Early Mushroom Slab Construction in Switzerland, Russia and the U.S.A. – A Study in Parallel Technological Development

Alexander Kierdorf INTRODUCTION Each step in technological development has its specific conditions. How to find or create the best conditions is a permanent question for scientists, professionals, practical men as well as politicians. In periods of rapid spread and establishment of a new technology, we often can observe parallel developments under various conditions and relations. A striking example for this, taken from the field of construction and structural engineering, is the development of flat slab ceilings made from reinforced concrete. The mushroom slab system is widely regarded as the first genuine reinforced concrete construction, avoiding beam-and-girder systems (mostly identified with Francois Hennebique), replacing them with slabs on columns with extended capitals. This construction was called "mushroom" in America reflecting the form of the pillar, but also understood as "fast growing", signifying more the speed of execution than the spreading of the system. In Western Europe, this term was also adopted, whereas the more technical "beamless" or "downstand-beam-less ceiling" was preferred in Russia and also used in technical literature before WW I. The theoretical penetration of mushroom slab design is closely linked to the understanding of flat slabs, seen as elastic elements. Its full abstract mastery was reached only in the 1920s. Until then, stability had to be proved or at least ensured by tests and empirical data. The analysis and understanding of moments in the composite material of reinforced concrete, by calculation and by observation, provided a first basis for dimensioning, armature and construction details. The advantages of an integral system of columns and slabs without beams were obvious: By avoiding "caught" space between the beams, the same amount of usable, undivided space could be obtained at less height of each floor; lighting and ventilation were simplified; energy transmission and other equipment, as well as dividing walls could be installed much easier. Much expensive formwork was saved during construction. Architectonically, as it was claimed, the mushroom system resulted in a much more elegant, floating space with dynamic "growing" columns. Almost at the same time mushroom ceiling construction was being designed and realized in such different countries as Switzerland, Russia, and the United States. Claude A.P. Taylor from Minneapolis is the first to have executed a mushroom ceiling in 1906. Artur Loleit in Moscow

1793

started to use mushroom ceilings in 1908, and Robert Maillart from Zurich, having experimented since 1908, built his first mushroom ceiling in 1910. All three were known as innovators and pioneers in their home countries. The conditions under which they developed their "system" were strikingly different from each other: their personal status, their professional background, their regular activities as well as the possibilities of application. Also the relation to scientific institutions, the contacts and knowledge of or information about each other need closer study. In addition, it seems helpful to have a look at the journals and publications in Germany to explore the scientific basis and background and help make the situation more transparent and identify possible contacts and relations. CAP TURNER IN THE UNITED STATES Among several competitors, Claude A. P. Turner (1869-1955) from Minneapolis in Minnesota / USA was able to establish the most successful system of mushroom ceilings, first applied in 1906 (Gasparini 2002). Turner was a railway engineer and bridge specialist and founded his own consulting firm in 1901. In 1904/05 his first buildings with columns, ceilings and girders in reinforced concrete were executed and studied by him in detailed load tests. In the autumn of 1905, he published a first drawing of beamless slab design, showing mushroom columns and a four-direction reinforcement of the flat slab (Fig. 1). An armature detail for shear protection originally introduced the word "mushroom", which was soon transferred to the whole system. Although his concept was heavily criticized by established engineers, Turner the "outsider" managed to prove its reliability in tests and had a first brochure printed in 1909. The growing demand for a theoretical, analytical approach was only fulfilled by Eddy in 1913, when Turner had already designed around a thousand buildings (Fig. 2). Turner’s first design remained the exemplar for this type of construction and was used in several contemporary text books.

As a consulting engineer, Turner provided his method to any construction company and engineer who was willing and ready to use it and to accept his rights. He took patents in several, mainly English-speaking countries, and applications are even known in Australia. However, Turner never gave full information on his design principles; based on the Grashof theory on slabs, he also drew many of his details from empirical data. Typical for his design is the four-directional slab reinforcement leading to a critical concentration at the crossings, especially above the columns. Other engineers developed two-directional reinforcement and reduced the amount of steel used. A great amount of Turner's success was due to the reduction of formwork and the use of metal column head forms to save expensive workforce, a major commercial factor in the high-wage American construction industry. From 1910, Turner faced heavy attacks on his patent by competing construction companies that stopped his activities during World War I. Other systems had also managed to conquer part of the market, obviously profiting from the confidence Turner had created.

1794

After WWI, it was noticed with astonishment in Europe that mushroom ceilings dominated the reinforced concrete construction in America, yet still without a sufficient theoretical basis.

