Pioneered by Russian Constructivist artists in the 1920’s, “tensegrity” refers to a class of structural systems that allocate tension and compression so that solid matter appears to float in a tensile network. The word itself was coined by Buckminster Fuller as a portmanteau of the phrase “tensional integrity.” Because of their incredible structural efficiency, tensegrity systems have been the subject of mega-structural utopian speculation at the fringes of architecture, such as the “Cloud 9” floating city project proposed by Fuller.
Perhaps as a result of this lineage, tensegrity systems have been co-opted by a kind of high modern discourse that privileges efficiency, balance, cellular repetition, and platonic forms. In this mode of thinking, tensegrity structures are valued for their purity, the way in which compression and tension are separated and are resolved into rational forms at the macro-scale. The strictness of this scheme has resulted in a problematic interface to the messiness of real architecture as designers attempt to accommodate complex programs and forms within the regime of the “pure” system. In other words, tensegrity is boring.
As the purity of this scheme is loosened, however, tensegrity structures can become sophisticated computing devices that allow complex exchanges between tension and compression to emerge. With this looseness also comes a shift in values. The pleasure of a “pure” or “perfect” tensegrity system is in observing the spatial array of tensile and compression forces: the beauty of being able to visually trace familiar engineering concepts in counterintuitive arrangements that seem to float. By contrast, the pleasure of a loosened or “polluted” tensegrity is in the way tension and compression are control devices that provoke the development of new morphological and material systems. Put another way, tension and compression become interesting for the way they can do work that exceeds a structural capacity, but is at the same time driven by structural logic. In this way, experiments with matter can become “live” and “active,” energized by the activity of physics at play in the system. It’s time to reclaim tensegrity from the nerds.
We’ve been discussing this topic on and off on the geodesic listserv for a few years. For buildings and bridges, a pure tensegrity seems to make little sense. Tensegrity makes more sense when weight is at a huge premium: deployable masts for satellites, etc. Another example: a deployable bridge for a Mars expedition: http://vimeo.com/4240683 .
Sailboats are also a great example of a semi-tensegrity structure. Tensile forces are used to control the structure, but a pair of beams — the boom and the mast — touch each other. I could imagine the mast/boom constructed with tensegrity masts, but it would be a convoluted and probably a fragile structure.
The biggest reason for drawing the distinction is that there are certain structural behaviors that would apply to a true tensegrity but not for the semi-tensegrity structures. A true tensegrity is viscoelastic; Fuller describes that behavior in 724.32 – 724.34 of “Synergetics” (available online at rwgrayprojects.com ).
I deal with biological tensegrity structures: our musculoskeletal system is a tensegrity. This was pioneered by Levin (biotensegrity.com). Modelmaker Tom Flemons makes functional anatomical models (intensiondesigns.com). Bodyworker Tom Myers created a tensegrity-oriented mapping of our muscles in his book “Anatomy Trains” (anatomytrains.com).
I don’t think better or worse of tensegrity structures if they’re not a pure tensegrity. I am grateful for the ingenuity of architects to incorporate tensegrity in their designs. I’m certainly grateful for the building and opening of the Kurilpa Bridge.
Agreed. Purity as a criterion for design in tensegrity systems seems like a dead-end: we can catalogue all of the possible tensegrities that can be inscribed in prisms, spheres, and helical bounding geometries, but then what? Tensegrity becomes an encyclopedia of options, not a design principal. A more general approach — allocating tension and compression to separate ordering systems in a structure — seems to be more productive, allowing tensegrities to occasionally sacrifice purity in order to find a better “fit” with the demands of architecture and materiality. Tensegrity in biological systems seems like a particularly interesting case study because structural principals at play in the life sciences are often complex and excessive (in a good way); complex in terms of geometry, and excessive because material efficiency does not always appear to be the determining factor in how they emerge.
Wonderful debate, I summarized it to bring it more exposure here: http://tensegritywiki.blogspot.com/2010/07/clean-and-dirty-in-tensegrity.html
Thanks for the re-post! We’re always interested in revisiting this debate.