Double Standards?

aom

aom

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This was quite a while ago now, but there was a thread where a designer explained why double standards should not be used on every beam job automatically as they can cause uplift on the outside set and put additional pressure on the inside set. I was trying to explain this to a fella yesterday but really couldn't remember the specifics, as usual. Any refresher training, gratefully received.
 
Tried it phil, he was a scaff and wasn't wearing it. One thing baffling the 2day men but you can't baffle your own.
 
I do remember the thread your talking about , but cant remember why , sure it was Alan that had the answer though.
I was always taught back in the good old days that you should put in as many standards each side of the beam as you intend to have punch ups.

I done a strange job years ago that still gets me scratching my heed sometimes
we where doing a tower block about 140 foot high and where the double standards died out we had to punch up between them , when i questioned this i was told it spread the load evenly on both standards , but my way of thinking was its got to be stronger if it goes to the ground. ( i still dont fully grasp it )
 
Haha, new one on me too. I would have agreed with you in years gone by but learned just to keep my mouth closed and never take anything for granted. The flat two bay single lift brace is a prime example.
 
philliosmaximus said:
I do remember the thread your talking about , but cant remember why , sure it was Alan that had the answer though.
I was always taught back in the good old days that you should put in as many standards each side of the beam as you intend to have punch ups.

I done a strange job years ago that still gets me scratching my heed sometimes
we where doing a tower block about 140 foot high and where the double standards died out we had to punch up between them , when i questioned this i was told it spread the load evenly on both standards , but my way of thinking was its got to be stronger if it goes to the ground. ( i still dont fully grasp it )
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Who said that Phil? :amazed::amazed:
 
Think I'll post this one before Friday night fight night kicks off.

Imagine 2 standards @1.0m crs, a span and then another pair. If we load the span it deflects downwards between the middle two standards. If this is a nice stiff beam then the outer two would lift up (we are exagerating the actual displacements but if you can visualise it you should get this). When you brace the pair either end or dump loads of additional lifts / weight in to the outside standards they cannot lift up and so thrust the inner pair more in to the ground and by doing so increase the load.

This is all very theoretical but scaffolds are elastic so depending on loads you are more likely to get a bit of slip on the inner pair, leg shortening under load and corrective bending in the beam which then evens it all out again.

As for double standards - plenty of those on this forum. We'll do a blog to explain this one shortly.
 
IDH said:
Think I'll post this one before Friday night fight night kicks off.

Imagine 2 standards @1.0m crs, a span and then another pair. If we load the span it deflects downwards between the middle two standards. If this is a nice stiff beam then the outer two would lift up (we are exagerating the actual displacements but if you can visualise it you should get this). When you brace the pair either end or dump loads of additional lifts / weight in to the outside standards they cannot lift up and so thrust the inner pair more in to the ground and by doing so increase the load.

This is all very theoretical but scaffolds are elastic so depending on loads you are more likely to get a bit of slip on the inner pair, leg shortening under load and corrective bending in the beam which then evens it all out again.

As for double standards - plenty of those on this forum. We'll do a blog to explain this one shortly.
Click to expand...

I know this is a stupid question, but is it the same effect if the standards are only 250-300mm apart?
 
I thought it would depend on the job, span, length of beam and the like, that been said, I know feck all.:cool:
 
Aom - yes but to less effect to the point it is probably not measurable. Deflected shape is the key to design - exaggerate and think about the shape again. If 1000mm apart the outside would deflect up by say 10mm. If only 300mm then it would only be 3mm. Wanting to thrust something 10mm as opposed to 3mm will generate a different force / load.
 
in my humble opinion as a scaffolder who was brought up in an age before TG ******** and we had to design on site which was if necessary roughly drew by the same manky oily hands that built the job for a design to be made.
beams would always go through 2 sets of uprights which would all be tied to the facade,plan brace accordingly and depending on the span and the height punched off the said beams they could be picked up,and or picked back.
i really dont know why we are having debate as these jobs have been built since the first introduction of the beams unit or ladder,and the old RSJ;)
YES I HAVE HAD A COUPLE
 
Always punch up off top of beam only, this saves on 1 double and it also means you don't have to bend down so far when putting the punch on !!
 
aom said:
This was quite a while ago now, but there was a thread where a designer explained why double standards should not be used on every beam job automatically as they can cause uplift on the outside set and put additional pressure on the inside set. I was trying to explain this to a fella yesterday but really couldn't remember the specifics, as usual. Any refresher training, gratefully received.
Click to expand...

I think we went through this in November 2011.
The beam ends do tend to lift the second standard off the ground, that is not to say that you should not use double standards (in close proximity) which are not the same thing.
 
If the second standards do lift put single on bottom of standard against base plate, so no more floaters!!
 
Havespannerwilltravel said:
I havent seen the flat 2 bay single lift brace aom. I thought it was 2 bays across and 2 up?
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Quite popular round these parts amongst the designers. I have always thought it looks w@nk, but I have since been assured by much brighter bulbs than me that it is infact the strongest way to brace a job, it also makes it easier to climb the job and slide back down at bait time.:cool:

---------- Post added at 09:52 PM ---------- Previous post was at 09:49 PM ----------
IDH said:
Aom - yes but to less effect to the point it is probably not measurable. Deflected shape is the key to design - exaggerate and think about the shape again. If 1000mm apart the outside would deflect up by say 10mm. If only 300mm then it would only be 3mm. Wanting to thrust something 10mm as opposed to 3mm will generate a different force / load.
Click to expand...

Alan Reade said:
I think we went through this in November 2011.
The beam ends do tend to lift the second standard off the ground, that is not to say that you should not use double standards (in close proximity) which are not the same thing.
Click to expand...

So all beam jobs should have double standards?

That is what's wrong when you give this scaff a snippet of info, he takes it, twists it and regurgitates it 2 years later as his own and is wrong.:embarrest:
 
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