# Air-Supported Soccer Field



## tod13511 (Jun 25, 2014)

How do large air-supported structures fit into the 2009 IBC?  3102.3 is telling me to call it IIB construction.

If this is an A-3, I don't see how to get it into the unlimited area section (507.6) without sprinklers.  I assume you can't support sprinkler piping from an air-supported structure.  If it's an A-3 and can't be unlimited area, Table 503 and 506.2 give me 16,625 sf with a fully open perimeter.  That's not even close to soccer field size.

If this is a practice facility with no bleachers, can it be an A-4?  Section 303 states an A-4 is indoor sports with spectator seating.  If they add seating, it looks like I can call it an A-4 and apply 507.3, exception 2 for unlimited area.  This would allow them to not sprinkler the field(s).  The question is then where do I require sprinklers in this building?  In any storage rooms?  Over the single bleacher?

If there's a better answer in the IBC than the place I've arrived at, please let me know.  Thanks.

 I really just want to get over the area hump right now, and don't want to deal with questions of possible future occupancies like concerts and graduations.


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## cda (Jun 25, 2014)

You just might want to require a technical report from a fire protection engineer, at the owners cost

Yes and i think you can sprinkle them, if needed.

I take it this thing is going to be there till it blows down?


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## cda (Jun 25, 2014)

not an engineer, but saw the circus last night under the big tent,,

looks like you are headed in correct direction, seems they have to stick to the limits of the code!??????????

http://publicecodes.cyberregs.com/icod/ibc/2009f2cc/icod_ibc_2009f2cc_31_sec002.htm

This section includes provisions for construction types, height and area limitations and structural support. Otherwise, the other applicable sections of the code apply. So that a membrane structure will continue to provide its intended function, it must undergo continuous maintenance. Fire safety of such structures and the premises is regulated by the International Fire Code® (IFC®).

Because of the limited fire-resistance capabilities of the membrane, membrane structures are usually classified as Type IIB, IV or V. These are defined as follows:

Type IIB-Membrane structures in which the membrane is noncombustible as defined by Section 703.4; or membrane-covered structures in which the frame or cable is noncombustible and the membrane is either noncombustible or flame resistant.

Type IV-Membrane-covered structures in which the frame is made from heavy timber and the membrane is noncombustible or flame resistant.

Type V-Membrane structures in which the membrane is flame resistant and combustible; or membrane- covered structures in which the frame or cable is combustible and the membrane is noncombustible or flame resistant.

In accordance with Section 602.2, a membrane- covered structure is to be considered as Type I or II construction, provided that the frame or cable complies with the provisions for Type I or II construction and the membrane structure is noncombustible, used exclusively as a roof and located more than 20 feet (6096 mm) above any floor, balcony or gallery floor level. This is similar to the provisions in Table 601 that do not require fire-resistance-rated roof construction under similar conditions.

The exception indicates that in recent years it has been common practice to build greenhouses with higher ridge lines. Since this increase in height, there has been no record of related property loss.

3102.4 Allowable floor areas. The area of a membrane structure shall not exceed the limitations set forth in Table 503, except as provided in Section 506.

The allowable area per floor of a membrane structure is determined using Sections 503 and 506, based on the construction types established in Section 3102.3.

3102.5 Maximum height. Membrane structures shall not exceed one story nor shall such structures exceed the height limitations in feet set forth in Table 503.

Exception: Noncombustible membrane structures serving as roofs only.

Membrane structures are most commonly used to enclose large, open areas without intermediate structural supports, such as columns. For this reason, as well as the engineering difficulties associated with multistory buildings, membrane structures are limited to one story and the maximum height permitted in Table 503. The specific reference to Table 503 intends that any height increases allowed by Section 504 would not be permitted. The height is not limited, however, if a noncombustible membrane is used as a roof membrane only.


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## steveray (Jun 25, 2014)

A-4...See exception 2.....If it is only fields.....if they want to put bathrooms or anything else in it....NG...Sprinkler those areas...

507.2 Sprinklered, one story.

The area of a one-story, Group B, F, M or S building or a one-story Group A-4 building of other than Type V construction shall not be limited when the building is provided with an automatic sprinkler system throughout in accordance with Section 903.3.1.1, and is surrounded and adjoined by public ways or yards not less than 60 feet (18 288 mm) in width.

Exceptions:

1. Buildings and structures of Type I and II construction for rack storage facilities which do not have access by the public shall not be limited in height provided that such buildings conform to the requirements of Section 507.1 and NFPA 231C.

