Birdcage Design??

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KGB

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Hi all,

I am new to this forum so be gentle with me!!!

I am trying to find out if a design is required for (all?) birdcage scaffolds. Based on reading the section on special scaffolds in TG20 I think that it is (but what do I know!), however, I have a scaffolder who says that he has checked with his designer and the birdcage already erected is a "standard solution in TG20:08, therefore no [design] input required" and "As with standard soloutions contained in TG20-08 orignial calculations are archived in NASC".

The scaffold we have that has already been erected is a internal birdcage with 1 boarded lift 14m high some of which is founded on sloping concrete floor with part founded on stairs that are on a balcony). As part of the structure around the perimiter of the birdcage each lift is fully boarded.

Any thoughts welcome>>>

KGB
 
KGB said:
Hi all,

I am new to this forum so be gentle with me!!!

I am trying to find out if a design is required for (all?) birdcage scaffolds. Based on reading the section on special scaffolds in TG20 I think that it is (but what do I know!), however, I have a scaffolder who says that he has checked with his designer and the birdcage already erected is a "standard solution in TG20:08, therefore no [design] input required" and "As with standard soloutions contained in TG20-08 orignial calculations are archived in NASC".

The scaffold we have that has already been erected is a internal birdcage with 1 boarded lift 14m high some of which is founded on sloping concrete floor with part founded on stairs that are on a balcony). As part of the structure around the perimiter of the birdcage each lift is fully boarded.

Any thoughts welcome>>>

KGB
Click to expand...

It's a tricky one without knowing a little more information but it appears that he is correct as long as the basic following points are covered:-

- The birdcage only has 1No working lift with a SWL of 0.75kN/m2 max
- The working lifts on the outside bays have a SWL of 1.50kN/m2 max
- The birdcage will be built with standards not exceeding 2100mm with lift heights not exceeding 2000mm (apart from the base lift which can be 2500mm)
- Bracing in both directions must be at least every 5th bay.

If that is the case then it should be ok.


-
 
In the current TG20:08 section 19, page 68 states that "structural calculations should be made for all special scaffolds." This means only independents can be constructed with no further calculations being produced. I believe this will be changed in TG20:13, allowing scaffolders to build a wider range of scaffolds without calculations or specific designs.
 
You've just stiched a scaffolder right up there, mate...
 
biffo0911 said:
In the current TG20:08 section 19, page 68 states that "structural calculations should be made for all special scaffolds." This means only independents can be constructed with no further calculations being produced. I believe this will be changed in TG20:13, allowing scaffolders to build a wider range of scaffolds without calculations or specific designs.
Click to expand...

Spot on biffo standard scaffolds only have two lines of standards.
 
I thought only special scaffolds erected prior to tg20 and still standing when that technical guide became compulsory escaped specific design input??just to cover yourself why not ask a design engineer to put some calcs to what's there:cool:
 
Guidance above is about right but what I always advise in these instances is - What does your cusotmer or Main Contractor ask for?

It may well be TG20 compliant but there aren't many mainstream contractors who'll buy that and would expect to see a design anyway for record purposes if nothing else.

They tend to look a bit daft if there is an incident and they say "we don't have a design we were told we didn't need one".

Designs aren't just to pee off scaffolders (which I'm not adverse to) but they are also used to co-ordinate other packages which you might not even be aware of - hence the design / dwg can come in handy.
 
what is the basics for calculating the freestanding height of a birdacge ? on a indpendent / tower we use the smallest base dimension as a guide - is this the same for birdacges?

Cheers

OB
 
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