Theater Rigging - Engineer Seal/Sign?
Theater Rigging - Engineer Seal/Sign?
(OP)
I have a client who designs, fabricates and supplies theater rigging (pulleys, ropes, curtains, etc.) for theaters.
They are doing a project where the theater consultant is requiring their rigging shop drawings to be sealed by a structural engineer. It is listed in the project specs that this is a requirement.
The question I have is that I'm not sure this is really valid (requiring a seal). The structure of the theater itself (the roof, beams, etc.) have all been designed by the building EOR to support the rigging. The rigging itslelf isn't a "structure" but rather a proprietary product made up of pulleys, cables, controls, counterweights, etc.
A structural engineer like myself typically doesn't have the experience to seal "equipment" like this.
The rigging is warranted, certified by the supplier, etc. as a functioning, and guaranteed product.
Is the theater consultant off base here? Most states don't allow an engineer to "review" a shop drawing and seal it (plan stamping).
They are doing a project where the theater consultant is requiring their rigging shop drawings to be sealed by a structural engineer. It is listed in the project specs that this is a requirement.
The question I have is that I'm not sure this is really valid (requiring a seal). The structure of the theater itself (the roof, beams, etc.) have all been designed by the building EOR to support the rigging. The rigging itslelf isn't a "structure" but rather a proprietary product made up of pulleys, cables, controls, counterweights, etc.
A structural engineer like myself typically doesn't have the experience to seal "equipment" like this.
The rigging is warranted, certified by the supplier, etc. as a functioning, and guaranteed product.
Is the theater consultant off base here? Most states don't allow an engineer to "review" a shop drawing and seal it (plan stamping).






RE: Theater Rigging - Engineer Seal/Sign?
Stick to your guns here. They are trying to pass the buck.
Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask
RE: Theater Rigging - Engineer Seal/Sign?
RE: Theater Rigging - Engineer Seal/Sign?
Another reason not to sleep at night in this profession.
RE: Theater Rigging - Engineer Seal/Sign?
Love your handle - you're not into forensics are you? If you haven't already, you should really meet Ron.
Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask
RE: Theater Rigging - Engineer Seal/Sign?
Another thought here - what does your contract say to any design limitations, or requirements?
Also, I use a "shop stamp" for the shop drawings, never, but never a seal. I also only shop review what I have either reviewed with my own supplemental calculations, or specifically designed myself.
This request is tanamount to a structural stamp for a desk or moveable partition system designed by others to rest on a structural floor. Sorry, but from my perspective, it makes no sense.
Tell the client to have the supplier furnish the documentation he needs for the products. You have not designed them and cannot attest to their structural integrity.
Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask
RE: Theater Rigging - Engineer Seal/Sign?
RE: Theater Rigging - Engineer Seal/Sign?
The EOR of the building designed the roof structure to support the rigging.
The theater consultant (working with the AOR and EOR) wrote the specification for the rigging and in that spec requires a licensed engineer to seal the shop drawings of the rigging.
The contractor bid the job using a rigging sub-contractor.
The rigging sub-contractor submitted shop dwgs without an engineer seal.
The Architect rejected the shop drawings since they didn't have a seal.
The rigging sub is now looking to us to seal the shop drawings but the question I posed above is: Is the seal on the shop drawings really warranted since this is a PRODUCT and not a BUILDING design.
Products are usually warranted, not sealed by an engineer.
And the other question I have is: Is the requirement for sealing rigging shop drawings a typical thing? A current thing? A future thing that's coming more prevalent?
RE: Theater Rigging - Engineer Seal/Sign?
And, I assume this is something that is normally exempt due to industry exemptions (a manufactured item), but they are wanting a PE seal anyway?
If the work isn't obviously "structural" in nature, the consultant would probably accept a PE seal from other appropriate disciplines.
It might be worthwhile to ask that consultant if a review of the material would be acceptable as an alternative to sealing the material. That is, you can review their material, write up a brief report indicating that is or isn't okay as far as you see, and seal that report.
Keep in mind that when you get into weird stuff, there may not be anyone else better qualified to design it, either.
RE: Theater Rigging - Engineer Seal/Sign?
As for the "requirement", certainly not when I did my project. I guess you can ask for anything though in the world today. Getting it's another story. Look to the contract. If you were doing the building design, it would fall under the auspices of the IBC. Not so the rigging, etc.
