Capturing the incalculable

During the fifties and sixties structural research, particularly into thin concrete shells achieved results that are still unsurpassed. New materials, techniques and methods of calculation supported this typological and expressive innovation characterized by a synthesis between structure and architectural expression. Some engineers used mathematical formulas to describe the forms of the structures and their behaviour; others revelled in physical modelling to determine the form and subsequently investigate its stability. This paper intends to investigate the case of some thin shells build by Heinz Isler in the sixties and seventies and their behaviour in time. Since structural, architectural and constructional research is concentrated in a single building, the methods of repair, maintenance and reuse cannot be generalized. They have to be specific, not only with respect to the vicissitudes of each structure, but also to preserve the complex meanings these buildings embody.