T407.htm

Without understanding the equations and how to use them, this info is largely useless to you. That's where an engineer can help, or maybe, a table, dunno of one though.

Good luck.

Al
quick back of the envelope, using page 153 of the above book plus the web page data, this is the beam you need (assumes one beam, BTW, which should add conservatism, which is good i.e. Z= 16.6, equation 8, page 153: Z=M/S, M= (4000+1000)x6x12 = 360,000 in-lb, S = 21,600 in-lbs.):

S D wf ws A I1-1 k1-1 Z1-1 I2-2 k2-2 Z2-2
S8 8 4-1/8 23 6.77 64.9 3.10 16.2 4.31 .798 2.07
 
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Old 02-04-05, 04:47 AM
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You can use a W8x18. these are very common beams that are the norm for residential construction. as for the going rate for steel, base cost for W-beams is about 40 cents per pound in bulk. with two 18 lb beams 12 ft long you have about 432 lbs of steel. you dont have bulk so they might charge you more, but the costs are per lb and you can shop around.

Fabricators typically charge to cut each piece, so you can save money even if you have to buy longer beams if that is what they have on the shelf. fabricators will be able to tell you on the phone what lenghts they have in stock as they never throw leftover pieces away.

It doesnt matter whether you get 50 ksi or 36ksi steel. each beam can support about 6500 lbs at mid span. so if your load is centered between the two beams, you should be good for 12000 lb. total.

be careful with your connections. the devil is in the details.
 
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