Eastwood, Tedesko, and Reinforced Concrete
A long with the George Washington Bridge in New York and the Golden Gate Bridge in San Francisco, the most famous American public work of the 1930s was Hoover Dam, on the border between Nevada and Arizona.1 Made of a new material, modern concrete, the dam was the largest concrete structure in the world when it was finished in 1936. But Hoover Dam was not an example of efficient design. Built when materials and labor were cheap, the dam used far more concrete than it needed to be safe, and its massive look did not take advantage of concrete’s potential for elegant thinness.
During the first four decades of the twentieth century, the works of two civil engineers, John Eastwood and Anton Tedesko, realized the potential for elegance and economy in reinforced-concrete design. Eastwood and Tedesko stressed the idea of form over mass, the idea that the amount of mass needed in a structure could be reduced safely by the use of an efficient form. The civil engineering profession was at first suspicious of their approach. The kinds of structures involved, thin dams and roof shells, are today rarely built, although most of those already in use have served well with proper maintenance. Ultimately, the profession recognized the validity of what Eastwood and Tedesko accomplished. The idea of form over mass, and the related idea that efficiency, economy, and elegance must all be present in a good structural design, still speak powerfully to the needs of public works and private buildings today.
In the period from 1876 to 1939, the new networks of electric power and telephony, the processes of oil refining, and the making of machines such as the automobile came under the control of a small number of large business organizations. In the engineering of large-scale bridges and buildings, though, large private firms did not dominate. Bridge designers usually worked for public authorities as consultants or as staff engineers, while designers of buildings and other structures usually worked as consultants. Eastwood and Tedesko worked as consultants in private practice. Unlike the great names associated with machines and networks, innovators of new structures were not well known. But in their works, Eastwood and Tedesko exemplified the qualities that characterize outstanding technology.
Mass versus Form in Reinforced Concrete
Roman builders made concrete by mixing a natural cementing agent with water, sand, and crushed stones. During the nineteenth century, a new and better cement came into use, an industrially produced agent called Portland Cement, that made a stronger concrete. Embedding steel rods in the new concrete enabled it to resist higher tension and created a new building material, reinforced concrete. The materials used to make reinforced concrete are inexpensive and readily available in most parts of the world, so that building in the new material is now a major part of the construction industry.2
Concrete is custom-made at the building site for most projects and is therefore a less well-controlled material than manufactured steel. But once engineers could assure themselves that they could control the quality of the material during construction and see it perform safely in use, they began to design in reinforced concrete. At first, most engineers saw it only as a cheaper substitute for stone and used it to build heavy, stone-like structures for dams, bridges, and buildings. But a few engineers saw the potential for reinforced concrete to carry loads through new forms that were not practical in stone.
The first engineer to realize fully the possibilities of reinforced concrete was the Swiss structural engineer Robert Maillart (1872–1940). In 1930 he wrote: “It is usual to believe that massive structures are necessarily strong. Mighty pillars and thick arches arouse confidence in the mind of the observer, while light membered structures cause more anxiety than delight.” But, he added, “in antique remains firm slender columns are often found next to collapsed mass masonry” and “there is no doubt that slender structures are just as beautiful to the eyes of the layman and even more beautiful than massive forms.”3 In his bridges, Maillart progressively dispensed with mass in favor of lighter and more slender forms that controlled the way in which the structure carried load. In 1947 the New York Museum of Modern Art held an exhibition of his work, the first on the theme of structural engineering as art.4 The highlight of this exhibition was Maillart’s Salginatobel Bridge, the first reinforced-concrete bridge to become an International Historic Civil Engineering Landmark.5
John S. Eastwood and Anton Tedesko worked to achieve efficient, economical, and elegant structures of reinforced concrete in the United States. Eastwood devoted the latter part of his life to dams; Tedesko spent the first part of his career designing thin-shell roofs. Both stood for the idea of form over mass.
