Air-supported structure
Encyclopedia
Building envelope
The building envelope is the physical separator between the interior and the exterior environments of a building. Another emerging term is "Building Enclosure". It serves as the outer shell to help maintain the indoor environment and facilitate its climate control...
, so that air is the main support of the structure, and where access is via airlocks.
The concept was popularized on a large scale by David H. Geiger
David H. Geiger
David H. Geiger was an engineer who invented the air-supported fabric roof system that was used at about half the domed stadiums in the U.S...
with the United States pavilion at Expo '70
Expo '70
was a World's Fair held in Suita, Osaka, Japan between March 15 and September 13, 1970. The theme of the Expo was "Progress and Harmony for Mankind." In Japanese Expo '70 is often referred to as Ōsaka Banpaku...
in Osaka, Japan in 1970.
It is usually dome-shaped
Dome
A dome is a structural element of architecture that resembles the hollow upper half of a sphere. Dome structures made of various materials have a long architectural lineage extending into prehistory....
, since this shape creates the greatest volume
Volume
Volume is the quantity of three-dimensional space enclosed by some closed boundary, for example, the space that a substance or shape occupies or contains....
for the least amount of material. To maintain structural integrity, the structure must be pressurized such that the internal pressure
Pressure
Pressure is the force per unit area applied in a direction perpendicular to the surface of an object. Gauge pressure is the pressure relative to the local atmospheric or ambient pressure.- Definition :...
equals or exceeds any external pressure being applied to the structure (i.e. wind
Wind
Wind is the flow of gases on a large scale. On Earth, wind consists of the bulk movement of air. In outer space, solar wind is the movement of gases or charged particles from the sun through space, while planetary wind is the outgassing of light chemical elements from a planet's atmosphere into space...
pressure). The structure does not have to be airtight to retain structural integrity—as long as the pressurization system that supplies internal pressure replaces any air leakage, the structure will remain stable. All access to the structure interior must be equipped with two sets of doors or revolving door (airlock
Airlock
An airlock is a device which permits the passage of people and objects between a pressure vessel and its surroundings while minimizing the change of pressure in the vessel and loss of air from it...
). Air-supported structures are secured by heavy weights on the ground, ground anchors, attached to a foundation, or a combination of these.
Among its many uses are: sports and recreation facilities, warehousing, temporary shelters, and radome
Radome
A radome is a structural, weatherproof enclosure that protects a microwave or radar antenna. The radome is constructed of material that minimally attenuates the electromagnetic signal transmitted or received by the antenna. In other words, the radome is transparent to radar or radio waves...
s. The structure can be either wholly, partial, or roof-only air supported. A fully air-supported structure can be intended to be a temporary or semi-temporary facility or permanent, whereas a structure with only an air-supported roof can be built as a permanent building.
The biggest air-supported dome in North America
North America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...
is the dome at the École secondaire publique Louis-Riel
École secondaire publique Louis-Riel
École secondaire publique Louis-Riel is a high school in the Blackburn Hamlet neighbourhood of Ottawa, Ontario, Canada, part of the Conseil des écoles publiques de l'Est de l'Ontario...
(Louis-Riel Secondary Public School) in Ottawa
Ottawa
Ottawa is the capital of Canada, the second largest city in the Province of Ontario, and the fourth largest city in the country. The city is located on the south bank of the Ottawa River in the eastern portion of Southern Ontario...
, Ontario
Ontario
Ontario is a province of Canada, located in east-central Canada. It is Canada's most populous province and second largest in total area. It is home to the nation's most populous city, Toronto, and the nation's capital, Ottawa....
. It is the second biggest air-supported dome in the world.
Shape
The shape of an air-supported structure is limited by the need to have the whole envelope surface evenly pressurized. If this is not the case, the structure will be unevenly supported, creating wrinkles and stress points in the pliable envelope which in turn may cause it to fail.In practice, any inflated surface involves a double curvature. Therefore the most common shapes for air-supported structures are hemispheres, ovals, and half cylinders.
