Monolithic Dome Project
A monolithic 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.
Due to their structural integrity, they are used as the containment buildings at some nuclear power plants
Forms have been made using nearly every common structural material including air pressure supported fabric.
Monolithic domes are a form of monolithic architecture.
The igloo may be the earliest form of monolithic dome. While it is constructed of blocks of compressed snow, 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 the arch, and the insulation is due to the minimal surface area of a spherical section.
The first modern monolithic dome structure was built in Provo, Utah and opened in 1963 as an ice skating rink. Called Ream’s Turtle after its 1967 conversion into a general store by new owner Paul Ream, the building stood until it was demolished in 2006 for new construction.
Ream’s Turtle was built by first creating a mound of dirt in the desired shape of the shell, an ellipsoidal section 240 feet (73 m) long, 160 feet (49 m) wide and 40 feet (12 m) high. The mound was then covered in a grid of rebar, to provide strength, and a layer of concrete approximately 4 inches (100 mm) 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.
The dome, when finished, is earthquake, tornado, and hurricane resistant (the US Federal Emergency Management Agency rates 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 in Florida survived direct hits by Hurricane Katrina in 2005.
- Many monolithic domes were in the path of the 2005 and 2006 wildfires in Oklahoma and Texa, and survived with only slight charring of the exterior foam insulation.
- In 2003, a monolithic dome government building in Iraq survived a direct hit by a 5,000 lb (2,300 kg) bomb. The interior of the structure was totally destroyed, but the dome itself remained standing (see picture).
The demolition of Ream’s Turtle also demonstrated the durability of the monolithic dome structure. A wrecking ball demolished 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 a thermal mass inside the building, reducing interior temperature fluctuations far more than the traditional home’s insulation inside of a brick or stone veneer.