In the recent years, there have been an increasing number of structures using domes as one of the most efficient shapes in the world to cover large spans. Dome structures are lightweight and elegant structures that provide economical solutions for covering large areas with their splendid aesthetic appearance. Dome covers the maximum volume with the minimum material volumes with no interrupting columns in the middle with efficient shapes. Domes are used to cover large areas such as exhibition centres, sports stadia, concert halls, assembly halls, swimming pools, shopping centres and industrial buildings.
Geodesic dome is a space type of structure that looks like a section of a ball or sphere. This structure is made of a grid of triangles that eventually form a spherical surface. The greater the number of triangles the better form of a sphere shaped dome is approached. This type of domes became a reality due to efforts of R. Buckminister Fuller, an American Engineer. The surface area of a geodesic dome constitutes only 38% of the surface area of a box-shaped building that encloses the same floor area. Geodesic domes are very strong and they resist all types of loading very efficiently ex: earthquake loads, wind loads etc.
The Engineering Behind Geodesic Domes
A geodesic dome is a spherical building in which the supporting structure is a lattice of interconnecting tetrahedrons (a pyramid with three sides and a base) and octahedrons (an eight sided figure—two pyramids with four sides and a base, placed base to base). Since the pyramid shape is made from triangles, the supporting structure is multiple triangular frames. So, in other words, the struts of a geodesic dome are joined together in triangles, with the points of the triangles creating the sphere’s “surface.” The edges of the triangles form geodesics over the dome’s surface. The word geodesic refers to the shortest distance between two points on a curved surface, and it is a Greek word that means “earth dividing.”
Several physical and mathematical ideas factor into building a geodesic dome. For example, a convexly curved surface is stronger than a flat one, most materials are stronger in tension than in compression, and the most rigid structure is a triangle. A hemisphere encloses the most space with the least amount of material while the tetrahedron encloses the least volume with the most surface. These principles make geodesic domes the strongest, lightest, most energy efficient buildings ever devised. Structural patterns of geodesic domes vary in complexity. Some domes have been built using simple interconnecting triangles as a support structure while others have icosahedrons as their supporting structure. An icosahedron is the geometric form having the greatest number of identical and symmetrical faces—it has 20 faces, 12 vertices, and 30 edges. The more complex the structure is, the stronger it is.
Geodesic spheres and domes come in various frequencies. The frequency of a dome relates to the number of smaller triangles into which it is subdivided. A high frequency dome has more triangular components and is more smoothly curved and sphere-like.
Geodesic Dome Features
The idea is by relying on the strength of the triangles, these structures can be constructed of more affordable and sustainable materials, such as aluminum, instead of steel and concrete. Because the framework creates a self-reinforcing roof and siding system, the necessity for any inner supports or “load-bearing” columns is eliminated. Besides, up to half of the triangles in a geodesic dome’s lowest row can be removed with no harm to the structure’s strength. This allows a designer to open doors and windows when planning a geodesic dome building. Skylights can be installed on any surface within the basic triangular frame. Dormers, copulas, and flat-roofed wings can also be built.
Because the geodesic dome resembles a sphere, it has a relatively low surface-area-to-volume ratio, which means that its volume is larger than its surface area. So it can enclose a massive amount of volume when compared with the size of the structure itself. As the area of exposure of the geodesic dome is very less compared to outside environment, the building has better thermal comfort than a rectilinear structure.
A quality geodesic dome structure is airtight and structurally reliable. These are the factors that lower energy costs, a primary concern when building a geodesic dome home. Because the frame is basically airtight, condensation can be a problem. Usually, it is managed by the heating and cooling system, but moisture can build up when the dome stays closed up for a few days. This can be easily solved by leaving a door or window open.