Basic Trussing Questions

[StageTech620]

I'm looking to hang some lightweight moving heads (under 50lbs each) on a truss. Above the stage is 2 beams, about 12 feet apart, perpendicular to the stage. (running vertically from downstage to upstage). After speaking with a local rental production company, we decided that using a 15' 12"x12" truss set on top of the beams (spanning in between them), and of course securing the truss around the beam, would be a safe and efficient way to hang the fixtures.

Is this a safe practice? Putting a truss on top of a beam, instead of hanging it?

I still can't get a clear answer on this from the production company, just for my own knowledge: Does it matter which chord the moving heads are clamped to? (There will be 2 on the bottom, 2 on the top since it's a square truss. Shouldn't the lights be centered on the truss?

 

[egilson1]

Can you do a quick sketch?

 

[StageTech620]

This was extremely quick so don't judge it too hard haha. Hopefully this will give you a better idea.

 

[Amiers]

If the truss is secured properly and everything stays in the specs of the WL of what the beam can hold everything should be fine.

Personally I like the it's on top and not dead hung. Because movers move and a dead hung truss with 4 movers at that span is bound to get some swing without a 3rd point.

But that's just me.

 

[porkchop]

In an effort to be somewhat helpful without giving too much rigging advice over the internet, truss is commonly placed on top of a perpendicular run of truss. Generally this keeps the load bearing connection points on the truss in compression which is how most truss is designed to be used.

 

[bobgaggle]

Are you more likely to fall if you stand on a beam or hang from it by your fingers? As said above, stay within manufacturer limits when it comes to the loads you put on it.

 

[egilson1]

I think the biggest challenge you will have is figuring out the proper manner to attach the truss to the top of the beams, and that isn't to complicated. AS previously mentioned, in this situation compression is going to be your friend.

Ethan