Contractually, though, if this "requirement" was in the contract or specd/job description prior to you agreeing to the contract, you may be on the hook.
Considering everyone wants to pass the buck nowadays for lisability, I am not surprised they want a larger pocket available.
Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask
RE: Theater Rigging - Engineer Seal/Sign?
I would assume in this situation you would make sure cables are properly sized, chainfalls, and whatever else may come with it. Analyze beams that the chainfalls are attached to.
RE: Theater Rigging - Engineer Seal/Sign?
Mike, this isn't a shop drawing stamp we're concerned about. The design professional of the building would use that. We are being asked by a sub-contractor to review their rigging design and seal their component of the structure.
Thanks for the replies so far - keep them coming if you have other thoughts.
RE: Theater Rigging - Engineer Seal/Sign?
The Architect/Engineer & Owner considered this portion of the work to be the equivalent to a "Design-Build" specialty contract. The A/E was not required to seal these drawings/documents.
www.SlideRuleEra.net![[idea] idea](https://www.tipmaster.com/images/idea.gif)
www.VacuumTubeEra.net
RE: Theater Rigging - Engineer Seal/Sign?
RE: Theater Rigging - Engineer Seal/Sign?
Ok. "We are being asked by a sub-contractor to review their rigging design and seal their component of the structure."
I guess that I am a little confused here as to what is meant by the "rigging design". Are you talking about the specific layout ot the rigging, that it provides the specified mechanical advantage for manual lifting of a certain load? Or are you talking the actual structural design of the pulleus and blocks? Or something else?
Is this something that you feel comfortable doing? If you are not comfortable with it, don't do it.
I can see that there is obviously structural design in this, but a bit out of the ordinary. More specialized.
Again, do you have to sign off on the actual structural design of the block and tackle, calculations provided by others, or only the rated capacity of the specific off-the-shelf equipment provided by the supplier - that it can lift the loads of the specs?
Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask
RE: Theater Rigging - Engineer Seal/Sign?
http:
www.SlideRuleEra.net![[idea] idea](https://www.tipmaster.com/images/idea.gif)
www.VacuumTubeEra.net
RE: Theater Rigging - Engineer Seal/Sign?
Mike Halloran
Pembroke Pines, FL, USA
RE: Theater Rigging - Engineer Seal/Sign?
msquared48: The rigging we're looking at is a series of pulleys (blocks), cables, counterweights, knee braces to walls, and connections of these items to the structural beams overhead and the walls. The pulleys, or blocks, are manufactured items. Cables are aircraft type cabling (7 strand).
You are absolutely right that this is a very specialized area. There is some discomfort for us but at the same time, while it looks complex, it's really quite simple really.
Mike Halloran: The weird thing here is that the design team for the building is asking a very experienced rigging contractor to go get a structural engineer to sign off on their rigging when most all structural engineers don't know much about rigging. Seems like someone is just trying to check off a box somewhere and feel like they are improving safety and quality.
RE: Theater Rigging - Engineer Seal/Sign?
We have several theaters in our office right now, I will ask a senior engineer about this issue tomorrow, and how it has been handled in the past.
RE: Theater Rigging - Engineer Seal/Sign?
I see no problem with this if you can justify the design to yourself.
And you get paid an appropriate fee.
DaveAtkins
RE: Theater Rigging - Engineer Seal/Sign?
About 10 years ago we did a rigging analysis for the PAT/Field Goal net for the Jax Jaguars that is cable supported. It was truly a structural function with some "machine" implementation. Was it mechanical? Was it structural? Well...a little of both. Fuzzy area.
I have two clients for whom I do analysis of their "designs" and I sign and seal shop drawings. One of them produces custom structures and the other produces stairs and rails (somewhat a "product"). My condition on all of this is that if I ask for a design modification, it has to be done. If I ask for a change in the drawings (notations, spelling, format) it has to be done. When the drawing matches my analysis, I'll sign and seal it....otherwise, no dice. For one of these clients it has worked well for 25 years. For the other, I'm into my 2nd year and so far, so good. I will not do a shop drawing "review" and sign and seal it. I do calculations on every one that I sign and seal. Sometimes the calcs are just rudimentary checks on repetitive items...I have to do enough that I feel comfortable answering questions about them, in the event I'm asked.
RE: Theater Rigging - Engineer Seal/Sign?
ASME BTH isn't applicable, but is a good example of what goes on. It's an ASME document, therefore it should be ME specifically, but then all the design equations are right out of AISC-05.
