Help with ideas for steeply raked stage (sculpture).

Hello everyone,

First, I hope that my presence here isn't too out of line as I work in a museum and not a theater. Much of my work overlaps the theater knowledge set and I have worked in theaters before. I am in charge of all fabrication at my museum and I'm looking to hear some ideas and pros/cons for an upcoming art installation.

So, given that this fabrication is for a video artist's install, the typical concerns about rake slope and performer safety aren't really applicable. Safety is still my top priority, but it will be visitor safety. In the photos, you can hopefully see a raked stage of sorts that has a carpeted stage on top for viewers to climb up into/on and watch half of the piece's contents and a second area similar to a trap room where they can watch a second video.

I have been asked to come up with ways to build this structure that are 1) Safe 2) Aesthetically pleasing (underside) 3)Fast and of course 4) Budget friendly. I raise an eyebrow every time someone asks for 'good, fast, cheap'. In any case, I'd love to hear your thoughts. I'm comfortable doing a traditional wooden truss construction, perhaps going with aluminum I beams and supports, maybe the pipe method in these photos (from a previous run of the work.) Trying to find the goldilocks method/material.
 

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BillConnerFASTC

Well-Known Member
If this is an exhibit open to the public, it can be no steeper than 1:8. And steeper than 1:12 risks running afoul of federal and other laws for accessibility. Unguarded fall hazards seem to also not be addressed. "Art" does not get a pass for egress and accessibility.
 
If this is an exhibit open to the public, it can be no steeper than 1:8. And steeper than 1:12 risks running afoul of federal and other laws for accessibility. Unguarded fall hazards seem to also not be addressed. "Art" does not get a pass for egress and accessibility.

Thank you for the reply. In a way, it is different as art and we do get a bit more freedom. This is an interactive sculpture. It has been installed at previous museums at the slope shown in the photos. We are aware of the accessibility issues and will likely have to produce language for that shortcoming, as the artist will not compromise on that aspect and our space isn't large enough to do a lower slope a still produce a walkable under stage area. Regarding the handrails/edges, I am going to advocate for having rails installed on all edges that don't contact a wall. It looks like this install my not of have done that.

Those details aside, I am curious about how other fabricators may tackle the support structure. The surface area of the sloped plane is 36' x 18' and currently my main concern is supporting the weight of the stage and guests but still keeping the underside free enough from structure to allow for movement below.
 

BillConnerFASTC

Well-Known Member
I'd guess a stressed skin about 5" thick spanning the 18' dimension would do it. Maybe 6". A bit of engineering. But do have to support long edges.
 
So, I know tone is hard in written form, so know that I say this with a big smile but also concerned eyebrows. You guys wouldn't *believe* the stuff that gets through/approved 'because its art.' The one time I've had to get an engineer involved was when we hung a 26,000 lb sculpture in our atrium space. Ya, 13 tons over the public's head, I'm not rigging that without a stamp!

I'm pretty sure given the tone of this project that I'll be asked to 'get er done' on my own. I always overbuild when it is an interactive work or one that supports visitors. I'm just trying to crowdsource ideas for the vertical/undercarriage support structure. I appreciate the ideas. Gluelam would be nice for the long spans, I don't know if it is within our budget but I can always make a case for it. I think I'm also moving away from my initial thoughts of doing studwalls underneath, I may try to fiddle with some post support structure similar to outdoor decks.

One additional thing that may help with ideas, I think I can convince the artist to let me have one of the long angled sides butt to a wall, so I can mount a ledger board.

Thank you both again. I'm always welcome to more/new ideas.
 

TimMc

Well-Known Member
Premium Member
So, I know tone is hard in written form, so know that I say this with a big smile but also concerned eyebrows. You guys wouldn't *believe* the stuff that gets through/approved 'because its art.' The one time I've had to get an engineer involved was when we hung a 26,000 lb sculpture in our atrium space. Ya, 13 tons over the public's head, I'm not rigging that without a stamp!

I'm pretty sure given the tone of this project that I'll be asked to 'get er done' on my own. I always overbuild when it is an interactive work or one that supports visitors. I'm just trying to crowdsource ideas for the vertical/undercarriage support structure. I appreciate the ideas. Gluelam would be nice for the long spans, I don't know if it is within our budget but I can always make a case for it. I think I'm also moving away from my initial thoughts of doing studwalls underneath, I may try to fiddle with some post support structure similar to outdoor decks.

One additional thing that may help with ideas, I think I can convince the artist to let me have one of the long angled sides butt to a wall, so I can mount a ledger board.

Thank you both again. I'm always welcome to more/new ideas.
If you don't have the budget to build it safely, you don't have the budget to settle the wrongful death and personal injury claims. The people that "approve" silly shite without engineering approvals should be personally liable for making whole the families of deceased and the injured prior to any insurance coverage paying out.
 
I'm trying to be upbeat and positive here, just thought I'd talk fab with some other builders but it seems many people here have a very reactionary and bellicose attitude towards others.

