A space frame is a truss-like, lightweight rigid structure constructed from interlocking struts in a geometric pattern. Space frames usually utilize a multidirectional span, and are often used to accomplish long spans with few supports. They derive their strength from the inherent rigidity of the triangular frame; flexing loads (bending moments) are transmitted as tension and compression loads along the length of each strut.
Most often their geometry is based on platonic solids. The simplest form is a horizontal slab of interlocking square pyramids built from aluminium or steel tubular struts. In many ways this looks like the horizontal jib of a tower crane repeated many times to make it wider. A stronger purer form is composed of interlocking tetrahedral pyramids in which all the struts have unit length. More technically this is referred to as an isotropic vector matrix or in a single unit width an octet truss. More complex variations change the lengths of the struts to curve the overall structure or may incorporate other geometrical shapes.
Space frames were independently developed by Buckminster Fuller in the 1950s and Alexander Graham Bell around 1900. Bell's interest was primarily in using them to make rigid frames for nautical and aeronautical engineering although few if any were realised. Buckminster Fuller's focus was architectural structures and has had more lasting influence.
Space frames are an increasingly common architectural technique especially for large roof spans in modernist commercial and industrial buildings.
Notable examples of buildings based on space frames are:
- the airports of Foster Associates, for example Stansted Airport
- I. M. Pei's entrance Louvre Pyramid.
- the roof of the Rogers Centre by Rod Robbie and Michael Allan
- the roof of McCormick Place East in Chicago
- the Eden Project in Cornwall, England
- the Biosphere 2 in Oracle, Arizona
Larger portable stages and lighting gantries are also frequently built from space frames and octet trusses.
Tubular space frames are also widely used in the production of modern motorcycles and automobiles (and NASCAR race cars are exclusively built from spaceframe construction), but monocoque car bodies have been more common since the 1950s.