Design of a Construction made of Bamboo Poles

The Building of a Dome According to the Principle of the Grid Shell

The construction of the dome has presented architects with a great challenge ever since antiquity. At that time they built domes from stone (the tomb of Agamemnon, 1500 BC) or cast them from opus caementitium (the Pantheon in Rome, 120 AD.) and were thus continually searching for the ideal form while, although these basic materials were capable of bearing pressure they were not able to withstand tensile stress. Added to this was the question of constructing appropriate scaffolding since domes, like arches, can support themselves only once the keystone or thrust collar has been set in place.

A revolutionary development was effected with the invention of the tight connection- and pressure-resistant, reinforced and prestressed concrete with which, still on scaffolding and shell, especially beautiful domes were built measuring a mere few centimetres in thickness (the Palazetto dello Sport by P.L. Nervi, completed in 1957 or the elegant shell by Heinz Isler for the Deitingen motorway filling station in Switzerland, built in 1968).

Bauersfeld and Dischinger constructed the first scaffold-free reinforced concrete shell for the Planetarium in Jena by erecting a “geodesic dome“ made of steel poles and closing them with shotcrete, in 1922.

Based on the icosahedron and a combination of six and five corners, as familiar to us from the football, Buckminster Fuller further developed the geodesic dome into a light spatial structure, which can be covered with plexiglass or  transparent glass (the most well known being the US-Pavilion at the Montreal Expo, in 1967).

Even lighter and less complex domes can be manufactured according to the “salad sieve principle“, which has an evenly spread quadratic meshing, by hoisting up a meshed network which one can then spatially flex according to design and such that it’s meshed angles are altered. This well known principle, one recalls the material tents of the Nomads or the Olympic tent roof in Munich (1972), was further developed by Frei Otto and brilliantly demonstrated by the grid shell of the big Multihalle in Mannheim of 1975 and constructed of simple wooden slats.

Based on this principle, by using steel poles braced by ropes Jörg Schlaich and his team constructed numerous, very light grid shells covered with glass (e.g. the Museum für Hamburgische Geschichte Hamburg, in 1989 and the Central station – Lehrter Bahnhof, Berlin, 2006).

In the workshop, the history of shell construction will be recapitulated and, at the same time, a grid shell geometrically designed, replete with an elliptical floor plan measuring 7,5m / 5,3m and 3m high, made of bamboo poles and covered with an appropriately tailored tarpaulin – homage à Frei Otto, the great master and inspirer of modern ecological lightweight construction.

For this, the bamboo poles with a mesh width of approx. 50 centimetres, cut exactly to the right length and placed on the ground, must be flexibly attached at their pin-joints – a detail which has yet to be developed.  Similarly, the correct cross-section size of the poles must be tested in such a way that, on the one hand, they do not break when hoisted while, on the other, they are not so thin that they buckle later – in short, an experiment which fully engages our faculty of imagination and artistic skill even though it is by no means certain whether we will succeed. If it should fail, then we shall have at least learned a great deal whereas, if we do succeed, we shall be rewarded with a beautiful and exceptionally light dome of which we can at once take possession and bequeath to future workshops for further use.

Jörg Schlaich