simple well-known four struts X-module architecture series


Tensegrities have quite a few characteristics that make them attractive for construction building. For instance, one can "capture" a lot of space with only a few masts and cables and this makes it a very economic construction technique. These masts and cables can easily be send to the construction site where the parts can be assembled as some sort of do-it-yourself kit. In the article Mechanics of Tensegrity Prisms Irving J. Oppenheim writes: "Tensegrity prisms can be totally self-erecting from a low-volume bundle by tensioning the last cable. Such a capability would be useful for constructing temporary structures."
The module structure of tensegrities seems to make them fit for the creation of giant structures, like domes and bridges and the use of cables makes these structures resilient and very qualified to resist any violent nature attack like earthquakes and hurricanes.
In his dissertation Valentín Gómez Jáureguigives a complete overview of all advantages tensegrity structures have compared to conventional building techniques. In all fairness Jáuregui does not forget to mention the disadvantages as well, like the complex force distribution in the structure and the complicated mast - cable connection. But tensegrity specialists like Anthony Pugh, Rene Motro, Robert Skelton, Ariel Hanaor en Robert Burkhardt have seen enough reason to make thorough studies of tensegrities and their architectonic possibilities.
A few studies concern the applications of tensegrities in special circumstances. For example, Anders Sunde Wroldsen has written a dissertation at the Norwegian University (Marine Technology) and in his abstract he writes: "Our motivation for starting tensegrity research was initially the need for new structural concepts within aquaculture having potential of being wave compliant." Gunnar Tibert has written his doctoral thesis about "Deployable Tensegrity Structures for Space Applications" at the University of Stockholm. The pictures below are from his dissertation and show a foldable antenna.

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Pictures by Gunnar Tibert: Folding a tensegrity antenna

Just after the invention of the tensegrity by Kenneth Snelson, it was not Snelson but Buckminster Fuller who had great plans with this construction technique. The picture below shows one example of his believe in a great future for tensegrities.

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This dome was build by "Bucky" in 1953. It is clear that the dome is constructed in a hall. Two man, I'm not sure who they are, stand in this dome and I don't know what they do there, but maybe they draw the attention away from something else in the picture. Something far more important: It is hard to see, but at the top of the picture one can distinguish a very small vertical line. That line is a cable that connects the top the tensegrity with the ceiling of the hall. The cable is there with only one purpose: to prevent the structure to collapse. It is the nearly invisible proof that the structure is not able to lift it's own weight. One must conclude that a very promising construction method was tested on large scale here, but the experiment failed.

But from an historical point of view it is an interesting picture that shows us that Fuller did experiment with tensegrities extensively (allthough he had not invented the word "tensegrity" yet). In that same period, Snelson did nothing with tensegrities: he had moved to Paris in 1951 to paint at the Academie Montmartre and when he returned to the US in '52 he started to work as a cameraman in New York. In fact, Snelson, who did not start making tensegrities again until 1959, has never seen any practical use in a tensegrity other than an artistic value. He has been very clear about domes in an article by John Coplans, 1967: "He (Fuller) absorbed my idea into his geodesic domes, the spherical ones, and I have never had any involvement with that aspect.". In two e-mails to Jáuregui in 2004 (which is half a century after Bucky build this dome) one can still feel some emotion: "Bucky's "tensegrity dome" or sphere is by it's nature as soft as a marshmallow." and "..You say about Fuller's domes: "However, the final application of tensegrity was not as successful as he thought it would be; he was never able to produce a Tensegrity dome which could cover the whole city, as he intended." My God, man, even his cigar-strut "Geodesic Tensegrity Dome" you show sitting in that workspace could barely hold itself up. Despite all his celebrating of triangulation, his tensegrity domes are not triangulated and therefore are as shaky and floppy as a Tensegritoy.."

In retrospect one can say that the dome construction built in 1953 had a poor design. This dome is a so called "single layer dome". It has only one shell of cables and all these cables are at the outside of the dome. A much stronger design is the "double layer" type, where there are two shells of cables: one at the inside and one at the outside of the dome. All the struts and another series of cables are between these two shells. A double layer dome is stronger mainly because of it's design: the dome layer is simply thicker than a single layer dome.

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Above a design by Robert Burkhardt. It looks very complex but it is probably a very solid double layer construction. The picture is on the front side of his study A Technology for Designing Tensegrity Domes and Spheres.
Despite the charme of tensegrities and all of its interesting characteristics and despite all the efforts made by Fuller, Burkhardt and others, one must conclude that there exists no real tensegrity dome with a practical application yet. The Olympic Stadium of Seoul (1986) designed by Geiger en the Georgia Dome (1992) by Levy and Weidlinger Associates come close but are not "the real thing" because they have a major compression component at the outside of the construction (so they look more like a bicycle wheel). Also other architectonic constructions like the Kurilpa bridge in Brisbane are a nice attempt but not more.

