Expert: Richard Taylor, AIA - 5/28/2003

Question
Are geodesic homes catastrophy resistant due to their shape or concrete material construction?
Are there other types of homes that are earthquake resistant/proof. What makes them architecturally sound?

Answer
Debra:

Thanks for your question!

The geodesic dome structural system was invented by the self-styled inventor and architect Buckminster Fuller.  He was looking for a way to construct simple shelters, easily built by untrained labor, and that would be exceptionally structurally sound.

Fuller's domes aren't made from concrete.  Rather, they're made from short lengths of steel (and in some cases wood) rods that are connected into hexagons linked together.  There are some concrete domes structures, but they're different from the geodesic dome concept.  Geodesic domes gain their strength from the connections; concrete domes from their weight and reinforcing steel.

Dome shapes in general have some added resistance to natural disasters.  Since they are generally low, ground-hugging structures, and don't present a flat face to the wind, they tend to hold up better in hurricanes and tornadoes (and floods).  And concrete domes, because of their mass and monolithic construction, hold together better under some stresses.

Earthquake resistance is another story.  Unlike wind events that push steadily on the side of a building, earthquakes exert repeated, violent side-to-side forces on structures, separating the above-ground parts from the foundations.  One of the tricks to earthquake resistance is a good connection between the foundation and the structure.  But that's just the tip of the iceberg.  Earthquake resistance is a very complex science.

Earthquake resistant construction is less about the type of building and more about the way elements of the building are connected and how the building is connected to the earth.  The most earthquake-resistant homes are the ones that aren't built in earthquake zones!

Generally, any building made primarily of unreinforced masonry is highly suseptible to earthquake damage - they just fall apart at the joints - as we see time and time again in parts of the world where houses are made of stacked up stones and blocks.  Rigid, stiff construction fails sooner than flexible construction.

Wood frame construction holds up much better, assuming that the proper connections have been made.

Monolithic concrete construction (as in a dome) can be quite sound under earthquake stress if it is properly reinforced.  BUT - do you want tons of concrete over your head, reinforced or not, in an earthquake?

Structures that move easily when the earth moves don't suffer as much damage.  "Roll with the punches" is the motto in earthquake-resistant design.  That can be accomplished with almost any construction type - none is necessarily more earthquake-resistant than another by itself.

Hope this helps!

Richard Taylor, AIA
Richard Taylor Architects, LLC
www.rtaylorarchitects.com