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Example of a Monolithic dome at the Centro de la Familia de UtahCenter,Genola, Utah.
Amonolithic dome(from Greek mono- and -lithic, meaning one stone) is a structure cast in a one-piece form. The form may be permanent or temporary and may or may not remain part of the finished structure. Monolithicdomesare a form ofmonolithic architecture.
Theigloomay be the earliest form of monolithic dome. While it is constructed of blocks of compressedsnow, these blocks melt and re-freeze to form a strong, homogeneous structure. The dome-like shape of the igloo exhibits the two major advantages of a dome-shaped structure: great strength, and good insulation. The strength is due to the natural strength of thearch, and the insulation is due to the minimal surface area of asphericalsection.
The first modern monolithic dome structure was built inProvo, Utahand opened in 1963 as anice skatingrink. CalledTurtle Reamsafter its 1967 conversion into ageneral storeby new owner Paul Ream, the building stood until it was demolished in 2006 for new construction.
Turtle Reams was built by first creating a mound of dirt in the desired shape of the shell, anellipsoidalsection 240 feet (73m) long, 160 feet (49m) wide and 40 feet (12m) high. The mound was then covered in a grid ofrebar, to provide strength, and a layer of concrete approximately 4 inches (100mm) thick. After the concrete was cured, the dirt was excavated through the doorways, leaving the roof standing in its place. The floor was then poured to finish the structure.
Today, monolithic domes are used in a variety of residential, commercial and industrial projects. Because of the strength, durability and economics, they are used to store large amounts of various commodities in the cement, fertilizer, agricultural, power and mining industries. Due to their structural integrity, they are used as thecontainment buildingsat somenuclear power plants. Forms have been made using nearly every common structural material including air pressure supported fabric.
Modern construction differs significantly from the original concrete-over-dirt method. The current methods were developed by three brothers from Idaho: David, Barry, and Randy South. The first dome built using these method was constructed in April 1976 inShelley, Idaho:
A reinforced concrete foundation, or ring beam, is constructed, defining the shape of the base of the structure.
, is attached to the foundation and inflated with an air blower. The air form contains anairlockto allow workers to enter the form while it is inflated.
A layer ofpolyurethanefoam is sprayed on the interior of the form. (Its purposes are to give rigidity to the air form, secure the re-bar in place, provide support for spraying in the concrete mixture, and insulate the final structure.)
Rebar is attached to the outside layer of foam, using clips that are attached to the foam.
Several inches of concrete are sprayed over the re-bar frame.
After the concrete has set, the blower is turned off.
The exposed surface of the air form may be left as is, or a surface treatment such as paint, tile, etc., may be applied. (Proper selection of air form material will ensure prevention from long-term degradation due toultraviolet radiation.)
In instances where necessity requires economical construction for multiple small and basic dwellings, the dome can be built without insulation and the air form can be removed after completion and re-used to build additional domes.
This domed government building inBaghdad, formerly a part ofSaddam Husseins regime, was hit by a 5,000lb (2,300kg). bomb.
Apart from the hole made by the entry of the bomb, it remained structurally sound.
The dome, when finished, isearthquaketornadoandhurricaneresistant (the USFederal Emergency Management Agencyrates them as near-absolute protection from F5 tornadoes and Category 5 Hurricanes). Recently, a number of monolithic domes constructed using MDI techniques have survived major disasters:
Several monolithic domes inFloridasurvived direct hits byHurricane Katrinain 2005.
Many monolithic domes were in the path of the 2005 and 2006wildfiresinOklahomaandTexas, and survived with only slight charring of the exterior foam insulation.
In 2003, a monolithic dome government building inIraqsurvived a direct hit by a 5,000lb (2,300kg).bomb. The interior of the structure was totally destroyed, but the dome itself remained standing (see picture).
The demolition of Reams Turtle also demonstrated the durability of the monolithic dome structure. Awrecking balldemolished a strip several feet wide around the perimeter of the structure, without a collapse. When a doorway on one side was pulled down, the dome finally tipped over, and collapsed.
The monolithic dome, for a number of reasons, is very energy efficient. The spherical sections of the dome offer minimal surface area for the volume they contain, so there is less surface for heat transfer with the outside air. The one piece construction of the monolithic dome also eliminates many of the seams through which air can leak, though this is mitigated to some degree in residential domes by the addition of multiple doors and windows. By placing the insulating foam on the outside of the concrete shell, the concrete acts as aThermal massinside the building, reducing interior temperature fluctuations far more than the traditional homes insulation inside of a brick or stone veneer.
While the monolithic dome has numerous demonstrated engineering advantages, there are also some disadvantages, both engineering and social.
The techniques used in monolithic dome construction are very different from normal construction methods, so only specially trained construction crews are suited for building a dome using the modern techniques.
The curved surfaces inherent to monolithic dome construction often result in oddly shaped rooms when divided up, which can result in wasted space in narrow corners. There are issues of wasted floor space due to wall curvature and problems fitting furniture, similar to those ofQuonset huts. This effect can be minimized by constructing the dome on a stem wall, or by using an airform of such shape as to allow for straight, vertical walls at ground level.
The monolithic domes lack of seams may make it too well sealed;dehumidifiersare required in all but the driest climates.
Social disadvantages of monolithic domes are to a large degree shared bygeodesic domes, due to the similar shape and unorthodox construction. These disadvantages are:
The radically different appearance of the domes also decreases the appeal for their use as private residencesthe standard circular base doesnt fit well on small lots found in many areas, and the strange appearance and design may run afoul of neighborhood building covenants. Depending on the situation, a large variety of variations available from the standard circular shape can avoid some of these problems.
Building permits may be difficult to obtain if local officials are not familiar with the monolithic dome.
Resale of a monolithic dome home may be difficult because of its unconventional appearance.
The largest monolithic dome in the world is the home ofFaith Chapel Christian CenterinBirmingham, AL, which is 72 feet (22m) tall, and 280 feet (85m) in diameter.Inside is a floor area of 74,500 square feet (6,920m2) in two levels.
Some communities in the United States have chosen to use monolithic dome technology in the construction of new schools.A mapof recently built monolithic dome schools can be found here:
A residential house, the monolithicDome of a HomeinPensacola Beach, Florida, has experienced several hurricanes since it was built.
Monolithic Dome of a Home inPensacola Beach, Florida, afterHurricane Dennisin 2005
Bubble Houses (Litchfield Park, Arizona)
FCCC Monolithic Dome Facts. Archived fromthe originalon 2008-02-29
Architectural Dome Facts. Archived fromthe originalon 2008-06-19
Wikimedia Commons has media related to
Building Monolithic Domes, by Sean Lanham, Architecture Week
Trinity Dome Construction Log, a first-time homebuilders experience
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This page was last edited on 19 February 2018, at 06:28.