Heinz Isler's Shells

Presented & published at IASS 2015 Symposium

University of Michigan



Robert le Ricolais' influential structural engineering work from the 1960's was guided by his belief that “The art of structure is where to put the holes”. The paradox describes the removal of material that weakens a structure but also makes it lighter, thus making it more efficient. In the case of continuous shell structures, a perforated shell poses a unique opportunity for interdisciplinary integrated design since providing the apertures introduces daylight to the building, but at the same time alters the force flow in the structure and affects its structural performance.

Heinz Isler is an engineer who has designed extremely efficient shells with excellent performance over time. Considering his works, there are a few shell structures which have one or multiple apertures, mainly designed to introduce daylighting into space. But how have these apertures influenced the force flow and structural performance of the shell? What daylighting levels have they provided for space? And by manipulating the size and number of these apertures, how may the structural and daylighting performance of a shell vary?

This study intends to look at a perforated concrete shell designed by Heinz Isler and assess its structural and daylighting performance. Then, the size, number, and location of the openings is altered in order to observe the effect on the structural and daylighting performance of the shell. Rhino and Grasshopper are used as the modeling platform, while Karamba, which is a plugin for Rhino, is employed for assessing the structural performance, and the DIVA plugin for Rhino is employed to assess the daylighting performance. Finally, a comparison between different topologies is made using different numeric indicators. For structural performance, deflection, weight and maximum von Mises stress levels are considered, along with Daylight Autonomy on horizontal and vertical planes as the daylighting numeric indicator. The goal of this comparative study is to demonstrate trade-offs among various performance criteria, regarding the relation between topology, structural performance, and daylighting performance, and may be used by designers who consider multiple performance criteria in early design phases.

Credits: Niloufar Emami