Eastwood and the Multiple Arch Dam
John S. Eastwood (1857–1924) was born on a farm near Minneapolis, attended the University of Minnesota without completing a degree, and then worked as a surveyor and construction engineer (figure 9.1). He settled in Fresno, California, in 1883. In 1895 he helped build a hydroelectric system for the San Joaquin Electric Company. During a drought in 1899, the company failed because it did not have a reservoir large enough to store water to power the electrical network. Eastwood realized that dam building could play a crucial role in the often arid American West.6
Most dams in the United States at that time were earth dams, consisting of an earth wall, sloped on each side, to block the flow of a stream (sidebar 9.1). Larger earth dams had a wall of rock, clay, or concrete in their core to prevent seepage. A second type of dam, called gravity dams by engineers, consisted of an exposed wall of rock or concrete, sloped outward mainly on the downstream side. A variant of the concrete gravity dam was the Ambursen “flat slab” dam, which saved concrete by making a relatively thin slab sloped on the upstream side with widely spaced perpendicular buttresses on the downstream side. A third major kind of dam was the arch dam, in which the structure’s shape provided most of its strength. An arch dam worked like an arch bridge laid on its side, with the outside of the arch resisting the water. An arch dam needed much less material than a gravity dam to hold back the same amount of water.7
At the turn of the century, wealthy investors saw the potential for California to grow if water and electric power could be supplied from mountains in the interior to cities along the coast. Dams were needed to store water for drinking and irrigation and for powering electric generators. In 1901 Henry Huntington, whose uncle was a founder of the Central Pacific Railroad, began a system of power stations and transmission lines to bring electricity to Los Angeles.8 In 1902 Eastwood proposed three dams to impound a reservoir in Big Creek, a tributary of the San Joaquin River, as part of this system.
Figure 9.1. John Eastwood. Courtesy of Michigan State University Archives and Historical Collections, East Lansing, MI.
Earth Dams
Gravity Dams
Arch Dams
Eastwood envisioned a new kind of dam, one that would employ multiple arches of reinforced concrete. For each dam at Big Creek, he designed several arched walls, each forty feet wide, with buttresses on the downstream side for support. The three dams would require 73,000 cubic yards of concrete, more than the 64,000 needed by core walls for earth dams. But the design did away with 1 million cubic yards of earth. A traditional concrete gravity design would have required about 300,000 cubic yards of concrete. Eastwood calculated that an arched concrete wall could hold back as much water as a far heavier flat wall of concrete. But Huntington and his engineers commissioned three concrete gravity dams at greater expense instead.9
While waiting for approval at Big Creek, Eastwood had the chance to build two arch dams in California. In 1908, to help a lumber company hold and transport logs, Eastwood built the Hume Lake Dam in the Fresno region, the first ever built to use multiple arches of reinforced concrete (sidebar 9.2 and figure 9.2). The dam cost $46,000, far less than the $70,000 estimated for a gravity design that would have used rockfill. The Hume Lake Dam was 667 feet long, 61 feet high at its highest point, and contained twelve arched walls, each 50 feet wide. The arches were sloped on the upstream side and supported on the downstream side by buttresses.10
In 1910 the Bear Valley Mutual Water Company commissioned Eastwood to build a dam to store water for irrigation in the San Bernardino region of southern California. His design showed the aesthetic as well as technical possibilities of using form rather than mass in reinforced concrete. Built in 1910–11, the Big Bear Dam was 363 feet long, 80 feet high, and had ten arches each spanning 32 feet. The buttresses were 18 inches thick at the top and widened to more than 5 feet at the foundations. Because of the greater height at Big Bear (compared with that at Hume Lake), Eastwood designed every buttress to be braced laterally by bridge-like arches and frames between the buttress walls. From a distance, this gave an elegant lattice-like appearance to the downstream side of the dam (figure 9.3).11
Eastwood soon found a chance to build a much larger dam using multiple arches. The Great Western Power Company wanted a hydroelectric power dam at Big Meadows, fifty miles north of Sacramento in northern California. Eastwood sent a proposal in early 1911 to H. H. Sinclair, the company vice president, for a multiple-arch design 720 feet long and 150 feet high with twenty-two arches, each 30 feet wide. Sinclair sent Eastwood’s proposal to James Schuyler, a leading authority in the West on dam design. Schuyler approved Eastwood’s design and noted that it would cost only about $600,000 compared with about $1.2 million for a gravity dam. Alfred Noble, an expert in New York, gave a similarly favorable review.12
Figure 9.2. Hume Lake Dam, near Fresno, California. Courtesy of the Prints and Photographs Division, Library of Congress, Washington, DC. HAER-CA-16-1, Historic American Engineering Record.
Figure 9.3. The Big Bear Dam. Courtesy of Professor Donald C. Jackson, Lafayette College.
