/// Tensegrity - WS 2002/2003
/// Constructive seminar (Prof. Mirko Baum)
/// Chair of constructive design

Subject

The complementarity of compression and tension is a principle adopted from nature which is stabilizing systems. A classic example for its application is the spokewheel. From the Ferris wheel of the 'Prater' in Vienna, ultra-light skeletons of airships to modern cooling towers and large ceilings of halls we come across the system of the spokewheel, where there are only normal forces compression and tension. R. Buckminster Fuller, a revolutionary pioneer of this construction method, speaks of "tensegrity structures" while thinking of systems the balance of which are maintained by the diskontinuity of compression and continuity of tension. "Tensegrity", Fuller's own neologism, is put together by "tension" and "integrity".

Appointment

The appointment was to present constructive tensegral ideas concerning a subject chosen by ourselves (beams, masts, cupolas, 3d-static units, etc.). The aim is to pass through an abstract approach to the subject and develop an understandable and working model.

The work shown here was done by Felix Thies, Heike Zieher and myself. The subject was a dense method of mating octahedrical tensegral modules which can be used to construct surfaces or domes.

Concept

A problem tensegral constructions often struggle with in practical application is the fact that on the one hand this principle is light and saving material but on the other is lacking the stiffness and characteristics of absorption necessary.

One approach to counteract these problems is to try to develop tensegrity-constructions more dense.

Apart from conventional methods of mating octahedrical tensegral modules, there is another one more complex providing a kind of double-layered construction. For this the modules are formed like the upper and lower triangle of tension are different in size. Afterwards the new octahedrical tripods are put together to form a construction in which the individual modules are directing towards the top and the bottom alternately. The resulting structure is much more dense than comparable tensegrity structures.

Construction

We were using aluminium tubes for the model. They are used as compression members. For the cables it seemed to make sense to use a system that provided us with the possibility for experimentation, i.e. making easy changes in length. Hence there is a kind of tensioning system that is commonly used with tents. The joints are made of ordinary small lugs the thread of which are put into the tubes. They cannot fall out because of the tension pulling into the opposite direction.

The model shows a very small part of a tensegrity net or a possible construction of a dome. A curvature of the surface would be reached by different lengths of the cables at the upper and lower side.