Architectural domes have long been used for buildings of the utmost importance. From the Kremlin in Moscow to the US Capitol in Washington, DC, domes make an appearance on some of the most iconic government buildings around the world. Similarly, domes are often featured in buildings with religious significance, including the onion domes of St. Basil’s Cathedral in Russia, the Duomo (Florence Cathedral) in Italy, the Dome of the Rock in Jerusalem, and even the Taj Mahal in India.
While historic domes continue to be used to signify buildings of great cultural significance, modern monolithic dome structures form buildings of many types across the US and around the world. Monolithic domes are much more commonly utilized than many people think. The reason for the popularity of the monolithic dome lies behind the actual structure of the dome itself.
How Are Domes Structured?
It’s essential to understand a dome’s shape as well as the forces of nature that operate upon it to understand how one works. In simplest terms, a dome is a self-supporting curved structure shaped like part of a sphere. A dome relies on a few essential forces to support a hemispherical roof without columns or another support system rising from the floor beneath:
- Normal force—this force of nature is the support force exerted on the dome’s structure via contact with the base and the earth the building is resting on. This force presses upwards from the ground.
- Gravity—this force of nature is caused by the pull the earth has on all things toward its center and pulls the dome downward. Gravity can also be described as the weight of the materials used to construct the dome.
- Compression—this force acts on each component of a dome, pressing into it from both sides. Imagine a dome constructed of bricks; each brick receives pressure from the bricks surrounding it to hold it in place.
- Tension—this force acts outwardly from each component of a dome. In our brick dome example, imagine each brick pressing against and supporting the bricks next to it.
- Thrust—the above forces combine to press upward (normal force) and pull downward (gravity), compacting the dome and increasing the compression and tension that stabilizes the dome’s curved surface. When the forces reach this equilibrium, the line of thrust ensures its stability.
While not constructed out of individual bricks, monolithic domes utilize the same principles of force to provide an exceptionally strong dome structure. First, a ring-shaped concrete foundation is built, reinforced by steel rebar. Then, a pneumatic (air-filled) form shapes the next step—a polyurethane foam insulative layer. Finally, depending on the diameter of the circle and height of the dome, rebar is extended over the foam layer, providing a structure to guide the layer of sprayed concrete that will form the final shell of the dome’s roof.
Why Is Dome Structure Beneficial?
Humans have realized the benefits of dome structures for millennia. Smaller-scale domes have been in use since some of the first non-cave dwellings known to mankind, in the form of domed mud hut roofs, igloos, and the like. These smaller structures naturally lent themselves to dome structure due to the materials and tools available—mainly natural elements, hands, and simple shaping tools. Better yet, domes allowed increased space inside a structure without the need for internal supports.
The ancient Romans, too, realized the benefits of eliminating traditional support structures. Previously, both Greeks and Romans architects had relied on columns to support their larger stone buildings, even as the Romans began to use arches liberally in their large-scale construction. Once it became clear that a dome structure (essentially, a 360-degree arch) did not require an internal maze of columns to support it, the dome structure of the Pantheon was born.
Modern monolithic dome structures hold numerous benefits that far exceed their predecessors, including:
- Strength. Due to the principles of force listed above as well as the heavy-duty materials used to construct a monolithic dome, domes can withstand incredible force and bear heavy loads. Force applied at the apex (highest point) is distributed across the dome’s surface and down to the concrete foundation.
- Durability. Because of this strength, dome structures typically last much longer than other structures of the same size. They are wind-resistant due to their curved surface, and quite regularly weather violent storms without damage. In addition, monolithic domes are water-resistant and fire-resistant due to their construction.
- Maintenance. As compared to traditional shingled, tiled, metal, and other popular industrial and residential roofing materials, the masonry or concrete of a dome requires relatively little maintenance. Mostly, this is due to the absence of pests like termites as well as the overall durability of the materials.
- Energy efficiency. While the expansive nature of a dome structure may seem as if it would be costly to heat and cool, the opposite is true in the case of a monolithic dome. Compared to timber construction, the foam and concrete construction of a monolithic dome serves to insulate the structure perfectly. It allows the conditioned air to circulate within without escaping outside—this has the effect of lowering energy costs.
- Space. Finally, the most noted benefit of a dome structure is the sheer amount of space created within the structure without the need for supports rising from the floor beneath it. The resulting open space allows architects to design rooms within a dome structure in practically any configuration and leads to true customization of the interior.
What Types of Buildings Can Benefit From Dome Structures?
As mentioned, dome structures have existed throughout human history, from the smallest individual dwellings like igloos and mud huts to the most important governmental buildings and religious cathedrals man ever created. While somewhat different from the brick, mud, and snow domes of the past, the modern monolithic dome can enjoy a similar diversity.
Many types of buildings can reap the benefits of dome structures, including:
- School buildings: The large amount of versatile interior space and overall durability of a dome structure lends itself well to a building as long-lasting as a school building. Also, patrons and communities alike experience energy efficiency and cost-saving benefits.
- Industrial buildings: Monolithic dome structures are used the world over to store industrial materials like sand, salt, lime, and more. The durability and low-maintenance nature of dome structures protect the materials housed within with little need for upkeep.
- Commercial buildings: Businesses within many industries require large, open spaces not interrupted by internal supports. Whether the building is constructed to house a fleet of vehicles or form an interior gathering space, dome structures are enormously useful for commercial applications.
- Community building: Dome structures can benefit community buildings, churches, convention centers, and gathering spaces of all kinds by providing a large amount of interior space. These structures are also beneficial for communities in that they do not require maintenance or high energy costs to support over their long lifespans.
The First Name in Monolithic Dome Structures
South Industries has long been considered the leading innovator in monolithic dome structures. Founders Randy, Barry, and David South developed the unique monolithic dome construction method outlined above to address several problems created by traditional architecture—and to take advantage of the many benefits of dome structures. For more information about our process, the benefits a monolithic dome structure can have for your organization, or to schedule a tour of a dome project near you, please contact South Industries today.
Resources:
https://www.penn.museum/documents/education/penn-museum-china.pdf
https://concretedomestructures.weebly.com/analysis-of-domes.html