Geodesic Lines for Timber Rib Shells


Funding: EPFL, FNS

Status: Completed, 2008 – 2012

Doctor: Claudio Pirazzi, engineer, IBOIS EPFL

Thesis director: Prof. Yves Weinand, architect and engineer, IBOIS, 

Partners: Prof. Peter Buser, mathematician, GEOM/EPFL, Dr Roland Rosznyo, mathematician, GEOM/EPFL, Vial SA, Fribourg


To build rib shells with straight planks, the grid of the ribs has to follow a specific geometry: the geodesic lines. Geodesic lines on simple, regularly shaped surfaces can be determined by analytic means. On cylindrical surfaces, the geodesic lines correspond to helices, and, on spheres, to the great circles. On free-form surfaces, currently enjoying great popularity in contemporary architecture, the determination of geodesic lines is much more complex. In order to satisfy this demand and to improve automation of the production process, the GEOS software was developed in close collaboration with the Laboratory of Timber Construction (EPFL/IBOIS) and the Chair of Geometry (EPFL/GEOM). This software calculates grids of geodesic lines on free-form surfaces and provides all the geometrical data necessary for computer-controlled milling.

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