Some call it Mandala Roof or reciprocal frame. That describes a load bearing principle known since centuries. Using it one can bridge a span wider than the length of each beam by connecting these elements at the end in an arrangement that allows the bending moment to run continuously through the framework.
One main research topic at the chair of Structural Design at the Faculty of Architecture at University Kassel is the development of parametric tools for different usages. Particularly in combination with the material timber this load bearing principle seemed to promise advantages. Guided by Prof. Manfred Grohmann and Dipl.-Ing. Asko Fromm the students Andreas Günther and Mischa Proll started with this principle and developed it further to allow to use it for theoretically any double curved spatial structure. The programs calculates the length of all beams and the detailed position and geometry of all cuts and connecting bolt-holes. Before all these data for production become necessary the geometry is exported into a calculating program which checks the structural behavior and an optimization can be done.
As part of his master thesis Mischa Proll transferred this workflow to a demonstration building using a very fruitful cooperation with the education center of the German Carpenter Association based in Kassel. The data generated by the program was used by a group of young carpenters to transfer in total about 2.5 m³ of timber with the dimension 100 by 100mm into the 180 beams of the framework using a numerically controlled cutting machine. After a kind of nesting the machine cuts all the beams to the appropriate length. Within the same step all the 324 cuttings are milled into the timber from both sides. This was arranged in a way the cross-sections only are weakened at the end of the beams. With the help of the same group of young carpenters the demonstration building was finally erected at University Kassel.