2. The automatic sprinkler system shall not be required in areas occupied for indoor participant sports, such as tennis, skating, swimming and equestrian activities, in occupancies in Group A-4, provided that:

2.1. Exit doors directly to the outside are provided for occupants of the participant sports areas, and

2.2. The building is equipped with a fire alarm system with manual fire alarm boxes installed in accordance with Section 907.


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## steveray (Jun 25, 2014)

All that being said.....I have always struggled with bringing in spectators allows you to be "less safe".....?.....I did a bubble once.....If you have any questions or just want to kick stuff around, PM me and I will give you my # and email...


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## tod13511 (Jun 25, 2014)

Thanks Steve.  Can it be an A-4 without spectator seating (none is planned)?  Would you sprinkler the seating areas?


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## fatboy (Jun 25, 2014)

It is probably a non-issue, but I have often wondered what the leak down rate is on those type of structures. If there is a power outage, how long do the folks have to get out of there?


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## north star (Jun 25, 2014)

*= + = + =*

FWIW,  ...here's what Wiki says about Air Supported Structures.



*https://en.wikipedia.org/wiki/Air-supported_structure*



Also, ***fatboy***  has raised a very good point..., what happens

to the various occupants when pressurization is lost ?

*= + = + =*


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## cda (Jun 25, 2014)

How about the tornados???


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## cda (Jun 25, 2014)

north star said:
			
		

> *= + = + =*FWIW,  ...here's what Wiki says about Air Supported Structures.
> 
> 
> 
> ...


59 seconds





Guess it depends on const make up


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## steveray (Jun 25, 2014)

FB.....it's all there already...................Support provisions usually get missesd here....

3102.8 Inflation systems.

Air-supported and air-inflated structures shall be provided with primary and auxiliary inflation systems to meet the minimum requirements of Sections 3102.8.1 through 3102.8.3.

3102.8.1 Equipment requirements.

This inflation system shall consist of one or more blowers and shall include provisions for automatic control to maintain the required inflation pressures. The system shall be so designed as to prevent over-pressurization of the system.

3102.8.1.1 Auxiliary inflation system.

In addition to the primary inflation system, in buildings exceeding 1,500 square feet (140 m2) in area, an auxiliary inflation system shall be provided with sufficient capacity to maintain the inflation of the structure in case of primary system failure. The auxiliary inflation system shall operate automatically when there is a loss of internal pressure and when the primary blower system becomes inoperative.

3102.8.1.2 Blower equipment.

Blower equipment shall meet the following requirements:

1. Blowers shall be powered by continuous-rated motors at the maximum power required for any flow condition as required by the structural design.

2. Blowers shall be provided with inlet screens, belt guards and other protective devices as required by the building official to provide protection from injury.

3. Blowers shall be housed within a weather-protecting structure.

4. Blowers shall be equipped with backdraft check dampers to minimize air loss when inoperative.

5. Blower inlets shall be located to provide protection from air contamination. The location of inlets shall be approved.

3102.8.2 Standby power.

Wherever an auxiliary inflation system is required, an approved standby power-generating system shall be provided. The system shall be equipped with a suitable means for automatically starting the generator set upon failure of the normal electrical service and for automatic transfer and operation of all of the required electrical functions at full power within 60 seconds of such service failure. Standby power shall be capable of operating independently for a minimum of 4 hours.

3102.8.3 Support provisions.

A system capable of supporting the membrane in the event of deflation shall be provided for in air-supported and air-inflated structures having an occupant load of more than 50 or where covering a swimming pool regardless of occupant load. The support system shall be capable of maintaining membrane structures used as a roof for Type I construction not less than 20 feet (6096 mm) above floor or seating areas. The support system shall be capable of maintaining other membranes at least 7 feet (2134 mm) above the floor, seating area or surface of the water.


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## Frank (Jun 26, 2014)

cda said:
			
		

> 59 seconds


Try 48 minutes per the article, the 59 second utube was time lapse photography


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## RLGA (Jun 26, 2014)

I had go through this five years ago with Arizona State University when they wanted to enclose their football practice field within an air-supported structure.  The State Fire Marshal would not approve it unless we showed some equivalencies.  At the time it was based on the 2003 IBC.  I prepared a 21-page report that analyzed each requirement applicable to the project and stated whether or not the project complied, and if it did not, what the equivalency to offset it would be.

Some of the things that were provided included: 1) no spectators allowed, thus a Group A-3 instead of a Group A-4; 2) restrict the occupant load inside; 3) provide automatic voice notification at loss of internal pressure; 4) develop a severe weather notfication system; and 5) place fire extinguishers at 75-foot intervals around perimeter.

It was eventually approved.  I would use a similar approach.


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## cda (Jun 26, 2014)

Frank said:
			
		

> Try 48 minutes per the article, the 59 second utube was time lapse photography


59 seconds sounds better


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