The Invisible Beauty of the Zeiss-Dywidag Domes: Topology Optimization of the Triangulated Rebar Grids

The Zeiss-Dywidag system was a pioneer in the history of thin concrete shells, which impacted and advanced theory and praxis worldwide. This study explains its relevance for the history of gridshells: the first ever built Zeiss-Dywidag dome started out as a geodesic gridshell, sprayed over by concrete. Walther Bauersfeld abandoned his own ingenious design for the first Planetarium in Jena in favour of a lamella-type topology for the equally self-bearing reinforcing grid of the later Zeiss-Dywidag domes. We reconstruct the optimization of the geometry and tessellation of the first built example of the latter, the Schott dome, and suggest possible motivations for the change. Bauersfeld’s strikingly advanced theory of equivalent membrane shells, which played an essential role in the process, is published here for the first time. The significance of a unique benchmarking parameter, the so-called bar density (D-value), introduced by Bauersfeld is investigated. Its applicability to assess geometric fitness is assessed by a comparative study of selected grid topologies and geometries.