Parametric Engineering of a Historic Timber-Gridshell-System

In the 1920's, Friedrich Zollinger invented a grid-shell-system, that consists of only two types of timber "lamellas". These lamellas are connected by steel-pins and shape a barrel roof. These roofs are material efficient and easy to erect, which exactly met the requirements of that time. After a very successful decade, the rising labour costs and uncertainties about the structures stability made it slowly disappear.Even though the historic system is already very material-efficient, the design of the traditional system is based mainly on geometric relationships. It was generated by planning a 2D-grid and wrap in onto the 3D-barrel. In this way it was easy to make drawings of the components for manufacturing. The statical analysis of the resulting, intersecting helix-curves were difficult to calculate, besides further difficulties with the mechanical behaviour of the steel-pin joints. In former times no structural optimisations have taken place. Nowadays it is possible to implement the methods stated above to optimise these structures. In the following paper a parametric definition and an optimisation process are presented. The optimisation is done with an evolutionary algorithm. Due to the developed parametric design analysis of the Zollinger-system, it is possible to show further material savings and to reduce production inhibitions.

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