Structure
The main loads acting on the air-supported envelope are the internal air pressure, wind, and snow loads. In order to cope with the varying loads of wind and snow, the inflation of the structure must be adjusted accordingly. Modern structures have computer controlled mechanical systems that can sense the dynamic loads and compensate the inflation for it. The highest quality ones are able to withstand winds up to 120 mph (190 km/h), and snowloads up to 40 pounds per square yard.
Danger of sudden collapse is nearly negligible, since the structure will deform or sag in case a heavy load (snow or wind) is exerted on it. Only if these warning signs are ignored or not noticed, then the build-up of an extreme load may rupture the envelope, leading to a sudden deflation and collapse.
Material
The materials used for air-supported structures are similar to those used in tensile structureTensile structure
A tensile structure is a construction of elements carrying only tension and no compression or bending. The term tensile should not be confused with tensegrity, which is a structural form with both tension and compression elements....
s, namely synthetic fabrics such as fibreglass and polyester
Polyester
Polyester is a category of polymers which contain the ester functional group in their main chain. Although there are many polyesters, the term "polyester" as a specific material most commonly refers to polyethylene terephthalate...
. In order to prevent deterioration from moisture and ultraviolet
Ultraviolet
Ultraviolet light is electromagnetic radiation with a wavelength shorter than that of visible light, but longer than X-rays, in the range 10 nm to 400 nm, and energies from 3 eV to 124 eV...
radiation, these materials are coated with polymers such as PVC
Polyvinyl chloride
Polyvinyl chloride, commonly abbreviated PVC, is a thermoplastic polymer. It is a vinyl polymer constructed of repeating vinyl groups having one hydrogen replaced by chloride. Polyvinyl chloride is the third most widely produced plastic, after polyethylene and polypropylene. PVC is widely used in...
and Teflon.
Depending on use and location, the structure may have inner linings made of lighter materials for insulation or acoustics.
Air pressure
The interior air pressure required for air-supported structures is not as much as most people expect and certainly not discernible when inside. The amount of pressure required is a function of the weight of the material - and the building systems suspended on it (lighting, ventilation, etc.) - and wind pressure. Yet it only amounts to a small fraction of atmospheric pressureAtmospheric pressure
Atmospheric pressure is the force per unit area exerted into a surface by the weight of air above that surface in the atmosphere of Earth . In most circumstances atmospheric pressure is closely approximated by the hydrostatic pressure caused by the weight of air above the measurement point...
. Internal pressure is commonly measured in inches of water
Inch of water
Inches of water, wc, inch water column , inAq, Aq, or inH2O is a non-SI unit for pressure. The units are by convention and due to the historical measurement of certain pressure differentials. It is used for measuring small pressure differences across an orifice, or in a pipeline or shaft...
, inAq, and varies fractionally from 0.3 inAq for minimal inflation to 3 inAq for maximum, with 1 inAq being a standard pressurization level for normal operating conditions. In terms of the more common pounds per square inch
Pounds per square inch
The pound per square inch or, more accurately, pound-force per square inch is a unit of pressure or of stress based on avoirdupois units...
, 1 inAq equates to a mere 0.037 psi (2.54 mBar, 254 Pa).
Advantages and disadvantages
There are some advantages and disadvantages as compared to conventional buildings of similar size and application.Advantages:
- Considerably lower initial cost than conventional buildings
- Lower operating costs due to simplicity of design (wholly air-supported structures only)
- Easy and quick to set up, dismantle, and relocate (wholly air-supported structures only)
- Unobstructed open interior space, since there is no need for columns
- Able to cover almost any project
- Custom fabric colors and sizes, including translucent fabric, allowing natural sunlight in
Disadvantages:
- Continuous operation of fans to maintain pressure, often requiring redundancy or emergency power supply.
