With only concrete and masonry, humans have built solid inspirational roofs for thousands of years. Their strength is that they have lasted. With activity of lunar construction being challenged by the need for workers to be protected from radiation and wearing suits that support their life outside, examples from our cultural past can be reinterpreted and provide the models for our lunar habitats. The Earth’s modern warehouses and sports facilities have amazingly large enclosed spaces, but their structural strength is only to resist gravity and does not also have to contain a pressurized atmosphere that cannot leak. Their impermanence is demonstrated by howoften they are torn down and rebuilt.
The architectural term for enclosing large interior spaces, with columns, is ‘hypostyle’ and it dates back to the time of ancient Greeks. Random House dictionary (unabridged, 2011) states that the term hypóstȳlos means “under columns,” where ὑπό hypó means below or underneath and στῦλος stŷlos means column. The ancient hypostyle halls were built by designing a three dimensional structural “cell” and then replicating that over to get the size of the interior space they thought to be adequate for their needs. With time the architects pursued to push the limits of their technologies by extending the distances between the columns to their limits and raising the heights of the ceilings as part of their creative craft. This practice continued until the modern production of steel in the late 1800s. Below are just a few examples of the many that inspired Seleneca’s designers.
Great Hypostyle Hall at Karnak
Although the roof has been lost, the massive columns show that the architect of the Temple at Karnak’s ambition was to show off the grandest of interior spaces the Egyptian World had ever seen. The space was 5,000 square meters in area, supported by 134 of these massive columns in 16 rows. It is believed to date from the New Kingdom, 16th and 11th Centuries BC.
Córdoba, Spain’s Mosque/Cathedral
This is a beautiful example of art integrated into structural elements. This building was constructed as a Mosque, and later became a Catholic Cathedral.
Santa Maria Maggiore at Guardiagrele
The church of Santa Maria Maggiore at Guardiagrele in the Abruzzo region of southern Italy used groin vaults for the roofs of the corridors at its courtyard. A groin vault is made from the intersection of two barrel vaults. That means that the opening on all four sides of each bay can be exactly the same. This is good for making modular forms that can be repetitively used and interconnected. The structural magic of this form is that the heavy loads of the roof are transferred down the columns in the four corners of each bay, without the need for buttresses. In the example here we have “Gothic arches” common in Medieval times. The Romans used rounded arches. If a flattened arch is uses, a horizontal tie beam is required at the base of each arch to fight the outward thrust.