Figure 1. CAP Turner, details of mushroom slab construction, 1905 (Gasparini 2002, Fig. 6)

1795

Figure 2. Mushroom slab by Turner in a contemporary advertisement ROBERT MAILLART IN SWITZERLAND AND RUSSIA Swiss structural engineer Robert Maillart (1872-1940) is famous for his elegant and technically individual reinforced-concrete bridges (Billington 1997). After studying structural engineering at State Polytechnic (ETH) in Zurich, he worked for a private company. In 1902 he founded his own business as designer and building contractor for all kinds of reinforced-concrete constructions. Maillart's first known occupation with the mushroom system dates back to 1908 when he built an experimental construction at his company yard in Zurich. This and a second scale model construction enabled him to find missing data for the analytical calculations and their application to mushroom construction. The first commission was for a warehouse in Zurich, finished in 1910. Maillart took out a patent, ending in 1924, but did not publish his methods of calculation and dimensioning. Maillart's design approach has been reconstructed, showing that he used empirical methods to develop a design method that could not be developed using the scientific knowledge of the time, and would only first be achieved after the development of new calculation methods in the 1920s (Fuerst/Marti 1997). In practice, his mushroom slabs were much lighter than those that could be fully calculated at the time; only much later was it possible to provide the justifying calculations that prove his safety margins were sufficient. Maillart did not use the Grashof method for slab design, believing that, in important respects, it did not reflect the needs and the reality of his constructions. This also distinguished them from the

1796

widely-published American systems which he must also have known. Furthermore he used reinforcement in only two directions, which is clearly different from the American methods. As Maillart did not publish his mushroom ceilings after they were complete, he took no part in the scientific discussion of his time and his work was not reviewed. Whereas he is known for his bridge designs, this part of his work was only seen as a demonstration of his ability to create structural elegance. Among the countries into which Maillart extended his activities, it was in Russia where he saw his professional future and relocated there in 1914 (Stadelmann 2001). He had used the mushroom system for a warehouse in St Petersburg harbour in 1912, sadly destroyed in 2001 (Fig. 3). The construction of an enormous factory complex in Riga brought him and much of his equipment there in 1914. The Baltic metropolis, competing with St Petersburg as a major port, was dominated by a German-speaking elite and was home to a renowned polytechnic institute, that served as stepping-stone for many Western business interests in Russia.

Figure 3. Warehouse of the Gerhard & Hey company, St Petersburg; Robert Maillart, 1912 While spending the summer with his family on the Baltic, Maillart got stuck there when war broke out in August 1914. Building stopped, and many factories and institutions were transferred into the Russian homeland to evade German occupation. Maillart followed the AEG factory equipment to Kharkov in the East Ukraine and built a new factory for them. Nevertheless, the next commission – some buildings for the Kamenskoe Steel Mills (now Dneprodzherzhinsk) – could not be finished because of the civil war. Maillart had to flee and returned to Switzerland in 1919, totally ruined. Only in 1926, when learning that the origin of the mushroom system was attributed exclusively to the Turner in the U.S.A., did Maillart provide information about his early activities and revealed

1797

some of the important details. Anything else we know today has come mainly from archival material and later tests and analyses of his buildings. ARTUR LOLEIT IN RUSSIA Artur Ferdinandovitch Loleit (1868-1933) studied applied mathematics at Moscow University and started working in 1892 for a German-owned construction company in Moscow (Lopatto 1969). He soon became their chief engineer and technical representative. He worked with the Monier system and was responsible for all kinds of concrete constructions, especially arch bridges, and basement and church vaults. When the restrictions for the use of reinforced concrete in building were lifted in Russia in 1905, Loleit started to design industrial and other buildings for Moscow and its vicinity. Inside the technically and architecturally highly-ambitious Bogorodsk-Glukhovskoe textile factory near Moscow, designed by ambitious Moscow architect Alexandr Kusnetsov (Nashokina 1999), Loleit executed an experimental construction in 1907 with pillars formed like flutes and with circular skylights between them (Figs. 4, 5). This construction was quoted in the exhibition hall of the new wing of the Stroganoff decorative arts school (today the Moscow Architectural Institute: Marchi) in 1913-14. This was also an architectural design by Kusnetsov and the two worked together frequently over several decades. In March of 1912, Loleit presented "beamless" constructions at the regular meeting of cement specialists in Moscow; his lecture is not documented. In September of 1913, he again gave a detailed lecture on mushroom construction, this time in front of the Russian Society for Materials Research, but it was published only in 1916. Had it been published earlier, and had the International Conference on Materials Research planned for 1915 in St Petersburg not been cancelled because of WWI, Loleit would certainly have presented his work to a broader public.

Figure 4. Bogorodsk-Glukhovskaya manufacture, central part, 1907 (photo 2002)

1798

Figure 5. Bogorodsk-Glukhovskaya manufacture, central part, detail of column In his 1913 lecture, Loleit presented some mushroom slab constructions, notably the Tschitschkin dairy from 1910, and some textile and other factories which have not yet been identified, but which probably still exist. The construction is extremely light, fragile and wide-span; the column heads are curved and small (Fig. 6).

