geodesic rebar dome - a cheap & useful dome design
top view
[rebar1top.gif 8k drawing]

side view
[rebar1side.gif 8k drawing]
one great semi-circular arch
[rebar1strut.gif 8k drawing]

the geometry of this framework is based again on a one-frequency dodecahedral tensegrity.  this is a much cheaper & easier method than using EMT conduit struts, and more permanent...

for this dome, steel rebars are curved into 5 great semi-circles, with a tail at each end for ground connection.  two more rebars with the same curvature (and no tails) are welded together to make up the great-circular base of the dome.

the overall size is easily scalable.  in this example (for ranjit) we'll start with 40-foot lengths of 1/2-inch to 3/8-inch rebar, and a great-circle circumference of 70 feet, giving a dome radius/height of approx 11 feet, diameter approx 22 feet, and floor area of 390 'square' feet.  the pentagonal and triangular faces will have 7-foot curved sides.

each arch is divided into 5 sections of 7 curved feet (plus a 2.5-foot tail at each end).  pairs of arches will meet at these section dividers, where they can be welded together via a small steel disk (about 3-in diam 3/16-in thick) between them.  exactly two rebars will cross at each vertex.

perspective view
[rebar1persp.gif 8k drawing]
welding the first two arches
[rebar1start.gif 8k drawing]

these 5 great circle arches provide basic strength for the dome, but it will be pretty bouncy, and the open areas inside pentagonal faces are rather large.  the pentagonal faces (especially the roof) can be subdivided / stellated as necessary with shorter sections of curved rebar struts welded at vertexes of the main frame arches.  for a practical example, see victoria's rebar dome.  still working on optimal designs and details for this...

cross-eyed stereo 3-d versions of above drawings
( how to view these stereograms - gently cross your eyes until you see 3 images instead of 2, then allow time for your eyes & brains to re-focus on the center image.  if you normally wear glasses, this might be easier without.  and if anyone wants wall-eyed stereo, email me and i'll be happy to add it to this page :)

top view
[rebar2top.gif 8k stereogram]
side view
[rebar2side.gif 8k stereogram]
perspective view
[rebar2persp.gif 8k stereogram]
welding the first two arches
[rebar2start.gif 8k stereogram]

for some ideas & methods of covering this frame, see other dome pages, below.  my next dome project is a rebar greenhouse, wrapped with 6-inch-square fencing to make a grapevine arbor for shade & shelter in the arizona desert...

drawings made with help from gamera the flying hyper-turtle, more drawings and photos in progress...
also see - victoria's rebar dome - small workshop domes - greenhouse dome 98 - webliography - dome cat