ProSoundWeb Community

Please login or register.

Login with username, password and session length
Advanced search  

Pages: [1] 2 3 ... 7   Go Down

Author Topic: Question for the rigging experts.  (Read 31784 times)

Robert "VOiD" Caprio

  • Full Member
  • ***
  • Offline Offline
  • Posts: 182
  • Long Island, NY
    • Interzone Studios
Question for the rigging experts.
« on: March 19, 2012, 07:49:13 pm »

Hey guys and gals,

Need to hang two JBL VRX932 speakers per side from ceiling truss in a venue.   Our structural guy has approved the weight.  The truss has two L shaped spans at the bottom of it running the width of the room.  The space between the spans is about half an inch.  I've attached pics for detail.  I have experience with rigging over round truss with span sets and all that but have never dealt with this type of thing so I need your expertise.

Thanks.
Logged
FOH/MON/REC/MIX Engineer/Producer/TM/RF Tech
Currently mixing MON for Boston
www.interzonestudios.com
void at interzonestudios dot com

Tim McCulloch

  • SR Forums
  • Hero Member
  • *
  • Offline Offline
  • Posts: 20857
  • Wichita, Kansas USA
Re: Question for the rigging experts.
« Reply #1 on: March 19, 2012, 07:57:27 pm »

Hey guys and gals,

Need to hang two JBL VRX932 speakers per side from ceiling truss in a venue.   Our structural guy has approved the weight.  The truss has two L shaped spans at the bottom of it running the width of the room.  The space between the spans is about half an inch.  I've attached pics for detail.  I have experience with rigging over round truss with span sets and all that but have never dealt with this type of thing so I need your expertise.

Thanks.

Temporary or permanent install?
Logged
"Practicing an art, no matter how well or badly, is a way to make your soul grow, for heaven's sake. Sing in the shower. Dance to the radio. Tell stories. Write a poem to a friend, even a lousy poem. Do it as well as you possible can. You will get an enormous reward. You will have created something."  - Kurt Vonnegut

Robert "VOiD" Caprio

  • Full Member
  • ***
  • Offline Offline
  • Posts: 182
  • Long Island, NY
    • Interzone Studios
Re: Question for the rigging experts.
« Reply #2 on: March 19, 2012, 07:58:27 pm »

Temporary or permanent install?


Permanent.
Logged
FOH/MON/REC/MIX Engineer/Producer/TM/RF Tech
Currently mixing MON for Boston
www.interzonestudios.com
void at interzonestudios dot com

RYAN LOUDMUSIC JENKINS

  • Hero Member
  • *****
  • Offline Offline
  • Posts: 597
    • Az Concert Sound Solutions
Re: Question for the rigging experts.
« Reply #3 on: March 19, 2012, 08:04:34 pm »


Permanent.

I am no rigging expert but would an I-Beam clamp not work?  Have you asked you structural guy about that?  In the back of my head I am thinking that a structural engineer should sign off on what ever goes there.
Logged

Tim McCulloch

  • SR Forums
  • Hero Member
  • *
  • Offline Offline
  • Posts: 20857
  • Wichita, Kansas USA
Re: Question for the rigging experts.
« Reply #4 on: March 19, 2012, 08:28:46 pm »


Permanent.

Attached to the main truss or bridge truss?  They will have different ratings and loading point specifications.

Bear in mind that superior point loads are *generally* attached near a node, typically the lower diagonal panel joint.

I'm with Ryan, your structural guy needs to specify the materials and methods to be used to attach the load to the truss chord as well as the placement of those loads.  You may need to provide additional load bearing structure to span between main or bridging truss to get speaker placement exact.  This needs to be detailed in engineering drawings and approved/stamped by a RPE.
Logged
"Practicing an art, no matter how well or badly, is a way to make your soul grow, for heaven's sake. Sing in the shower. Dance to the radio. Tell stories. Write a poem to a friend, even a lousy poem. Do it as well as you possible can. You will get an enormous reward. You will have created something."  - Kurt Vonnegut

Bill Hinds

  • Jr. Member
  • **
  • Offline Offline
  • Posts: 67
Re: Question for the rigging experts.
« Reply #5 on: March 19, 2012, 10:25:34 pm »

I am no rigging expert but would an I-Beam clamp not work?  Have you asked you structural guy about that?  In the back of my head I am thinking that a structural engineer should sign off on what ever goes there.


