Chapter 2 of 24
Mannheim Multihalle, 1974: Structural Model
The next project, which I think was easily the most unusual project that I've ever worked on, was the Mannheim Multihalle for the Mannheim Bundesgarten show in 1974. This was designed by Frei Otto and he had developed the idea of building on a dome using a regular grid of timber laths spaced at 50 cm in both directions. And to develop the form of this he used a hanging chain model after the style of Gaudi; the idea being that when the building was completed and built the right way up, it had a moment free structure, so that the shell was theoretically in pure compression. Frei brought his friend Ted into the job. The engineer they had in Germany had to admit that he was unable to calculate the strength and stability of the timber shell. So we were asked to take over the role and it was quite a challenge. At the time that we took over, the contractor for the timber work had already been selected and they were all set to start work. The first thing we did was to make a model, a structural model out of Perspex lathes and put some loads on this, to try and ascertain by direct modelling what the buckling capacity of this shell was. For the construction that was intended, we discovered that the buckling capacity was the same as the self weight. So there followed an intense period of development to increase the stiffness of the shells, by doubling up the layers of the masts and the layers of the laths, adding the components, diagonal ties, onto it until it became satisfactorily stiff. The project was very interesting because of the use of models in the development of it.