Raising 24' Truss Uprights

jnobel

Member
Hi all,

Wanted to get some thoughts on what best practise would be for raising 6 x 24' Truss Uprights safely and easily. They will be sitting on the upstage edge below an LX/drape line.

Trim is 24' for the uprights. Could be decreased by 2' or 4'. Drape/LX truss will be at around 28'/30'. All truss is 12" box truss.
Hung on each upright is 4 x Magic Panels at around 45 lbs. per fixture. They will be clamped to a pipe hung on the downstage face of the truss.

I've attached a front facing plot to this post.

My plan is just to raise the uprights with the drape line truss and then lower them onto their base plates. Are there any ideas other than this?

Thanks.
 

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As someone ignorant of such rigging, when you all say 'point' you are implying that he should secure the top of the truss towers to something in the overhead? As a caveat, this isn't something I'm attempting to do, but I'm just curious.
 
A "point" is a rigging point. A truss motor or other mechanical lifting device hangs from a "point."
 
As someone ignorant of such rigging, when you all say 'point' you are implying that he should secure the top of the truss towers to something in the overhead? As a caveat, this isn't something I'm attempting to do, but I'm just curious.

To be more specific, a "point" is not just "something in the overhead". It's a structural component that has been designed (or approved by a structural engineer) to support a point load (i.e., all the force exerted by the load is concentrated at a very small area). A typical application (the one discussed here) involves securing the chain of a chain motor (a device that attaches to a load and basically climbs a hanging chain to raise the load) to a rigging point to lift a truss or other object overhead.

I'm glad you're not planning to attempt any rigging, but I feel compelled to add some common safety warnings. First, it's never safe to assume that it's OK to hang a load from a structure that hasn't been specifically designed or approved (again, by a structural engineer) to support such a load. Many building components are engineered to support only the weight of the building itself (plus a safety margin, of course) and will not safely support additional loads (i.e., roof trusses are engineered to support the roof, and a few hundred pounds of gear hanging from them may exceed their capacity). Very, very bad things happen when structural components fail.

Second, even when appropriate rigging points are available, safely lifting and suspending a load from a rigging point requires extensive knowledge of physics, materials, and equipment. Qualified riggers have been trained to assess all these factors and devise an appropriate scheme for lifting and suspending a particular load. Overlooking any one factor could lead to a catastrophic failure of the system. Again, very, very bad things happen when overhead rigging fails. Rigging is not something to be attempted by amateurs!
 
The real challenge in rigging comes from what is taught in architectural engineering. Specifically, you can fail the course just as fast by over-designing a building as you can by under-designing. There is the building weight, expected contents and safety factor. Since most buildings (roof structure) have a snow load designed in, riggers must be able to judge how much of a window of additional weight can be added, and what focus points bear the load and are capable of handling additional load. The second challenge is to be able to hang and lift the load and here is where some real problems can happen.
I will use this fictitious layout- Truss on two good lift points. truss load is 1500 pounds. Only if the truss is level and evenly loaded will the lift points have a static load of 750 pounds (plus the hoists.) When you lift the truss, you also have a motion load to add as well as leveling load.
Lets take it one step further- We'll lift with 3 hoists. If any of the three hoists gets ahead of the other two your loading may go wild. To some extent a truss will flex, but if your center hoist gets ahead of the other two, you find yourself with 1500 pounds, plus the weight of the hoists, plus any motion load all on the center point!
Rigging, like power and pyro, does not have the option of failure. Your best bet it to hire a well insured rigging firm, even if you are 99% sure of what you are doing.
 
Plus, the center point on a truss with 3 points will take around 50% of the weight. For example if you have an evenly loaded truss that weighs 3000 lbs, the outside points will take around 750 pounds each, and the center point will take around 1500... Once again, one of the reasons qualified riggers are very important.
 
Rigging is not something to be attempted by amateurs!

Your best bet it to hire a well insured rigging firm, even if you are 99% sure of what you are doing.

...qualified riggers are very important.

A good common theme. I'm a TD in a theatre with a counterweight system, so rigging for us does not extend to what has already been predetermined as safe in the playbook designed by the fine people at Secoa. And when I get to the point where we move beyond that, I know enough to pick up the phone and find someone who's been down that road. I am however fascinated by you arena guys. The math and physics involved in determining these rigs is amazing. We do occasionally have groups that bring in their own truss and set up on our stage, so I do like to keep aware of what's considered safe practice, at least so I know when to speak up.
 
Thanks for the info everybody! Just wanted to give you guys a quick update on how they ended up...

We ended up putting together 24' sticks and hanging them off the bottom, downstage chord of the drape truss. They were suspended by gak-flex which was more than enough to take the weight. To stop them from flopping around we simply lowered the drape truss to a bit lower than 24' off the deck, pushed the bottoms of the vertical truss over the edge of the stage and let them rest, still floating, against the upstage edge. Doing that also made the truss sticks do a cool looking lean forward, as the downstage chord of the drape truss was not exactly in line with the stage edge.

Snapped a quick pic for you guys at the end of load in and will be sure to grab a couple during show as well. The Magic Panels look killer. Check it out: http://imgur.com/jNPl2FO
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is supporting from the end plates within the manufactures recommendation? I've never seen it done before, Not saying its wrong just asking for my own knowledge.
 
Eagerly awaiting more pics, which profile did you use for the Magic Panels? What console did you use?
 
Used the 160 ch. profile for the Magic Panels.

Consoles were an MA2 Light for the entertainment LD and an Avo Sapphire for the rest of the show. Did have a Catalyst set up to run content but given the type of show (corporate looks the whole day + a 60 minute performance by Brian Wilson) it was not necessary.

I have to say I was very impressed with the Avo's ability to simply and easily handle these fixtures. The pixel mapping feature is very intelligent and makes it very easy to manoeuvre through and create complicated effects. The ability to overlay a basic "shape" (spiral, ripple, waves etc.) across a group of fixtures and multiple parameters to create huge looks was great.

Specifically with the magic panels, the ability to do that not only with R, G, B and Dim, but also as a pan and a tilt effect was really interesting and unique. To my eye, the Magic Panels ability to infinitely rotate pan and tilt looks infinitely better than any other fixture with finite pan and tilt abilities. The beam effects and shapes that can be created are something that concert goers are not used to and so it has a certain awe and grandiose that is conveys.

Also, they are extremely bright. And the quality of light compared to say your average Mac 301 or Aura was much better. I have seen many concert tours that all look very similar because the fixtures all have the same LED quality output. The Magic Panels actually put out a more natural beam, even though it is square shaped and has no focus capabilities.

I was only able to snap a couple pictures from my phone that do not do justice at all. You can roughly see the distance of my spot position. At that distance the Magic Panels were extremely bright and I found myself having to squint suddenly several times.

Thanks again for all the insight guys!
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