Double standard design criteria

Hi folks
i have seen / encountered many design that make use of double standards if the axial load at the base of the scaffold are large. Could someone elight me on which code (s) talks about how to go about / considerations for double standards.

Thks
KEP

You.ll get plenty of replies on this Kep. I aint got a scooby,but welcome to the forum :smile1:

Welcome

Hello and welcome.

Firstly there are no specific code(s). From memory I think it's mentioned in TG20 and was in BS5973 (now withdrawn) and all it says is to ensure the standards are evenly loaded!

There are 2 approaches....transfer the load from the single standard to the pair by stopping the double standard and then punching the single standard from between the pair, this ensures equal distribution from the single standard to the pair.

The second method I have seen is to stop one of the pair continuing with the single standard, this however in my opinion does NOT evenly load the double standard. The second standard supporting only 50% of the load from the lifts supported by the double standard with 100% of the load from the lifts supported by the single standard remaining in that standard....which could ofourse include the imposed load.

Other options could be to strengthen the single standard...

There is of course TRIPLE standards, gets even more complicated!

We have only recently completed a design with QUADRUPLE standards with 1,0m lifts! Very tall and very high loads!!

As for catering for the load at the base...yes they will be high. Spreaders and the base need careful consideration.

I've always wondered how the load can be spread evenly with double standards when one of them has all that extra weight if the other doesn't go full height.
I hate to say it but 3 is the way to go surely?

Wouldnt it settle with load,cant travel too far,1 or 2 mm if that?

SWIFTY said:

I've always wondered how the load can be spread evenly with double standards when one of them has all that extra weight if the other doesn't go full height.
I hate to say it but 3 is the way to go surely?

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You are correct Swifty, where one standard stops and the second continues they are NOT evenly loaded for sure.

So by tripling the standards the weight goes more on the middle then evenly on the two beside it,Ive only ever had to put double standards in and then took one up to be honest ,if on say vehicle access would it be preferable to take the inside standard up as then it's the centre standard even though ofset,would taking the outside standard up be classed as bad practise,thanks amazing what threads trigger questions you have always answers for Also I know lads use beams on end that surely would take a sh1tload lol

It used to be common practice to use pairs of steel ladder beams built in column fashion,for this very purpose,but now i think about it,i have'nt seen this in a long while.

That depends on how much higher you are going with the single standard,(punchin)I only ever took the 2 standards up to recommended height and then carry on with your single..

bigfish said:

It used to be common practice to use pairs of steel ladder beams built in column fashion,for this very purpose,but now i think about it,i have'nt seen this in a long while.

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You still see it a lot in London.

I have used ladder beams as standards on quite a few jobs in the past , Anglewest done tower blocks a few years back fully boarded 2 meter high lifts and all the standards went in to design at 1.2m centres the whole way up , seemed to work really well

I have'nt been to london for a few years,it just occured to me whilst reading the thread,that it's not a common site anymore,definately effective and looks good too when done properly

anyone got any pics wit double standards, or is it just 1 standard the ir rite next to the other, as i have never seen a job like that like...

Bet using beams though sometimes the webs get on the way,especially when it's a beam spanning going into a beam standard,sounds like a artform in itself,saw one in lpool city centre with short beams spanning three openings on a splay,lovely job the scaff should have been proud !