ProSoundWeb Community

Sound Reinforcement - Forums for Live Sound Professionals - Your Displayed Name Must Be Your Real Full Name To Post In The Live Sound Forums => Lighting Forum => Topic started by: John Louis Griffin on August 25, 2011, 05:29:20 pm

Title: SOP for overhead trussing?
Post by: John Louis Griffin on August 25, 2011, 05:29:20 pm
Hi all. I Am venturing into the market for school dances. I would like to know if there is a standard operating procedure for hanging trussing from a ceiling in a school gym. NOTE: I am NOT going to attempting to rig it myself. I AM NOT a professional rigger. that said i will be hiring a professional rigger.what i would like to know is how do i approach this task. How do i find/locate a quality rigger? google searches keep turning up results for crane operation riggers? what equipment should i buy or rent gig by gig in order to do this? Etc. Etc. Any Information would be incredibly useful.

Thanks In Advance,
JL Griffin
CEO of CG Entertainment
Title: Re: SOP for overhead trussing?
Post by: Doug Fowler on August 25, 2011, 05:46:22 pm
Hi all. I Am venturing into the market for school dances. I would like to know if there is a standard operating procedure for hanging trussing from a ceiling in a school gym. NOTE: I am NOT going to attempting to rig it myself. I AM NOT a professional rigger. that said i will be hiring a professional rigger.what i would like to know is how do i approach this task. How do i find/locate a quality rigger? google searches keep turning up results for crane operation riggers? what equipment should i buy or rent gig by gig in order to do this? Etc. Etc. Any Information would be incredibly useful.

Thanks In Advance,
JL Griffin
CEO of CG Entertainment

Where are you located?

Use the following link to find the nearest IATSE local.  They will hook you up with a rigger.  You will need a man lift to get to the gym steel.


http://www.iatse-intl.org/directory/search.asp
Title: Re: SOP for overhead trussing?
Post by: Brian Ehlers on August 26, 2011, 12:55:02 pm
I'd like to ask a related question:

If no design or load ratings for the existing structure are known, how will (or should) the rigger approach the job?  How does a rigger evaluate whether or not the structure is adequate for the load to be suspended?  At what point does he call in a structural engineer before completing the rigging?
Title: Re: SOP for overhead trussing?
Post by: John Livings on August 26, 2011, 09:26:39 pm
I'd like to ask a related question:

If no design or load ratings for the existing structure are known, how will (or should) the rigger approach the job?  How does a rigger evaluate whether or not the structure is adequate for the load to be suspended?  At what point does he call in a structural engineer before completing the rigging?

Brian, The simple is answer is without a structural assessment you don't know.

The design load of the trusses or beams may already be exceeded. (everyone keeps adding equipment, AC and other heavy things)

It is possible an assessment has already been done (As far as hanging equipment) during the building planing stage of construction.

If it is an old school, that information may not be available.

A lot of things get "bootlegged" in without any problems, However I would recommend NEVER doing this or be part of doing this.

I really don't even know how many spaces we have worked in that someone opened up 2  or 3 spaces to create 1 large space.

They determined the "Partition" walls were "Non Bearing" and removed them only to find out that they removed  "Engineered Sheer" Walls.

This is how rectangles become parallelograms

Almost always more expensive to fix than to have done it correctly in the first place. (by a factor of 2X or 3X more).

Just my thoughts.

Regards,  John

To answer the OP question, I am guessing your goal is not to just hang a piece of truss.

What is the load that will be hung from the truss, Lights, Wires, Speakers???

The problem as I see it is not having someone (Structural Engineer)  with the Global  Picture putting all the pieces together.
Title: Re: SOP for overhead trussing?
Post by: John Louis Griffin on August 27, 2011, 12:11:12 pm
@ John Livings

Well I  am trying to hang 2 trusses. 1 will be above the dj stand and will be a 16 foot segment of triangular trussing. from it will be suspended 20 custom built line arrays (10 on each side) 4 chauvet intimidator scanners and 2 chauvet min spots. then over the crowd i plan to suspend a circle of triangular trussing 18 feet in diameter and from it suspend 8 Chauvet Intimidator LED spots and 8 Chauvet COLORstrip Minis as well as 4 Chauvet Techno strobe LEDs and 4 Chauvet led shadow (Blacklight) panels. in the center of the circle will be a piece of x shaped trussing where each leg of the x is 2 feet long, and from it will be suspended an american dj Spherion Tri led.

Hope this helps,
JL Griffin
Title: Re: SOP for overhead trussing?
Post by: James Feenstra on August 27, 2011, 01:38:32 pm
10 boxes of any line array will generally be in at least the 800-1000lb range, so i'd definitely want to get a structural engineer involved to find out if the roof can actually support the weight of that where you want to hang it

first thing you'll want to do is tally up the weight of everything you want to hang (truss, lights, speakers, chainfalls, motors, etc), add 20% for cable/misc rigging and add another 20% of that on top for a safety factor, then ask the engineer if the roof can support the weight

it'd be even better to have a cad/wysiwyg drawing of what you're hanging with weights per point written on it so the engineer can approve it

you're looking at somewhere around 6 points (2 for your 16' truss, and 4 for the circle) plus cable pics...I wouldn't hang it with less

you really do need to check with an engineer though before doing anything!
Title: Re: SOP for overhead trussing?
Post by: John Louis Griffin on August 27, 2011, 05:51:38 pm
@ James

Yeah I Plan to talk to a structural engineer about all of this. For this kind of thing im ready to pull out all the stops. Its just not worth the risk of having it done wrong. People's Lives are at stake when you start hanging stuff over their heads. a 5lb lamp could fall and kill someone. thats why i posted this. i want to make sure i have all the points covered before i do anything, including the ones i havent thought of.

Thanks for the tip about wysiwyg/cad. i hadnt actually thought to do something like that. i have a friend who is good with cad stuff so i can have him help me with an initial plan.

Thanks for the help and advice. It's very much appreciated.

-JL
Title: Re: SOP for overhead trussing?
Post by: Mac Kerr on August 27, 2011, 06:29:27 pm
@ James

-JL

Please go to your profile and change the "Name" field to your real full name as required by the posting rules clearly displayed in the header at the top of the section, and in the Site Rules and Suggestions (http://forums.prosoundweb.com/index.php/board,36.0.html) in the Forum Announcements section, and on the registration page when you registered.

Mac