Then disaster struck. Sinclair had to resign temporarily for health reasons, and the company president died. Although Sinclair returned, the new president called in John R. Freeman (1855–1933), a leading civil engineer and dam designer, for advice. Freeman believed that massive dams were the only ones that were safe. He also insultingly characterized Eastwood as a designer who “has become so impressed with the beauties of his multiple arch that I presume he will build his house shingled with semicircular tiles and ultimately have his hair trimmed in scallops.”13 At Freeman’s urging, work on Eastwood’s dam stopped in October 1912 after $188,500 had been spent on the concrete and $146,000 on excavation. In March 1913 the company abandoned the design and built a massive earth dam in its place.14
Eastwood rebounded, though, when he became a consultant to an open competition for the Mountain Dell Dam near Salt Lake City, Utah. The State of Utah asked Eastwood to submit a design for a multiple-arch dam and invited other designers to submit plans for a gravity dam and an Ambursen dam. Contractors then submitted bids estimating what they would charge to build each design in two stages, a “base” dam 110 feet high and a completed dam 150 feet high. Eastwood’s multiple-arch design won with bids of $75,300 for the base and $139,000 for the completed dam. The lowest bids for the gravity dam were $88,700 and $226,000 respectively, and for the Ambursen dam $117,000 and $217,000. The Mountain Dell competition proved that Eastwood’s ideas could triumph when given the chance in open competition with rival methods.15
Eastwood was able to build ten more dams before his death in 1924. The largest of these was the Lake Hodges Dam, begun in 1917 on the San Dieguito River north of San Diego.16 As the dam neared completion in March 1918, a flood sent water through the opening of an unbuilt arch. The heavily loaded structure suffered no damage, dispelling a worry that multiple-arch dams would fail if one of the arches failed or had not yet been built. In his Littlerock Dam in the Mojave Desert, finished in 1924, Eastwood carried his aesthetic vision further by proposing a radial design, in which the arches were arranged along a curved rather than straight line. Objections from state engineers led to the construction of a straight dam, still an elegant structure of Eastwood’s design.17 At Webber Creek, about fifty miles east of Sacramento, he designed a very thin 115-foot high dam with a central arch 140 feet wide and two arches 105 and 115 feet in span. The dam was built only up to 90 feet in height.18 In his later dams, Eastwood achieved a level of efficiency not equaled since in American dam design.
On March 12, 1928, the St. Francis Dam north of Los Angeles collapsed catastrophically, killing more than 400 people.19 Although this was a gravity dam built by the City of Los Angeles, its failure prompted the California legislature to pass a law placing all dams in the state under the supervising authority of the state engineer, who asked the engineer Walter Huber, a follower of John Freeman, to head a “multiple arch dam advising committee.” Huber’s committee arbitrarily decided that Eastwood’s Lake Hodges Dam was unsafe, and in 1936 engineers added concrete reinforcement into the openings between every other pair of buttresses. The reinforcement resembled the cross-bracing in the towers of the new Golden Gate Bridge in San Francisco, but its use in the dam was not the result of any evidence pointing to a need for it.20
During the 1930s California and other U.S. states built very narrow long-span suspension bridges following the deflection theory, even though the history of smaller nineteenth-century bridges of similar dimensions showed the susceptibility of such bridges to failure in wind.21 At the same time, new dams were built to be massive. A 1920 survey of one hundred dam failures showed that no thin arch dam had ever failed structurally; nearly all failures were of massive masonry or earth dams.22 Yet the engineering profession believed arch dams to be unsafe. The Tacoma Narrows collapse in 1940 showed the error in 1930s suspension bridge design, and time has vindicated the safety of Eastwood’s multiple-arch dams. Although a few have been rehabilitated, none has ever failed.
Anton Tedesko Comes to America
The idea of form over mass also developed in Europe in the pioneering design work of Dyckerhoff & Widmann, an engineering and construction firm in Wiesbaden, Germany. Working in reinforced concrete, the firm experimented with new ways to cover large spaces in the 1920s. The firm built domes and cylindrical “barrel” shells to serve as large roofs of extraordinary thinness.23 The possibilities of thin-shell design using reinforced concrete fascinated an Austrian civil engineering graduate, Anton Tedesko (1903–94), who joined the firm in 1930 after spending two years working in the United States (figure 9.4).24
In 1932 the German firm sent Tedesko to America to introduce thin-shell concrete roof construction there. The Chicago office of the Roberts and Schaefer Company agreed to give him office space. Over the next two years, Tedesko met with engineers, architects, builders, and owners in an effort to promote the new German thin-shells, under the name Z-D (Zeiss-Dywidag) Shell Roofs.25 But he faced the worst possible conditions in which to argue for new construction: the deep economic depression of the early 1930s and a conservative civil engineering profession. In mid-1932 Tedesko traveled to New Orleans to design a large arena in collaboration with a local architect and engineer. After long hours over a drafting board in the sticky delta summer, Tedesko produced a concrete shell design only to see it rejected in favor of a conventional steel truss roof.26 Like Eastwood at Big Creek, Tedesko’s first effort was beaten by a standard design: massive dams and steel trusses were typical American solutions that engineers preferred in the 1920s and 1930s to exotic-looking thin concrete arches and shells.
