I am an architect working on a project where we're construction an air-supported structure (dome) for a school district to use as their physical education gymnasium.
The fire marshal here wants the dome fire suppressed. I told him we cannot hang water piping from the dome. What are the options to provide fire suppression inside of a air supported structure that is 180 x 135 feet? Are there alternatives, like water cannons along the perimeter? If so, what kind of costs might that suggest? Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe
25 Comments
Franck
10/10/2022 08:46:49 am
That could be problematic for the students ;)
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matt
10/10/2022 08:19:15 am
Can the structure be deflated/turned off? What happens if the air is turned off?
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Ralph Giro
10/10/2022 08:25:56 am
There is usually a metal framing system to help hold the fabric in place. I would start by consulting with the supplier of the fabric dome material to get their suggestions. This is not uncommon.
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Questions:
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Glenn Berger
10/10/2022 08:39:28 am
You will need to work with the AHJ on this one. Provide fire suppression in the dome will not happen. But, fire protection would be required in the supporting areas.
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Todd Wyatt
10/10/2022 08:46:43 am
You state that the “fire marshal here wants the dome fire suppressed.” An authority having jurisdiction (AHJ) are required to enforce and interpret the adopted Codes, they are not permitted to require Projects to be protected with an automatic sprinkler system (ASPS) because they “want” it unless the Code requires it.
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Todd E Wyatt
10/10/2022 08:51:13 am
180 feet x 135 feet = 24,300 SF > 12,000 SF
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Franck
10/10/2022 08:52:47 am
As Glenn indicated, it would be more than problematic to provide a water-based fire protection system inside, for several reasons:
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Greg
10/10/2022 09:22:05 am
One of the ways to explain to the Fire Marshal why sprinklers are complicated in this scenario is the tent material, the suppression angles and the height. Sprinklers are designed to operate within the jet plume of a fire, but the angle presented by the walls of dome create a more likely scenario where the fire will challenge the dome's fabric material ahead of sprinkler activations. This, in combination with the angles needed to suppress with traditional sprinklers make their presence in approximately 2/3rds of the tent impractical. For the 'ceiling' area, the remaining 1/3 is typically too high for the anticipated combustible load to anticipate the jet plume will come near enough to activate the sprinklers. They are likely published studies with similar rational, funded for evaluation of government use of such structures. There is manufacturer who has a water cannon pictured as part of their advertisement, in Arizona https://arizonbuildingsystems.com/wp-content/uploads/2016/09/Fire-Protection-Systems-in-Air-Structures.pdf This was a study of sprung structures, government funded. https://www.osti.gov/biblio/801337 Air supported structure challenges the conclusion reached in the sprung study, but it's the information within the report that is important in this conversation.
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Alex
10/10/2022 11:29:40 am
Hi,
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Jesse
10/10/2022 12:12:47 pm
This one has me stumped. I've been a part of many of these types of projects and I don't recall AS protection being a part of ay them.
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Connor
10/10/2022 12:39:57 pm
Another consideration is the flexibility and movement of the fabric dome structure. If it were somehow possible to hang the pipe in the first place, the flex of the dome could deform the piping or even cause it to come apart. I would imagine the hazard presented by 3" pipe and fittings falling on a soccer field would warrant consideration.
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Dan Wilder
10/10/2022 01:08:09 pm
We've completed one of these is the past with a mix of fixed and manually elevated water powered oscillating monitor nozzle towers, typically in 6 locations (corners and center edges) with a manual override. We did provide sprinkler protection in the connecting egress tunnels (they had a metal scaffold like framework).
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Shahpoor Khosravi
10/10/2022 03:34:35 pm
In case you cannot convince the AHJ that the sprinkler is not needed, my suggestion would be to provide monitors with beam detection systems so you would not need to hang pipes from the structure.
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Brian Cockburn
10/11/2022 09:47:20 am
Even if it's possible to hang sprinkler pipe from the dome; what happens when the dome is deflated for maintenance, or there's a power outage, or the blowers fail?
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10/11/2022 10:00:52 am
The Convention center in Pittsburg uses a "soft" roof. Their solution was to use beam detectors and an automated spray nozzle monitor type system like you would use around petroleum tanks or ships. (I think I was in there 15-20 years ago).
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Brett
10/12/2022 06:54:18 am
As an AHJ, I will say, this AHJ doesn't know what they're talking about. Early detection and evacuation I can fully support. Fire suppression, no. Ask him to provide code references and actual example projects where fire suppression was provided in a similar structure.
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Bill
10/12/2022 08:46:10 am
2018 IBC Section 3102.4 Allowable floor areas. The area of a membrane structure shall not exceed the limitations specified in Section 506.
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Brett
10/12/2022 09:11:23 am
Bill, I apologize if my comment was harsh. However, in my 20+ years in this field, there are many people (AHJs, Architects, and Engineers) who require things from a position of misunderstanding or ignorance. A more measured response from an AHJ facing such resistance should be to reassess their position. Additionally, I was quick to respond and was merely considering an air supported membrane structure or tent. I did not consider a structure which has membrane portions as sometimes used as architectural elements. In those instances, fire suppression systems are commonly used throughout the structure. However, I've never seen an air supported structure nor a tent style membrane structure with a fire suppression system throughout.
Bill
10/12/2022 09:26:12 am
Brett, although I don't disagree with the benefit of early detection, I'm not sure how you can disregard a requirement from an AHJ perspective. Chapter 11 of the 101 addresses the special structures, such as the one in question, and 11.1.8 specifically requires sprinklers based on the occupancy chapters that would apply.
Bill
10/12/2022 09:36:28 am
Sorry. It should have been 11.1.1
Tom W
10/12/2022 12:03:42 pm
We just finished one up for the Football Hall of Fame in Canton, OH. The use group was listed as an A-3 and under the Ohio Building Code, we are allowed to exclude sprinklers where "Areas used exclusively as participant sports areas where the main floor area is located at the same level as the level of exit discharge of the main entrance and exit." There were 3 auxiliary buildings within the dome itself that we had to install sprinklers in but not the actual dome. I do know they had to have low pressure alarms for the dome in the event of an air loss that would notify the fire dept, as well as smoke detectors and pull stations. The FD did want us to add a few hose valves on the outside of the auxiliary buildings in the dome, but that wasn't a big deal.
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HJ
10/13/2022 08:48:02 am
There are some relevant special provisions in NFPA 1(2018 Ed.):
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Terry
12/13/2022 08:16:58 pm
My company is currently providing fire suppression solutions for the Mercedes’ Benz and Alamo Dome Stadium. We’re currently working on a system for a soccer stadium in Hong Kong. Water cannons are being used along with sprinkler systems for the MB & AD stadiums. The stadiums are used for other activities such as Monster truck events where fuel is stored in the middle of the fields. The water cannons were added as additional fire protection for these stadiums. I’ve also been approached for a basketball facility such as you describes with seating capacity for 3,000 occupants. The structure cannot support a fire suppression system; however, water cannons can be an option when interconnected into automated fire alarm system.
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