load testing of bars - any ideas?

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whatfriends

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hi there, im a new member, first post and asking for help. im not a scaffolder but we do use scaff in my line of work (circus). i was wondering if there are any publiished findings of load testing on horizontal bars of different lengths? i have done some googling and mostly come up with body piercing articles, and ive done some searching on this site but couldnt find what im looking for.

ideally i'd like working load limit/breaking load/deformation data for varying lengths of single tube supported at the ends only. and also for clips and clamps if its available.

if this is industry published data that would be great but any kind of help would be appreciated.

cheers in advance.

whatfriends.


oh yes, uk data is best for me...
 
welcome whatfriends iam certain that some of the scaffold designers here will be able to help ( we call bars tubes) :)
 
ha, i just knew i'd be making some kind of mistake. i'll get it right next time...
 
the longer the tube the easier it bends , check in the designer section i think chriseng is about at moment try pm him if not he will point you in the right direction, well he will point you in a direction lol :laugh:
 
The only relevant data from basic CITB scaffolding training would be bay sizes.
2.7m - 0.75kN/m2
2.4m - 1.5kN/m2
2.1m - 2.0kN/m2
1.8m - 3.0kN/m2

The above is based on a standard 50mm scaffold TUBE and it would be safe to asume there would no, as you say, load deformation also based on the above.
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is that for the new light weight tube,or the thicker old school tube,as i think theres a mm or two difference in tube wall thickness.we deal with downward force,hes on about linear.:D
 
cheers folks.

podger, im not quite sure how the m2 bit in the above data fits in. and also what is the data showing? deformation? tubes snapping? (i know its not that).

the longer it is the easier it bends eh? cheers superscaff74 i think i may have figured that bit out. i'll try to locate chriseng and see if he turns up anything.
 
numbnuts said:
is that for the new light weight tube,or the thicker old school tube,as i think theres a mm or two difference in tube wall thickness.we deal with downward force,hes on about linear.:D
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Good point on the light weight tube, imagine it is the same as all the design calcs would be different and drawings would state the wall thickness of the tube. There is some info on sleeve couplers in " A Guide to Practical Scaffolding " which may be relevant which states " the fitting has a resistance to bending that is at least equal to any tube and has a safe working tension of 315kg."




whatfriends said:
cheers folks.

podger, im not quite sure how the m2 bit in the above data fits in. and also what is the data showing? deformation? tubes snapping? (i know its not that).

the longer it is the easier it bends eh? cheers superscaff74 i think i may have figured that bit out. i'll try to locate chriseng and see if he turns up anything.
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The m2 is the SWL of the platform with the afore mentioned bay sizes (standard spacings).
 
ah ok i think i understand now. so for a bay size 1.8m, the platform would be safe to a force of 3kn per sq metre?

how many horizontal tubes in a bay and is the weak link in the above the plank or something else?


just for clarity..


if for example, i ratcheted 3, 3m tubes together and supported them only at the ends and suspended people off them, i know they would hold and be safe. you know they would hold and be safe. but i need to show someone else that there are figures for tubes that demonstrate this.
 
I reckon what ever you were using to attach them at each end would snap long before the tube. Sorry, no calcs to back this up with.
 
Whatfriends, part of your question asked the calcs for clamps (doubles) So I presume that is what you intend to support the horizontal tube. The SWL of a class A double is 6.25kn's this can be doubled by fixing another underneath (check) As stated the bending or sag on the tube depends on the unsupported length. Have you considered using an alloy beam, I have calcs for them.
 
actually the supports would be timbers and wouldnt take clamps. the info on clamps was for pure interest. scaffold is the preffered choice as its in place already and cheap. i just want to beef things up a bit by adding a third tube. the timbers are on an angle and the tubes would be ratcheted down with 5 ton straps at either end and possibly braced in other ingenious ways. sag isnt my concern, in fact sag is good as it absorbs shock loads of performers doing their thing, its more a failure of tube. steel bends before it snaps, i know this, but if a client wants numbers then numbers they should have. truss manufactures provide this info and i just figured scaff manufactures would too but then i suppose im using it contrary to its intended use. maybe i just have to build something and get an inspector in to view or cast an eye over some plans before i do anything.

thanks to everyone for all the posts, im off to bed, i'll check back tomorrow and i'll keep up the google searching.
 
Whatfriends,

The safe working bending moment of a BS EN 39 'as new' scaffold tube (48.3mm diameter, 4mm wall thickness) is 1.12 kNm and the safe working shear force is 29.2 kN. These values are from TG20:08 volume 2, section 39.5. From these values you can calculate the maximum allowable load for each span that you require.
Hope this helps.
 
whatfriends said:
actually the supports would be timbers and wouldnt take clamps. the info on clamps was for pure interest. scaffold is the preffered choice as its in place already and cheap. i just want to beef things up a bit by adding a third tube. the timbers are on an angle and the tubes would be ratcheted down with 5 ton straps at either end and possibly braced in other ingenious ways. sag isnt my concern, in fact sag is good as it absorbs shock loads of performers doing their thing, its more a failure of tube. steel bends before it snaps, i know this, but if a client wants numbers then numbers they should have. truss manufactures provide this info and i just figured scaff manufactures would too but then i suppose im using it contrary to its intended use. maybe i just have to build something and get an inspector in to view or cast an eye over some plans before i do anything.

thanks to everyone for all the posts, im off to bed, i'll check back tomorrow and i'll keep up the google searching.
Click to expand...

Your best bet would be RSJ or your scaffold tubes and get Llyods British to come and test them
 
Hi Whatfriends.
I did sent a pm for you to send my your e-mail so I could help with your original question.

Looking at the later comments your proposal now seem slightly different.

If you are forming a platform for the performers to work from I would suggest that you get a proper design completed so you are covered.

Not sure about a design basis that allows tubes to sag, strapped with ratchet straps and ingenious bracing. ???

This will involve some costs as a designer will be providing his knowledge and you will be covered by their Professional Indemnity Insurance.

I am happy to give advice if required, but this would not be a full design.

Regards

Chris
 
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