Sky Hooks....

[slim_mcslim]

Any ideas how one would go about getting permanent hanging points from a building's RSJ's.

 

This is a "new" build and the RSJ's haven't been specced yet, so that won't be a problem, the load factor can still be calculated in.

 

My question is really how would you specify the points ?

 

From what I know about the project is that the architects have never done a project so big and certainly not a venue before, and the steel fabricators have probably never had reason to include fixed hanging points in any of their previous jobs.

 

The sort of points I have in mind are the ones that seem to be a fixed eye welded on the underside of the RSJ, although I am sure there is a more technical way of asking for it, other than an eye welded to the bottom of the RSJ!!!

 

I am looking for 750kg max points, probably only 500kg points, which will as standard be loaded with no more than 300kg.

 

 

Our involvement in the project is to supply and dead hang truss, but apparently we need to design the points as well!!!

 

 

 

P.

[jimbo7744]

If your asking for 750Kg but think you only need 500Kg and reckon it will be no more that 300Kg's then ask for double the 750Kg.

Give yourself some ability to move on your load requirement, but also obviously bare in mind the extra cost.

Either that or ask for certification to use girder clamps or strops at a higher rating above the 750Kg's.

 

If you don't ask, you don't get!

 

 

Jimbo

 

And the total distributed load over the span as well!

[Andrew C]

I'd go for getting the beams rated for point loads, and buy slings, or perhaps preferably, clamps. More flexibility down the line. Oh, and +1 for going for at least twice what you think you need now!

[GRisdale]

I'm sure there are others, but I've certainly seen such things from Rigging Partnership.

 

From what I know about the project is that the architects have never done a project so big and certainly not a venue before, and the steel fabricators have probably never had reason to include fixed hanging points in any of their previous jobs.

The bit about the architect is worrying - this normally ends in disaster frustration. Speaking from experience, it is worth making clear to them / the other contractors, that those I beams are exclusively for stage rigging. In other builds (like warehouses, factories, supermarkets etc.) it seems that any I-beam going is fair game for cabling, ventilation, water and gas pipes, aspirated fire detection pipes etc. People don't like being told that they have to move all such things after the oblivious architect has signed it all off.

 

As for the steel fabricators - you'd be surprised. Industry asks for structural points all the time - normally requiring MUCH greater loads than are seen in entertainment.

 

Gareth.

[Seano]

I am sure there is a more technical way of asking for it, other than an eye welded to the bottom of the RSJ!!!

 

Actually, not much more. :P What you're referring to is a 'pad eye'. As with shackles, you'll find the limiting factor is size rather than weight capacity - you should make sure the eyes are big enough to accept a 5/8" nominal (ie: 3.25t) shackle. If your eye is big enough, it'll be a good deal stronger than you need it.

 

Check out the incredibly useful Crosby catalogue for precise dimensions (of a 5/8" nominal screw-pin anchor shackle). While you're there you could also take a look at their pad-eyes (under 'rigging accessories), and it might also be worth taking a look at the "Weld-on Pivot Link" for a neat alternative to a simple eye.

 

I'd be more inclined to go with a beam clamp myself though. Is there a reason you want to avoid the use of a clamp?

 

The bit about the architect is worrying - this normally ends in disaster frustration. Speaking from experience, it is worth making clear to them / the other contractors, that those I beams are exclusively for stage rigging. In other builds (like warehouses, factories, supermarkets etc.) it seems that any I-beam going is fair game for cabling, ventilation, water and gas pipes, aspirated fire detection pipes etc. People don't like being told that they have to move all such things after the oblivious architect has signed it all off.

 

This is excellent advice, you should definitely heed this!

[slim_mcslim]

I will check out the crosby catalogue.

 

Indeed a Pad Eye is exactly what I had in mind, and yes, I did want a big enough hole for 3.25t shackle.

 

The main reason for fixed points over clamps, is that these points will end up inside a false ceiling, and I intend on putting in about twice as many points as I want for the house trusses as this will give future flexibility. To me a clamp doesn't look like a permanent point where as a Pad Eye is.

 

We will see what happens with the architect and stuff, although from the drawings I have seen there are no services running where I would want points putting.

 

 

P.

 

 

Crosby website is quite a good read, interesting information.

[Glyn Edwards]

We will see what happens with the architect and stuff, although from the drawings I have seen there are no services running where I would want points putting.

 

Yet!

 

I had a similar set of drawings, as did all the principal contractors. Sadly the information that the steel work had to be kept clean didn't make it to, or wasn't listened too (more likely) the boys that actually fitted out the space.

 

We finally got it sorted, but several people weren't happy about the amount of re wiring they had to do.

 

Get it in writing, make sure the site team are aware of the fact and then check every day, at least.

 

Good luck with it.

 

Glyn

[robloxley]

The main reason for fixed points over clamps, is that these points will end up inside a false ceiling, and I intend on putting in about twice as many points as I want for the house trusses as this will give future flexibility.

But also consider the cost of welding and testing (probably in-situ) of such 'fixed' points over getting some calculations from the architect/steel fabricator and buying some girder clamps. Also a girder clamp gives much more flexibility in positioning than a 'fixed' point, however many of the latter you get put in.

[AndyJones]

+1 for getting some beam clamps, Once you have had the beam rated, you simply pop up a ceiling tile and put your point in.

Easy life!

 

AndyJones

[Pete McCrea]

Another for the beam clamps. It would give you the flexibility to move the points if required, and as others have said potentially takes the problems out of getting a pad eye fixed in the right position.

 

For the beam clamps it would be a case of getting the architect to specify the correct Point load over the beam. I would suggest getting it over specified too, as the ability to add a couple of hundred kg now during design could be worth the effort, and probably doesn't add too much to the steel sizing. It might be worth getting the beams specified to take 5t made up as 1t point loads.

 

A large venue near me has had steel beams put into the roof at the design stage- the 'Green' beams were rated to X Tons, the 'Blue' Beams to Y Tons, so rigging is a case of putting your clamp(s) on the beam and ensuring you don't overload the rating of the points. They also have Pad eyes on the nodes of the balcony roof steel work, but these are a pain to use as the pads are not the right size for 3.25t shackles...

[Seano]

But also consider the cost of welding and testing (probably in-situ) of such 'fixed' points ...

 

Pad eyes are cheap, welding and testing aren't difficult (at least, if the welding is done *before* the beam is in-situ). I'd be surprised if the pad eyes aren't significantly cheaper than beam clamps even so. As long as they go on in the right place first time, anyway.