- Dome collapses when pressure lost or fabric compromised
- Cannot reach the insulation values of hard-walled structures, increasing heating/cooling costs
- Limited load-carrying capacity
- Conventional buildings have longer lifespan
In operation
- Pontiac SilverdomePontiac SilverdomeThe Silverdome is a domed stadium located in the city of Pontiac, Michigan, USA, which sits on . It was the largest stadium in the National Football League until FedEx Field in suburban Washington, D.C...
, Pontiac, MichiganPontiac, MichiganPontiac is a city in the U.S. state of Michigan named after the Ottawa Chief Pontiac, located within the Detroit metropolitan area. As of the 2010 census, the city had a total population of 59,515. It is the county seat of Oakland County...
, United StatesUnited StatesThe United States of America is a federal constitutional republic comprising fifty states and a federal district... - St. Louis Science CenterSt. Louis Science CenterThe Saint Louis Science Center is a collection of buildings including a science museum and planetarium in St. Louis, Missouri, on the southeastern corner of Forest Park. The Planetarium opened in 1963, and it was expanded and renamed as the Saint Louis Science Center in 1983...
Exploradome, Saint Louis, Missouri, United StatesUnited StatesThe United States of America is a federal constitutional republic comprising fifty states and a federal district... - Carrier DomeCarrier DomeThe Carrier Dome is a 49,250-seat domed sports stadium located on the campus of Syracuse University in the University Hill neighborhood of Syracuse, New York, USA. It is home to the Syracuse Orange football, basketball, and lacrosse teams. High school football championships are also held in "The...
, Syracuse, New YorkSyracuse, New YorkSyracuse is a city in and the county seat of Onondaga County, New York, United States, the largest U.S. city with the name "Syracuse", and the fifth most populous city in the state. At the 2010 census, the city population was 145,170, and its metropolitan area had a population of 742,603...
, United States - Hubert H. Humphrey MetrodomeHubert H. Humphrey MetrodomeThe Hubert H. Humphrey Metrodome, commonly called the Metrodome, is a domed sports stadium in downtown Minneapolis, Minnesota, United States. Opened in 1982, it replaced Metropolitan Stadium, which was on the current site of the Mall of America in Bloomington and Memorial Stadium on the University...
, Minneapolis, MinnesotaMinneapolis, MinnesotaMinneapolis , nicknamed "City of Lakes" and the "Mill City," is the county seat of Hennepin County, the largest city in the U.S. state of Minnesota, and the 48th largest in the United States...
, United States - Tokyo DomeTokyo DomeTokyo Dome is a 55,000-seat baseball stadium located in Bunkyo Ward of Tokyo, Japan.The stadium opened for business on March 17, 1988. It was built on the site of the Velodrome which was next door to the site of the predecessor ballpark, Kōrakuen Stadium...
, TokyoTokyo, ; officially , is one of the 47 prefectures of Japan. Tokyo is the capital of Japan, the center of the Greater Tokyo Area, and the largest metropolitan area of Japan. It is the seat of the Japanese government and the Imperial Palace, and the home of the Japanese Imperial Family...
, JapanJapanJapan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south... - Burswood Dome, Perth, Western AustraliaPerth, Western AustraliaPerth is the capital and largest city of the Australian state of Western Australia and the fourth most populous city in Australia. The Perth metropolitan area has an estimated population of almost 1,700,000....
- Generations Sports Complex Dome, Muncy, PennsylvaniaMuncy, PennsylvaniaFor other places named 'Muncy', please see Muncy .Muncy is a borough in Lycoming County, Pennsylvania, in the United States. The name Muncy comes from the Munsee Indians who once lived in the area. The population was 2,663 at the 2000 census. It is part of the Williamsport, Pennsylvania...
, United States - Bennett Indoor Complex, Toms River, New JerseyToms River, New JerseyToms River is a census-designated place and unincorporated area located within Toms River Township and is the county seat of Ocean County, New Jersey. It is part of a larger Toms River Township...
, United States - Dalplex (athletics complex), Halifax, Nova ScotiaNova ScotiaNova Scotia is one of Canada's three Maritime provinces and is the most populous province in Atlantic Canada. The name of the province is Latin for "New Scotland," but "Nova Scotia" is the recognized, English-language name of the province. The provincial capital is Halifax. Nova Scotia is the...
