Heinz Isler’s Form-Finding Models for his “HIB” Shells: Between Experiment and Design

The Swiss engineer Heinz Isler (1926–2009) is among the most prominent figures in shell design. Thanks to a form-finding approach based on the use of physical models, he designed and built many shell projects in reinforced concrete. His unconventional structures still represent an important source of inspiration for today’s structural engineers. The paper reconstructs Isler’s experimental method by looking at the multiple physical form-finding models he developed for his tennis hall shells. Designed for the first time in 1977, they became one of Isler’s most successful shell typologies, promoted as “HIB” shells in Switzerland. Despite their apparently simple shape, Isler produced the largest number of physical form-finding models for this specific shell type. Their double symmetry challenged his design method: the highest precision was needed to avoid any irregularities in finding the appropriate geometry. By studying the original materials stored at the Heinz Isler Archive (gta Archives, ETH Zurich), details about Isler’s experimental approach to the conceptual design of his shell structures will be revealed for the first time.