# Eco Sphere – A Dodecahedron Tensegrity Structure

Side Cross Section View of Eco Sphere
Attach:EcoSphere/EcoSphere/Tensegrity2.jpg Δ Buckminster Fuller asked: "What's the minimal structure that can support a weight and oppose horizontal forces, that uses compression and tension, but experiences no torque?" His answer to (his own) question was: The Dodecahedron!

The Dodecahedron has 12 sides, and for each side, there is an opposite face, parallel to the first. However, if we look at a "wire mesh" version of the dodecahedron and we have an edge rather than a face pointing directly at us, then another symmetry becomes apparent. Now two faces are facing us equally (though not squarely), and we see straight through, with no obstructions at all, looking through a second pair of similarly aligned faces.

We could easily place a pair of parallel poles into the structure, where the ends of the two poles are supported on the near side by the two closest vertices and the far ends of the pair of poles are supported at the two vertices at the furthest edge opposite. Looking at the wire mesh dodecahedron and picture two other pairs of parallel poles with their ends supported at the vertices of the other two edges on the Z and X axis’s – the two yellow poles crossing above and below the mid elevation and the other pair are (orange) vertical poles with the tops held at the roof peak vertices.

The compression members lay parallel and astride of the center of dodecahedron. We could place a total of 6 poles, consisting of three pairs in parallel, each pair perpendicular to every other. The next page in this section (links at the top and bottom of the page) shows the Front Cross Section where the poles crossing the middle of the structure that form the Main Floor are aligned but the pair of poles which are the principal vertical columns are plainly visible.