I am not an expert but we just had a project very similar to this.  I have been told by a Structural Engineer that an I Beam clamp is not acceptable for use on that type of truss shown in the picture.  I believe it is called K Truss or Open Web truss. Make sure the Structural Engineer signs off but it will most probably will have to go over the top or bottom cord with Grade 100 Chain and will have to be almost right over where the where the panel points come together to form a V.  Also, if going over the Top Cord, is the joist a flat roof or does it have an angled pitch to it?  If it is pitched it will have to have a way to ensure the chain is not able to "slide" down the joist and get wedged in the corrugated roof as it can damage the roof structure.

NOTE:  I am NOT a Structural Engineer so DO NOT take my word for it.  I also suggest you call Polar Focus and show them what you have.  They can design something with a drawing that the Structural Engineer can stamp his approval on or decline.
« Last Edit: March 19, 2012, 10:33:32 pm by Bill Hinds »
Logged

Jim McKeveny

  • Hero Member
  • *****
  • Offline Offline
  • Posts: 1080
Re: Question for the rigging experts.
« Reply #6 on: March 20, 2012, 08:02:09 am »

Again, I am contrary.....2 x VRX932 is under 100 lbs. load. In most jurisdictions this gives you broad leeway regarding safe overhead installation. In similar situations I have used forged eyenuts with appropriate length SAE grade 5+ bolts & HD steel washers to establish points at the truss gap. Add a safety loop of aircraft cable & jam-nut the bolt and you are good for 100 years (barring quake + tsunami. The lights will come down first anyway)..

McMaster/MSC is your friend.
« Last Edit: March 20, 2012, 08:05:32 am by Jim McKeveny »
Logged

Andrew Welker

  • Church and H.O.W. Forums
  • Newbie
  • *
  • Offline Offline
  • Posts: 22
  • Denver, CO USA
Re: Question for the rigging experts.
« Reply #7 on: March 20, 2012, 10:23:49 am »

Hey guys and gals,

Need to hang two JBL VRX932 speakers per side from ceiling truss in a venue.   Our structural guy has approved the weight.  The truss has two L shaped spans at the bottom of it running the width of the room.  The space between the spans is about half an inch.  I've attached pics for detail.  I have experience with rigging over round truss with span sets and all that but have never dealt with this type of thing so I need your expertise.

Thanks.

In situations like this, I would typically span 1-5/8" unistrut between 2 of the main beams using beam clamps, then use forged eyebolts into strut nuts to get my points. You can space the strut whatever distance you would like so that the wire rope/chain is hanging straight down.
Logged

Tim McCulloch

  • SR Forums
  • Hero Member
  • *
  • Offline Offline
  • Posts: 20857
  • Wichita, Kansas USA
Re: Question for the rigging experts.
« Reply #8 on: March 20, 2012, 10:53:24 am »

In situations like this, I would typically span 1-5/8" unistrut between 2 of the main beams using beam clamps, then use forged eyebolts into strut nuts to get my points. You can space the strut whatever distance you would like so that the wire rope/chain is hanging straight down.

This is the type of thing I'd expect to see from the structural engineer, but called out on a print with his/her stamp on it.

This is also the kind of specific advice I would not give on a public forum.  Not because Void will take shortcuts (he wont), but because someone else will read this a month/year from now and assume it is all he needs to know.
Logged
"Practicing an art, no matter how well or badly, is a way to make your soul grow, for heaven's sake. Sing in the shower. Dance to the radio. Tell stories. Write a poem to a friend, even a lousy poem. Do it as well as you possible can. You will get an enormous reward. You will have created something."  - Kurt Vonnegut

Jim McKeveny

  • Hero Member
  • *****
  • Offline Offline
  • Posts: 1080
Re: Question for the rigging experts.
« Reply #9 on: March 20, 2012, 12:02:56 pm »

When you hear hoofsteps, think horses not zebras. THE LOAD INSN'T THAT GREAT. Engineers tend to go too far into "best way", and overthink/overprice what is really needed. I would seat my children under the method I described now & 25 years from now.

Logged

ProSoundWeb Community

Re: Question for the rigging experts.
« Reply #9 on: March 20, 2012, 12:02:56 pm »


Pages: [1] 2 3 ... 7   Go Up
 



Page created in 0.041 seconds with 22 queries.