BY CHRISTIAN MEYER AND MICHAEL H. SHEER

The modern era of thin concrete shells began in 1922 with the construction of a 52-ft-diameter (16-m), 1.2-in.-thick (30-mm) reinforced concrete dome in Jena, Germany.1 This revolutionary structure resulted from a collaboration between Walter Bauersfeld, of the German optical company Zeiss, and Franz Dischinger, of the German engineering firm Dyckerhoff and Widmann. Their design and construction technique was introduced to the U.S. by Anton Tedesko, another Dyckerhoff and Widmann engineer. In 1936, while consulting with the Chicago firm of Roberts and Schaefer, Tedesko designed the first large thin concrete shell in the U.S.: a 232-ft (71-m) span, 340-ft-long (104-m) barrel shell for an ice hockey arena in Hershey, PA.1 In the three decades following the introduction of thin shells in the U.S., a number of innovative designers, such as Pier Luigi Nervi (Fig. 1), Eduardo Torroja, Vasilii Vlassov, and Felix Candela (Fig. 2), advanced the state of the art by introducing new design theories and construction techniques and experimenting with shells of different forms. It was during this time that a variety of landmark shells of double curvature, such as hyperbolic and elliptical paraboloids, were constructed (Fig. 3 and 4). Based on the number and variety of shells built from the 1920s to the early 1960s, this period can be considere