Past experience with the field would help largely to know if there were any standards applicable to it. You could conceivably have building code or OSHA rules relating to it. Possibly fire considerations as well.
RE: Theater Rigging - Engineer Seal/Sign?
For you to sign and seal the shop drawings you will have to be able to show via calculations that it works. I'd charge by the hour since there isn't anyway of knowing how long it will take. I'd tell them take it or leave it. I'd think you'd be able to find load ratings for the individual components such as the pulleys, ropes, chains, etc... On your calculations and/or shop drawings you could qualify that things such as curtains haven't been designed. Just make sure the client knows it will costs alot.
Don't shout in this in the theater (I mean Florida) or pretty soon they will be requiring Florida Product Approval. Of course that might be nice since it would be a one time design.
Thanks for bringing this topic up. For years I have tried, and always failed, do be able to get anyone to tell me the weight of the rigging over stages. So I've always overdesigned the roof and beams like crazy.
John Southard, M.S., P.E.
http://www.pdhlibrary.com
RE: Theater Rigging - Engineer Seal/Sign?
As a structural engineer these are all elementary calculations, but the fact that you are supporting things from a building your SPECIFIC area of practice would help further. I would have a pretty simple analyzation of the beam, where some of you structural engineer would get pretty detailed into it.
RE: Theater Rigging - Engineer Seal/Sign?
Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask
RE: Theater Rigging - Engineer Seal/Sign?
As long as you think is proper of you making such kind of work and they pay enough, spend the necessary time and let them know that this is never to be a matter to pass you the liability without proper review. If, on the other hand, it is some kind of standard product, I think it unusual the provider is not delivering it with a proper warranty of it, even installed, except that by being mean on them they have not payed them for reviewing that their design is in accord with their specs. Or they are being astute, providing a design without signing it, if something happens, they are not the structural designers (this may be the case) but are merely selling parts (not that uncommon, in the micropile -or prefab- field they are more experienced, provide the alternative design, come to show what they do with structural design very acquainted with the thing, sell the standard products, do and to some extent control the installation by themselves and yet... the architect must approve and sign the works, they are NOT signing what they are selling and providing even if they have more experience in the field).
If the contractor have allowed them such easygoing entry in the work, must not be surprised that there was a cost that he had not counted on; furthermore, since the system would be propietary, I still feel the one making the review, to keep them in the hook in spite of any reviews one makes, ask that they certify the quality, the behaviour and workmanship of anything that they provide in accord to their "propietary" (but who knows if deceivingly unwarranted) product design. For if it can be thought as a product will come under different rules and they must both warrant the product and, for one thing like this, the standard installation, or that has had an installation according to their standard.
RE: Theater Rigging - Engineer Seal/Sign?
What did the spec say for the rigging? We usually specify what items require a seal. If it wasn't in the spec, then I don't know how it can be required at this stage (pun unintended)
"Is the requirement for sealing rigging shop drawings a typical thing? A current thing? A future thing that's coming more prevalent?"
For something out of the ordinary, yeah, rigging maybe, but could be a slippery slope. Do drop ceilings need a seal? chandaliers, art pieces, HVAC components etc....
RE: Theater Rigging - Engineer Seal/Sign?
RE: Theater Rigging - Engineer Seal/Sign?
RE: Theater Rigging - Engineer Seal/Sign?
The engineering seal requirement has been around and growing for about the last 5-7 years. It seems apparent that specilty equipment specifiers often are not registered design professionals and shift liability in this manner. However, in practice it is appropriate to have such things checked by an engineer experienced in this specialty discipline, because even structures specifically built for performance can be introduced to new or increased loading conditions for which it may not have been originally designed. We also see this frequently in renovation projects. Hope this helps.
Entertainment Structures Group
RE: Theater Rigging - Engineer Seal/Sign?
Richard A. Cornelius, P.E.
WWW.amlinereast.com
RE: Theater Rigging - Engineer Seal/Sign?
When an Engineer seals a document there is an implicit certification that she is qualified in that discipline. An engineer with the appropriate learning and experience should seal the documents.
Michael.
Timing has a lot to do with the outcome of a rain dance.
RE: Theater Rigging - Engineer Seal/Sign?
In your case you would need to determine the load on each component and ensure that it has adequate capacity. I would think that you would also need to determine the load that will be applied to the buiding structure and ensure that it is less than that for which the building was designed to handle as you mentioned in your OP.