Concrete Thin Shells in the Sixties. Construction and Long-Term Behaviour

The new globalised and mass society at the end of World War II posed new challenges for architects and engineers and offered new stimuli. Double curvature structures (membranes and shells) in reinforced concrete were a frontier in the field of typological, spatial and expressive innovation. New materials, new technologies and new production systems supported research into shape-resistant structures that led in various directions. Two of the leading figures were the swiss engineer Heinz Isler and the italian Dante Bini: the first with his methods called “form finding” based on the use of physical modelling to determine the form and subsequently investigate its stability; the second with his research in the field of the industrialization of the construction process. These thin concrete shells, in which research into “limits” was a fundamental factor, have proved vulnerable to the passing of time. The analysis of the construction and monitoring of lifetime of these structures shows the distance between theoretical projects and construction of real shells. Despite the importance and authority of the leading figures who conducted research and built thin concrete shell structures, their destinies have been very different. Some have been demolished or considerably altered; others have been given careful maintenance and protection. Observing the behaviour of these structures with the passing of time offers an opportunity to reflect on the logic with which they were designed and built in a period of absolute formal and structural experimentation, besides placing the emphasis on fundamental aspects for the conservation and reuse of this fragile patrimony.