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Kurilpa bridge in Brisbane Australia built in 2009

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A simple "single layer" dome. In this case it is nothing more than an unfinished ball.

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A "double layer" dome seen from the top. One can see the thickness of the wall of the dome.

Not very successful in the architecture of mankind, tensegrities may play a major role in the architecture of nature.
In this small movie you can see a conversation between Tom Flemons and Stephen Levin where Stephen explains that according to his biotensegrity theory this tensegrity-icosahedron is the final element or the building block of nature.
Stephen Levinis an orthopedic surgeon with great interest in Biotensegrity. In the movie he uses Tom's tensegrities to explain that an "icosahedron-tensegrity building block" is different from a normal brick. When you build a wall with normal bricks you just pile up the bricks and there is no problem to stop somewhere halfway the building process. Half a wall is just functioning as half a wall, no more no less. Also all the bricks in half that wall are independent. None of them "knows" that the wall is unfinished.
Building an organism with "tensegrity-icosahedron-bricks" is a different thing, because all the tensegrities are interconnected. This means that half an organism can not function as half that organism, because every "tensegrity-brick" needs and feels all the other "tensegrity-bricks". For example a force on the outside of the organism will affect what's going on at the inside.
In order to understand what Levin means you could buy a skwish and experience why a tensegrity-icosahedron is an entirely different building block compared to a normal brick. Then you feel that when you push on a strut, the entire structure deforms. If you don't want to buy one, you can make an icosahedron-brick yourself. You can find the strut-string ratio at the bottom of page well-known.

Tom Flemons has his own interesting site called with beautiful tensegrity models like a vertebral mast and a leg-foot-construction. On the site also an essay (20 pages) called "The Geometry of Anatomy - the Bones of Tensegrity".
In this essay Tom Flemons describes his practical search for tensegrity models within the human body. Here, one passage from his essay: "If a bone and its attachments (e.g. the femur) can be described as a tensegrity that interacts with another (e.g. the tibia) then any joint can be seen as the interface between two tensegrities. Taken together they form an articulating tensegrity that is greater than the sums of their individual behaviours. Because the components of tensegrities (compression and tension members) can be thought of as composed of smaller tensegrities, the body is seen as fractial and hierarchical. The body as a whole is always synergistically involved in the actions of the peripheries. Equally, articulations of succesive joints such as fingers, wrist, elbow, shoulder do more than just add up- their effect is multiplied."
Also the essay includes beautiful pictures. For instance one in which two tensegrities are projected on the bone structure of a human knee. In the end of his essay Tom says: "What's next? I've tried to convey some of the inner workings of tensegrities in this cursory look at applying Biotensegrity to the geometry of anatomy. My observations and ideas are speculative and my models approximate; more needs to be done to fill in the details. As the investigation is just beginning, I am interested in how this will be received over time in the larger medical community. Owing to the power of the idea and thanks to writings and presentations of Fuller, Snelson, Ingber, Levin and many others, it appears certain that tensegrity ideas are going to influence the next generation of scientists and artists..."
Stephen Levin's site www.biotensegrity.comis also worth reading and it is nice he refers to another biotensegrity-icon: Donald Ingbar.

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Picture of an art piece made by Kenneth Snelson. This is what I imagine when Ingber talks about tensegrity constructions in a living cell (allthough I realize that reality is a bit more complex).

Snelson is one of a few men who built giant tensegrity structures. I guess, he knows best what it takes when tensegrity becomes architecture. In an interview by Angela Schneider he describes his strugggles building one of his structures, the "New Dimension" as follows: "..The photographs tell the story, I think, but minus all the cursing... I wish I could say that it went as smoothly and easily as it looks, perhaps, in the pictures. Unfortunately it is never easy with my structures, especially if they are as complex as these. If I have few imitators, this is one of the reasons. Three of us, sometimes as many as six men fought with the forces in "New Dimension" while it was going up. It is like taking on a colossal, dead- weight wrestler or an enormous mind-bending jig-saw puzzle constructed of a series of booby-traps. Sometimes we spent an hour or so just to arrange for the introduction of a single pipe. After finally overwhelming the monster with our brave determination and strength we see that we have won. Only then does someone discover that a cable is twisted over something in the wrong way and we must do the whole act once again; with feeling."

Personal note
I visited the Needle Tower II in the sculpture garden of the Kröller Müller museum in the Netherlands once, and I had the guts to give one of the ropes at the bottom of the construction a firm push. I must say I startled a little by the effect it gave. The whole structure, especially the top of Tower shook heavily. On one hand it was nice to get the confirmation that within a tensegrity "all is one", everything is connected, but thanks to this one push I'm very reserved about the practical applications of a tensegrity.
But if I had to choose a type of tensegrity that could have technical applications then it would be this "bridge" configuration:

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Quite a unique tensegrity contruction. More information about this concept can be found onbridge.

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The "wall" of a double layer dome.

Marcelo Pars