, CanadaCanadaCanada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean... - Rocky Lake Dome Arena, Bedford, Nova ScotiaBedford, Nova ScotiaBedford is a community in the Halifax Regional Municipality, Nova Scotia, Canada. It was an independent town from 1980-1996. Bedford lies on the northwestern end of Bedford Basin, an extension of the Halifax Harbour...
, Canada. - Harry Jerome Sports Center, Burnaby, British ColumbiaBurnaby, British ColumbiaBurnaby is a city in British Columbia, Canada, located immediately to the east of Vancouver. It is the third-largest city in British Columbia by population, surpassed only by nearby Surrey and Vancouver....
, Canada. - The Alaska Dome, Anchorage, AK
- Krenzler FieldKrenzler FieldKrenzler Field is a soccer stadium in Cleveland, Ohio on the campus of Cleveland State University. It serves as the home field to the men's and women's varsity teams and formerly the Cleveland City Stars of the USL First Division...
, Cleveland State UniversityCleveland State UniversityCleveland State University is a public university located in downtown Cleveland, Ohio. It was established in 1964 when the state of Ohio assumed control of Fenn College, and it absorbed the Cleveland-Marshall College of Law in 1969...
, Cleveland, OH, United States
Former notable domes
- BC Place StadiumBC Place StadiumBC Place is a multi-purpose stadium located at the north side of False Creek, in Vancouver, British Columbia, Canada. It serves as the home field for the BC Lions of the Canadian Football League and the Vancouver Whitecaps FC of Major League Soccer . Originally opened on June 19, 1983 as the...
, VancouverVancouverVancouver is a coastal seaport city on the mainland of British Columbia, Canada. It is the hub of Greater Vancouver, which, with over 2.3 million residents, is the third most populous metropolitan area in the country,...
, British ColumbiaBritish ColumbiaBritish Columbia is the westernmost of Canada's provinces and is known for its natural beauty, as reflected in its Latin motto, Splendor sine occasu . Its name was chosen by Queen Victoria in 1858...
, CanadaCanadaCanada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...
. (Largest air-supported stadium in the world. The roof was changed to a retractable roof in 2011.) - RCA DomeRCA DomeRCA Dome was a domed stadium, located in Indianapolis, Indiana, and the home of the Indianapolis Colts NFL franchise for 24 seasons ....
, Indianapolis, IndianaIndianapolis, IndianaIndianapolis is the capital of the U.S. state of Indiana, and the county seat of Marion County, Indiana. As of the 2010 United States Census, the city's population is 839,489. It is by far Indiana's largest city and, as of the 2010 U.S...
, United StatesUnited StatesThe United States of America is a federal constitutional republic comprising fifty states and a federal district...
. (Demolished in December 2008) - UNI-DomeUNI-DomeUNI-Dome is a multi-purpose stadium, on the campus of the University of Northern Iowa, in Cedar Falls, Iowa, United States. It opened in 1976, as the home of the UNI Panthers basketball and football teams. The facility's capacity, for football, is 16,324...
, Cedar Falls, IowaCedar Falls, IowaCedar Falls is a city in Black Hawk County, Iowa, United States, and it is home to one of Iowa's three public universities, the University of Northern Iowa. The population was 39,260 in the 2010 census, an increase from the 36,145 population in the 2000 census...
, United StatesUnited StatesThe United States of America is a federal constitutional republic comprising fifty states and a federal district...
. (Air-supported Teflon/Fiberglass roof was replaced with a steel frame-supported stainless steel/fiberglass roof in 1998.)
External links
- NRC Canadian Building Digest CBD-137 - 1971 Online version
- Tension Structures
- DESIGN MANUAL FOR GROUND-MOUNTED AIR-SUPPORTED STRUCTURES
- GUIDE FOR ESTIMATING MAXIMUM ANCHOR LCADS ON AIR-SUPPORTED STRUCTURES