Lifting gantry

[Shox Dr]

This has been disussed on here before, (at least twice). I'm sure one of those threads had drawings in them

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[Wendelspanswick]

I have the beam calculator software on my tablet, I can look it up for you later today.

 

[tinman123]

I have the beam calculator software on my tablet, I can look it up for you later today.

ooh... and sorry for going a bit off topic but...
could i be so bold and ask you if you could check something for me if its not a three day camel ride to do it that is.

i have here a gantry crane i bought a few yrs ago, its for a bigger workshop id like to build for myself in the near future.
its a 3T morris gantry crane, it will only be spaning half of the shed so the lth of the beam would be 6m.
i was taking a rough guess at it and i was going for 406x140x53 but maybe you could enlighten me some more.
there is also the bit where it would need to be good for the best end of 5-6T even if its only lifting 3 or am i wrong in that.

there is also the question of what size the colums/beams would need to be but i dont know if you can do that calc and i dont want to be annoying you tbh but id appreciate any help all the same.

 

[Wendelspanswick]

ooh... and sorry for going a bit off topic but...
could i be so bold and ask you if you could check something for me if its not a three day camel ride to do it that is.

i have here a gantry crane i bought a few yrs ago, its for a bigger workshop id like to build for myself in the near future.
its a 3T morris gantry crane, it will only be spaning half of the shed so the lth of the beam would be 6m.
i was taking a rough guess at it and i was going for 406x140x53 but maybe you could enlighten me some more.
there is also the bit where it would need to be good for the best end of 5-6T even if its only lifting 3 or am i wrong in that.

there is also the question of what size the colums/beams would need to be but i dont know if you can do that calc and i dont want to be annoying you tbh but id appreciate any help all the same.

That completely slipped my mind, I will sort it out for you in the morning but if you have an android tablet the software is free, its called BeamDesign, you also need Profiles which has all the UB and UC information in, again that's free.
If you need complex calculations you have to upgrade to the paid version but for simple calcs its free.

 

[Wendelspanswick]

Here's the links:
https://play.google.com/store/apps/details?id=nl.letsconstruct.beamdesign&hl=en
Profiles:
https://play.google.com/store/apps/details?id=nl.letsconstruct.libraries&hl=en

 

[tinman123]

i downloaded it alright, and the beam one for the sizes but its like being thrown into the deep end of a pool when you dont know how to swim to me tbh.

 

[Wendelspanswick]

i downloaded it alright, and the beam one for the sizes but its like being thrown into the deep end of a pool when you dont know how to swim to me tbh.

No problem, it took me awhile to get to grips with it!
So your beam has a 6m span, the first beam to pass with a 5 ton load on the centre of the beam is a 254 x 146 x 31KG:

It looks like you get a 24mm deflection on the beam.

Here's the previous beam to the one above that fails:

If you have a specific beam in mind let me know and I will stick the figures in.

 

[Wendelspanswick]

Hello clever people I'm looking at making a mobile lifting gantry that will support 1000-1500kg max and it needs to be 9ft wide to fit between the beams in the workshop. What size of RSJ do I need obviously overkill as in terms of SWL is a consideration but what does say 63 or 77 meters per ton mean in English?

9' is about 2.75m, 1500kg on the centre of the beam, a 127 x 76 x 13kg will pass with 0.65mm of deflection.

 

[dan.taylor.1]

Does it tell you if it's passed or failed, or is it just the deflection you're going off?

 

[Wendelspanswick]

Does it tell you if it's passed or failed, or is it just the deflection you're going off?

I'll show you a fail.
Here's the same beam as above with a 40000kg load (its actually KN):

 

[Wendelspanswick]

Just to add I am not a structural engineer so these calculations are taken as face value from the free app, as always if you are unsure seek professional advice!

 

[Welderpaul]

So your beam has a 6m span, the first beam to pass with a 5 ton load on the centre of the beam is a 254 x 146 x 31KG:
It looks like you get a 24mm deflection on the beam.

Which fails....

There's certain deflection limits to worry about when designing beams i.e when the beam goes from elastic to plastic deformation. It's covered under BS5950 I think

Even 5T UDL is a lot for a 254*146. I'd be expecting 305*165 ish.

 

[Wendelspanswick]

Which fails....

There's certain deflection limits to worry about when designing beams i.e when the beam goes from elastic to plastic deformation. It's covered under BS5950 I think

As I understood it thats what the software calculates, a 24mm deflection over 6m on that beam is within the deflection limit, the lighter beam deflects more and fails.
The calculations don't allow for NWL only the theoretical failure level.
To be safe you would need to decide on your safety factor and impose your maximum load multiplied by your safety factor and calculate a beam with that total load.

 

[Paul.]

Maximum deflection is normally span divided by 360 so for a point load on a simply supported beam 2740 long, maximum deflection should be no more than 7.6mm

 

[Welderpaul]

As I understood it thats what the software calculates, a 24mm deflection over 6m on that beam is within the deflection limit, the lighter beam deflects more and fails.
The calculations don't allow for NWL only the theoretical failure level.
To be safe you would need to decide on your safety factor and impose your maximum load multiplied by your safety factor and calculate a beam with that total load.

Dunno. As I understand it, it's the deflection limits that are often more important than what the beam would take to bust it. The software can't take that into consideration (properly) imo.

Maybe 24mm of deflection on a lifting beam would be alright, but if I used the same beam, same span, and put the same load, but in masonry, on top of it, supporting my house, the same 24mm deflection would mean the brickwork cracked and fell apart and maybe started dropping out. Deflection limits are different for different jobs.

 

[tinman123]

No problem, it took me awhile to get to grips with it!
So your beam has a 6m span, the first beam to pass with a 5 ton load on the centre of the beam is a 254 x 146 x 31KG:

It looks like you get a 24mm deflection on the beam.
View attachment 80554
If you have a specific beam in mind let me know and I will stick the figures in.

what i had picked out was a 406x140x53 but its somewhat of a special order so it would be easier to get 406x140x46 kg/m
and that scientific engineering result was from a few coats of looking on just.

re the app.
the numbers on either side of the span that are above the two triangles in pink ( load points i take it), can they be changed or what do they represent as i had 10.000 on mine when i was messing iirc.

with help from your description i had checked the 406x140x46 with a 60.86 [kn] which i take to be about 6 odd tonne? and the deflection is cuming out at 8.31 in the bow dimension and in the green triangle under that it says -91.29 whatever that means.
im not sure if thats a dash or a dot before the 91 either.

 

[PhilTalon]

View attachment 80555
9' is about 2.75m, 1500kg on the centre of the beam, a 127 x 76 x 13kg will pass with 0.65mm of deflection.

Ah many thanks for that, turns out there's a salvage yard a mile up the road selling just what I need for £25 and he'll deliver it for free!

 

[Farside]

but then I got a girlfriend with a big workshop and overhead electric hoists

I've heard of such fabulous creatures, but surely they are few and far between. Did yours come with a brewery, too?

 

[CornishPete]

it's surprising just how much a small section beam will take.

 

[Kent]

I'll explain in a little more detail... I'm moving in to doing recovery and tipper bodies but there is no room for a fork lift from either side due to the ceiling height in the workshop, the work area is 20x10ft in front the main doors where the ceiling has been removed. A gantry on wheels would allow me to pick up the bodies from the trestles and bring the chassis cabs under them, the most it would lift usually would be 200-300kg body or maybe 500kg if I lifted the back end of chassis cab to change an axle?

As such is a regular commercial venture I should get it professionally tested. Just been done on a job I am on for the one lift the frame in question
will do.