I never said we don't have money to build it safely, I mentioned that we may not have the budget for gluelam, if you think that one product is the only way to build a span safely, you're wrong.

I've built homes, decks, and stages for decades. You certainly do *not* need to waste money on a wetstamp for every project. When it *is* needed, I get it.

If you or anyone else would like to share thoughts and feedback on construction, I'd be happy to chew the fat and bounce ideas, but I didn't sign up just to have my professionalism, judgement, and craftsmanship questioned by internet superheroes.
 

kicknargel

Well-Known Member
I don't mean in any way to be disrespectful. You're probably a well-seasoned pro who can safely construct this thing. As am I. My first thought was, "I'd start with 'Structural Design for the Stage' by Alys Holden and Ben Sammler." Then I thought, "There's some beam and column calculations I wouldn't be confident about; pretty sure I'd want to get double-checked by an engineer, especially given that it's public access." Then I thought, "What about egress? Tricky. The head-height thing is a thing also. I'm pretty sure this should be permitted; at least an event permit." If I were asked to build it I would do those things. I've project managed haunted houses and music festivals. We do those things. It's not that difficult or expensive.

We all do risk analysis. Nothing is fully safe. But the pros in the field exercise an abundance of caution because you have to be way-too-safe to drive the accident rate down far enough for our taste. People can and do get away with all kinds of stuff that's totally fine 9,999 out of 10,000. But the 10,000th time someone dies in a preventable way.

So, if asked to do this project I would get a stamp and a permit. Otherwise I wouldn't do it. And therefor I won't give advice about it over the internet. You're probably totally capable (how would I know?) and I hope if it goes, it goes great.
 

TimMc

Well-Known Member
Premium Member
I'm trying to be upbeat and positive here, just thought I'd talk fab with some other builders but it seems many people here have a very reactionary and bellicose attitude towards others.

I never said we don't have money to build it safely, I mentioned that we may not have the budget for gluelam, if you think that one product is the only way to build a span safely, you're wrong.

I've built homes, decks, and stages for decades. You certainly do *not* need to waste money on a wetstamp for every project. When it *is* needed, I get it.

If you or anyone else would like to share thoughts and feedback on construction, I'd be happy to chew the fat and bounce ideas, but I didn't sign up just to have my professionalism, judgement, and craftsmanship questioned by internet superheroes.
I'm not questioning your professionalism or building abilities. I'm speaking of higher up in the food chain. I'm also speaking to individual responsibility and the ethics of failing to provide the best possible work (design, materials, practices) to minimize the chances of a failure that could result in deaths or injuries.

Laminated beams are one solution and I'm sure that there are others... and I'm certain that in the event of a failure anyone who could be quoted as over-ruling advice to build something stronger or with better engineering will be painted with a big, tarry brush at the civil trial.

{general statement} Theater is largely a transient and temporary thing. We're not building bridges over rivers or office towers expected to last 50 years or more but that does not mean *we* are off the hook for a build that isn't up to the task of safety. The mentality of building sets or platforms or pit covers that are "just good enough to last to the final performance" isn't good enough for me. Others have different standards and constraints and my only input is to warn others of potential liability for decisions that would be better reviewed by professionals. {/general statement}
 
I'm definitely not saying 'art' is an excuse to create a hazard.
I'm simply looking for advice from other builders and also mentioning that at our institution, we do not typically get permits for builds unless they are egregiously dangerous. And in my museum experience, this seems to be par for the course; hence why I always try to overbuild for safety.

@TimMc I fully agree that the temporary nature isn't an excuse to under-build. I just completed a wall for our current show that is 26' L x 16' high with an outward lean over the audience of 15 degrees. I insisted that we rig a system of anchors and redundant support cables that made the CFO's eyes roll.

So, that said, I am curious about a specific thing. Have either of you used aluminum I-beams? I also have the unfortunate constraint about worrying about floor load psi as this is on a second floor. I'm curious how the strength/weight/cost/ease of use is on those. I've never had occasion to build with them.
 

BillConnerFASTC

Well-Known Member
I have designed with aluminum framing. About half the weight at triple the price of steel.

Foam and plywood or small members and plywood using stressed skin engineering is bound to be the lightest and least expensive. You have to have good engineering and pay strict attention to details, but not much more difficult than good carpentry. That can solve the structural and weight. It doesn't address the egress issues in terms of slope, head clearance, fall hazards, etc.
 
Thank you for the info.
I am planning on the deck being 48"x48"x3" stressed skins (at least at this point in planning).
The spans and vertical supports are the fat I'm chewing. Thanks again. I'll have to price the aluminum vs. steel vs. doug fir.
 

BillConnerFASTC

Well-Known Member
I don't know how big over all but I mean build one deck all stressed skin, no framing, except at edges. You can easily span 16-20 feet or more with a stressed skin panel. I worked on a 16' that was only 4 or 5 inches thick.
 
I'd love so see any shots of the build you have, to see if we're doing joinery in different ways and to take a look at the seams. Ya, I think doing stressed skin will help with many of the concerns, I have to do a weight calc to see how much I have left after that for the substructure.
 

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