Figure 6. Reinforcement scheme by Loleit, published in 1913/1916

1799

His own drawings as well as photographs of construction sites show that he used a homogenous two-direction grid for the complete slab and a additional upper-layer grid above the columns, which could be prefabricated (Fig. 7). A second version also gives a two-direction reinforcement, characterized by short sections (Fig. 8).

Loleit also presented a calculation approach based on the Grashof formula. He discussed the proposals of German engineer Mayer from 1912, but he clearly insisted that he had developed his own method beginning with the study of the column foot in a factory design.

Figure 7. Second reinforcement scheme by Loleit, published 1915 (Lopatto 1969, fig. 19)

Figure 8. Beamless ceiling by Loleit in a textile factory, ca. 1910-12

1800

Three major, later applications by Loleit are traceable in Moscow. The military department store (1911-13, architect: S. Zaleski, destroyed in 2003) had beamless ceilings on circular columns in some areas, combined with other construction elements.(Figs. 9, 10).

Figure 9. Military department store ("Woyentorg"), Moscow, arch. S. Zaleski, 1911-13

Figure 10. "Woyentorg" while being razed, 2003

1801

The workshop wing of the Stroganoff school, already mentioned, was built in 1913-14 and has beamless ceilings on very thin columns (Figs. 11, 12).

Figure 11. Moscow Architectural Institute (Marchi), extension, arch. A. Kusnetsov, 1913-14

Figure 12. Marchi, extension, column without plaster on the second floor (photo 2005)

1802

The third case is a pair of multi-storey warehouses, built ca. 1914-15, one of which has beam-and-girder, the other beamless construction (Figs. 13, 14). This might have been a comparative demonstration, or just due to lack of time and forms.

Figure 13. Warehouse, Moscow, arch. A. Kusnetsov, ca. 1914-15 (photo 2005)

Figure 14. Warehouse, ground floor interior with beamless ceilings (photo 2005)

1803

When the joint-stock company was closed down at the beginning of WW I, Loleit started teaching and hardly again had the chance to design an extraordinary building. American and German theoretical approaches came into use, promoted by W. Keldysh. Loleit insisted on his "Russian" experience and methods, but in a public discussion could no longer succeed. Around 1930, Loleit tried to establish a completely new reinforced concrete theory, which was not accepted by the professional and scientific elite of the time. In the pre-revolution period, Loleit's position as a leading engineer and director of a big construction company gave him the opportunity to experiment and realize his developments. As an educated mathematician, he was also have been able to work seriously on solutions to the theoretical problems. There is no hint that Loleit's developments were legally protected in Russia, or that they were seen as the company's intellectual property. The German mother-company, the famous AG für Beton- und Monierbau in Berlin, probably never tried to exploit this method in Germany, knowing that it would not satisfy German building control requirements. There is also no hint that Loleit and Maillart knew of each other or even met. Maillart was not integrated into the Russian society; his clients in St Petersburg and Riga where out of reach of Loleit; their respective companies were not direct competitors. So it was possible that two commercial pioneers of the same techniques worked in Russia without getting in touch. Although the public lectures of Loleit coincide with the beginning of Maillart's activity in Russia, they were certainly not evoked by Maillart's presence; nor is anything known of a patent conflict. Loleit was almost forgotten until Soviet Russian historiography in the 1960s cold-war period discovered him as a hero of technological development. He was without a doubt a pioneer of reinforced concrete, but the lack of information in many areas makes it even now difficult to put him into his rightful position on an international stage. Most of his buildings are still to be identified and researched; the history of his company is hidden like other foreign engagements in pre-revolutionany Russia which did not possess a large, complex technical community comparable to Western countries. FLAT SLABS IN GERMANY It is an interesting question why in Germany, which was at that time not only one of the leading industrial countries, but was also, scientifically, the most active in reinforced concrete technology, no early mushroom ceiling constructions were executed. It was repeatedly stated that strict building regulations and the lack of a convincing theory were the main reasons. If this is true, this would mean that a high standard of regulation and scientific demands prevents innovation. In fact, German specialists were rather well-informed, and there was a constant interest in the developments in this field. The first mention of mushroom systems occur in the professional

