RSJ/ I Beam/ Universal Beam Selection

If you're not sure, you could always invest in a hard hat

Regards, Tony

What capacity is the gantry?

At 10ft span and hinged (uprights not restrained) rather than fixed ends the metric UB with a 3000lb centre load, deflects .109" with a stress of

9572.4 psi. Which is acceptable. With fixed ends the stress is halved.

The US 6" x 12.5lb beam with the same conditions deflects .161" with a stress of 12093 psi.

So the metric beam has an additional safety factor or greater load capacity...

Tom

You can compare any beam, if you have its "areal momentum" (hope that's your term). Its dimension is m^4 (or mm^4). Bigger values denote stiffer beams. You should find the values for any beam (and maybe need to make a conversion imperial/metric).

HTH, Nick

Not I, but I would like to butt in with a related question.

I want to put a runway beam aong the length of my workshop, mainly for loading chucks & heavy jobs onto the big lathe. It'll probably never be loaded to more than 100Kg, but the transverse steel beams at that point will easily take half a ton & I have a half ton chain block and a beam trolley, so might as well design it to that capacity. The beams are 3m/10' apart. Suggestions please for a suitable beam section?

Thanks

Tim

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Looking at 4000lbs

Not fixed ends

Thanks Tom

Charles

I have a 5" x 3" x 3/8" wall, U shaped beam laid on it back. One end sits on the wall at the back of the lathe between the rafters and the other end sits on top of a Bridgeport fixed head series I mill. Probably 8 foot span. Given that sitting on it's back isn't the best position, the Bridgeport mill/drill wasn't made as a prop and the block and tackle is secured by a wrap of chain and a bolt can the experts work out what load this isn't supposed to carry.

At the moment the biggest rotor it's had to lift is only about 1/2 a ton.

Oh forgot to mention it's the dark gray model Bridgy.

-- Regards,

John Stevenson Nottingham, England.

Visit the new Model Engineering adverts page at:-

Also forgot to mention, any chance of an answer before Monday as there's a rotor in the lathe at the moment and it would be nice to know if I'm safe before I take it out Monday, If not I'll get Gert to lift it out .

-- Regards,

John Stevenson Nottingham, England.

Visit the new Model Engineering adverts page at:-

Sorry, didn't understand how that beam will be supported. On both ends or one more in the middle?

Nick

On or around Sun, 25 Feb 2007 10:32:00 +0000, Tim Leech enlightened us thusly:

So happens I have a table here sent to me by someone in this group, "Steel Joists as Beams".

you're looking at 10' span and maximum point load of half a ton in the centre...

There's a recommendation that span greater than 24x joist depth be avoided. Looking down the 10' column, the lightest beam that qualifies is 4¾ x 1¾ x

6.5lb/ft which has a safe concentrated load of .75 ton. The next one up is 5 x 2½ x 9lb/ft which has safe load of just over a ton.

If you look at

you'll see that although the figures are in metric units, the beams are still imperial sizes :-)

They don't list a 5 x 2½ but there is a 5 x 3 at 13 Kg/m which is just under

9 lb/ft according to me. the abovementioned table says 5 x 3 x 11lb will take 2.9 ton distributed or 1.45 concentrated.

They're all a good deal smaller than the ones I need for my 30' span bridge to take 10T concentrated load...

Thanks for that, I'd envisaged needing something a bit heavier & will be pleased if I don't.

There are differences between 'Joists' and 'Universal Beams', I don't think many sizes of 'joist' are made now. I should think a UB of equivalent size to an RSJ rated for 1.45 ton would do my job quite adequately, though.

What about John's 'Gert saver', then?

Cheers Tim

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On Sun, 25 Feb 2007 18:04:36 +0000, Tim Leech

The other thing to bear in mind is that RSJs have tapered flanges; UBs have parallel flanges. A girder trolley will run better on one than the other.

The link Charles posted is really all you need. The specific link he shows pulls up a table of section sizes and data. The next 'tab' on the page is titled 'bending'; this gives you the allowable moment for any particular section size. For larger spans, torsional buckling is the limiting factor.

At both ends. Actually it'll be 6m long, supported at either end and at 3m.

Cheers

Tim

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Thanks for all the advice.

All that I need to do now is find an 8ft 178x102 beam at a sensible price. Pity the price of steel has risen so much lately. Should have done this 2 or 3 years ago!

Charles

I've just been quoted £40 plus VAT by my not-very-cheap local supplier. Doesn't sound too bad to me! Do you want to colect it next week?

Cheers Tim

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All you need if you understand the language

Thanks

Tim

Dutton Dry-Dock Traditional & Modern canal craft repairs Vintage diesel engine service

Our local scrappie keeps various secondhand rsj's etc in a pile and sells by the foot, look at the seventh picture down:

I'll be in there tomorrow, if you want I'll ask the question. We tend to give our steel scrap to them for nothing, so we can always ask a favour in the future. Nearly a ton of steel scrap already this last week and half a ton of transformers (nothing useful for you folks) we did take some money for the transfomers...:-))

Peter

-- Peter A Forbes Prepair Ltd, Luton, UK snipped-for-privacy@easynet.co.uk

Peter

Thanks. I think that I might have sorted a decent scrappie but he's not sure if he has a suitable beam.He does have some heavy square stuff that I'm after though. Since you're in there and he has something please ask.

Charles

will allow you to "wander the halls" so to speak, without getting all freaked out about liability and such.

That yard looks like a gooder, too.

Cheers Trevor Jones

We've known them for many years, and have always treated them as we would like to be treated ourselves. Much of the scrap railway stuff went in for free, but we always got a proper ticket for it which was all our customers wanted.

It's handy to have a wander round with the camera occasionally, and we do get a few bits and pieces there when we need them, and we usually pay for them, but at a better rate than someone 'off the street'.

Just to have somewhere to take metal scrap is useful for us, especially as so much of the 1950's and 1960's stuff from the railways and electricity boards is at its end of life now. Peter

-- Peter A Forbes Prepair Ltd, Luton, UK snipped-for-privacy@easynet.co.uk