Shell Sellers, The International Dissemination Of The Zeiss-Dywidag System, 1923–1939

No history of modern building construction can avoid making reference to the ZeissDywidag (Z-D) system. It will tell in brief the story of a nondescript test planetarium that had been erected 1922/23 on a factory roof in the Zeiss works at Jena, Germany, and that became the cradle of modern thin concrete shell construction. It will furthermore narrate how the building company Dyckerhoff & Widmann (Dywidag) developed out of this prototype within a couple of years an array of different shell constructions that gained world-wide fame such as the Frankfurt and Leipzig Market Halls. And, it will usually mention their planers, in particular Franz Dischinger and Ulrich Finsterwalder – names who are well-known to engineers dealing with thin shell constructions until today. Despite this extensive reputation, the Zeiss-Dywidag system usually is depicted as a significant contribution of the “German School” of engineering that – notwithstanding its fame – mainly was of local importance for thin concrete shell design. Consequently, no thorough study on the Zeiss-Dywidag system’s influence on the early international development of thin concrete shell construction has been carried out so far. An important process of knowledge transfer during the beginnings of thin concrete shell construction therefore has widely fallen into oblivion. This paper wants to recall the fact that there were successful efforts to promote and establish the Z-D system far beyond the German borders. It describes the global dissemination of the Z-D system before the outbreak of the Second World War, which gave a vast number of engineers on four continents a first possibility of gaining practical experience in the erection of thin concrete shells. Furthermore, it reveals that the underlying concepts were acting as important stimulators for a world-wide growth in the examination of shell theories. 1 Brandenburgische Technische Universität Cottbus Senftenberg, PF 101344, D-03013 Cottbus, may@b-tu.de Shell sellers. The international dissemination of the Zeiss-Dywidag system, 1923–1939 5 International Congress on Construction History INTRODUCTION “Very little [. ] about the international use of this construction type has become known to the public, even though it has been widely applied in most countries around the world. ” Hubert Rüsch (1939) The beginnings of building with thin concrete shells can be traced back to the nineteenth century. However, the international historiography studying this building type usually begins with a nondescript experimental planetarium erected 1922/23 on the roof of a factory building belonging to the optical company Carl Zeiss at Jena. This prototype developed by Zeiss engineer Walther Bauersfeld in cooperation with the building company Dyckerhoff & Widmann (Dywidag) boasted of a shotcreted network dome. The structure was essential for the future development of shell construction: For the first time current theoretical knowledge pertaining to the membrane theory from the field of applied mechanics had been implemented into practical building with reinforced concrete. THE ZEISS-DYWIDAG SYSTEM: A GERMAN SONDERWEG? Based on the experience derived from this pioneering structure, it took only a few years of a fascinating interplay between theory creation and immediate practical implementation to generate the fundamental knowledge for shell construction. Crucial in this process was the development of the long barrel shell, initially driven by Dywidag’s senior engineer Franz Dischinger, but subsequently ceded to his assistant Ulrich Finsterwalder (cfr. May 2012). Its usability for roofing large areas was soon impressively demonstrated with the Frankfurt Market Hall (1926–28). Wide attention attracted also Leipzig’s Market Hall (1927–29), as its two octagonal shell domes set a new world record span for massive domes. An experimental translation shell with synclastic double curvature on a square plan construction, built in 1931 on the Dywidag premises, was another instance to impress engineers world-wide. The photo of Dywidag’s staff on top of the 1.5cm-thin roof became a stock image in the historiography of structural engineering. Yet, this is also where the scientific narrative of the shell system Zeiss-Dywidag (Z-D) usually ends. Literature on shell construction regularly proceeds from here to works of Eduardo Torroja and Robert Maillart or – to a lesser extent – to achievements by Fernand Aimond or Bernard Lafaille in the 1930s. Skipping the 1940s, the story goes on with Félix Candela’s early designs from around 1950, usually seen as the prelude to the genuine epoch of shell construction. There are very few exceptions to this virtually canonic account, which implies the Z-D system became extinct without producing real offspring. Among these David P. Billington’s ample work is most notable, although he mainly emphasized the contrast of the Z-D system as a product fed by theory with the former Dywidag engineer Anton Tedesko’s approach towards shell design, which he acclaimed for relying much more on intuition and experimentation, instead. In fact, one has to concede that the path of the Dywidag engineers – paved to a large extent by mathematics – remained somewhat unfamiliar among structural engineers. Consequently, many of them considered the highly complex calculation of Z-D shells “a sort of transcendental mystery only divested by the German school” (Pizzetti 1958). FIRST INSTANCES OF INTERNATIONAL RECEPTION Despite this certain reluctance already the first Z-D rotational shells impressed the international engineering community. They were seen as ultra-modern and thus ideal envelopes for the