1804

gazettes already in 1906. But immediately it was also already stated that German building regulations did not allow such construction, which sounded like a warning to all over-ambitious men of practice. Foreign engagement was equally limited by this situation. From time to time, proposals regarding flat slabs were published in Germany. The first detailed paper on mushroom construction was printed in 1912. Its author, Max Mayer, not only worked for Wayss & Freytag, one of the first and most successful reinforced concrete construction companies, but also took a special interest in American building methods. Although he described the practical advantages and possible theoretical solutions of the mushroom system, he saw no chance of application in Germany. So the German structural engineers established their "Pilzdeckenproblem" (mushroom ceiling problem), and began to propose calculation methods in the following years. Among these was work by Henri Marcus, chief engineer at the HUTA cement building company in Breslau, and Victor Lewe from Berlin. Their methods provided a basis for the most important changes in the 1925 reform of reinforced concrete regulations, concerning design calculations for flat slab and mushroom ceilings. But even in Germany, practical execution preceded theoretical penetration and administrative regulation. The first applications can be reported from Straßburg in 1912/13 (Züblin) and Hamburg 1914. Soon after WW I, there were more and more realizations, many under the control of Lewe or Marcus. Maillart seems to have been completely unknown in Germany, whereas some vague information must have existed on the activities of Loleit, either because he informally reported on this when attending the German "Betontag" before WW I, or by emigrated colleagues. CONCLUSIONS The three beginnings of mushroom ceiling construction presented in this paper can be compared in different ways. What is common to them all is that they each took place in countries without strict regulations in this special field, that could be interpreted as inviting freedom or challenges to the status quo. All three protagonists seem to have been of personal independence and energy - typical inventors, one might say. They were not bound by bureaucratic limits, but were eager to find a way of realizing their visions, in this case a way to reliably dimension and construct mushroom ceiling constructions. Their achievements were also affected by their role as engineers or responsible company owners or managers. What on the one hand enabled them to develop their ideas, on the other prevented them from publishing their invention, earning acclaim and a degree of fame. All three sooner or later

1805

faced great problems, or even catastrophes, due to legal or military war; envy and hate also spoiled personal achievements. On the scientific level, the different stories illustrate the how technological developments and theoretical solutions do not always progress together. The development of successful construction principles without being able to understand fully has often been a strong stimulus for theoretical developments and scientific progress. Looking back over the entire period, it seems strange how knowledge of, and respect for the pioneers of the mushroom slab have changed and depended on historical accident and the particular conditions. This should lead us to question more often whether we always give credit to those who most deserve it. This brief history can be read as a plea for the subordination of theoretical understanding to practical advantages, which in this case were very clear. The nature of invention is often that it comes in its own time; but it seems that the conditions which can enable a breakthrough can also prevent its success. More generally, increasing the level of technical development both demands and creates the means of its communication. However, transparency and a full exchange of knowledge are not always welcome or desired, whether for commercial reasons in capitalist, or ideological reasons in socialist-communist societies. Technology as an instrument of power becomes visible in the process of re-inventing or taking-over as a method of appropriation. The biographies of many Russian scientists and engineers reveal this situation. For a better future, the past had to be poor and stupid. Western or foreign technology is first seen as the source of modernization; then, in a second step, it becomes a competitor in the world-wide market. A final aspect of parallel invention, as exemplified by the mushroom slab, is the possibility of "chaotic" development – unconstrained developments in a variety of directions that allows choice and, sometimes, correction if forgotten ways are discovered to be the best in new sets of conditions. So, by researching, documenting and explaining the past, the historian of technology helps create a future resource. REFERENCES Billington, David P, 1997. Robert Maillart: builder, designer and artist, New York: Cambridge University Press. Fuerst, Armand; Marti, Peter, 1997. "Robert Maillart's Design Approach for Flat Slabs", Journal of Structural Engineering, vol 123, no. 8 (Aug. 1997) pp. 1102-10.

1806

Gasparini, Dario A, 2002: "Contributions of CAP Turner to Development of Reinforced Concrete Flat slabs 1905-1909", Journal of Structural Engineering, vol 128, no. 10 (Oct. 2002) pp. 1243-52. Lopatto, Aleksandr Eduardovich, 1969. Artur Ferdinandovich Loleit. K istorii otechestvennogo zhelezobetona (A.F. Loleit. The national history of reinforced concrete), Moscow: Literatura po stroitelstwo. Mayer, Max, 1912. "Die trägerlose Eisenbetondecke" (The beamless reinforced concrete slab), Deutsche Bauzeitung, Mitteilungen über Zement, Beton- und Eisenbetonbau, vol 46 (1912), no. 21, pp. 162-6; no. 22, pp. 174-5. Nashokina, Maria, 1999. Sto arkhitektorov moskowskogo moderna. Twortcheskie portreti (100 Architects of Moscow Modern. Work Portraits), Moscow: Giraf. Stadelmann, Werner, 2001. "Ein Schweizer Ingenieur und seine Bauten in Russland" (A Swiss engineer and his buildings in Russia), (Schweizer) Baublatt, vol 112 (2001), no. 69, pp. 30-5.

1807