Tedesko met with success, however, at the Century of Progress World’s Fair in Chicago of 1933–34. He won a contract to design and build a thin-shell concrete roof for the Brook Hill Dairy Exhibit. On American farms, dairy cows were housed in wooden barns. Tedesko convinced Brook Hill’s architect and consulting engineers to accept the unorthodox idea of a pavilion in reinforced concrete. The engineers advertised the resulting structure as giving cows “comfort and safety greater than that ever before enjoyed by any cows anywhere” in a building that “cannot burn, rust, rot, or blow away.”27 The dairy structure had a barrel-shaped roof and tests of its load-carrying capacity impressed engineers from the the University of Illinois and the Portland Cement Association (the trade group of cement manufacturers in the United States), as well as representatives of the Roberts & Schaefer Company.28 The roof for cows did not cause the rush to shells that Tedesko had hoped to see. But Tedesko found new work and in 1934 he became an employee of Roberts & Schaefer, although the company that year reduced salaries by 45 percent.
The Hershey Arena
Tedesko’s breakthrough as a designer came later in 1934, when he designed the dome of the Hayden Planetarium in New York City (between 77th and 81st streets along Central Park West in Manhattan). This was the first reinforced-concrete thin-shell dome to be built in the United States; it was eighty feet and six inches in diameter and only three inches in thickness (figure 9.5).29 Tedesko made a convincing case for the economy and safety of the 1920s domes in Germany. He also benefited from worries that New York was falling behind other U.S. cities. Planetaria had been built in Philadelphia and Chicago, and one was under construction in Los Angeles. New York had no planetarium and was eager to have this new means of projecting the images of celestial bodies in motion.
Figure 9.4. Anton Tedesko in 1936. Courtesy of Princeton Maillart Archive, Princeton University, Princeton, NJ. Tedesko Papers.
Tedesko’s greatest opportunity came in 1935, though, when the Philadelphia representative of Roberts & Schaefer, James Gibson, introduced him to Milton Hershey (1857–1945), who owned the largest chocolate-making plant in the world. In 1903 Hershey had built the town of Hershey, Pennsylvania, around his factory, where he had also founded a school for orphans. The Depression hurt the chocolate industry and in 1935 Hershey decided to build a sports arena for ice hockey as a way to keep his workers employed.30 On January 21, 1936, Tedesko submitted a proposal to design and build a thin concrete shell to enclose the arena. The Hershey Company accepted with the provision that he employ chocolate workers to do the construction. Tedesko agreed.31 Work started immediately with design staff hired in Chicago, and on March 11 chocolate workers began to dig the foundations of the structure. The Hershey Arena would cover an area 340 feet long and 232 feet wide. For the oblong arena, Tedesko designed a thin reinforced-concrete, barrel-shell roof, three and one-half inches thick, supported across its width by eight arches. He did not design cross-ribs between the arches in the belief that they were unnecessary.32
Figure 9.5. The Hayden Planetarium. Courtesy of Princeton Maillart Archive, Princeton University, Princeton, NJ. Tedesko Papers.
A roof posed a challenge different from that of a bridge or dam. On a bridge, live load from traffic is significant, and a dam must resist the live load of water on its upstream face. On a long-span concrete roof, live load (mainly rain and snow) is a small fraction of the dead load of the structure itself. Tedesko realized that the supporting arches did not need to be of uniform depth. Half of the roof’s weight would fall on the abutments, and he designed the arches to be twelve feet deep at these points, where they merged into the side walls of the arena. The arches tapered to a depth of five feet at the crown, giving a graceful appearance as well as the means for stiffening the thin-shell roof. Although it was only three and one-half inches thick, the shell roof was strong enough to carry its own weight and the weight of any live load, even without the supporting arches. (sidebars 9.3 and 9.4).33
Tedesko designed the arches to be able to support the entire roof load, including the thin shell and all of the live load. He also made calculations to show that the thin shell could carry its own weight and live load without help from the arches, except near their lowest edges. It was thus a conservative design, but one which still showed the possibilities for supporting wide spans with relatively small amounts of material.
In addition to an efficient design of the structure, Tedesko had to develop a construction process that could result in reasonable economy. He designed a reusable wooden scaffolding that could support one unit of two arches with connecting thin shells. After the concrete had been cast and had hardened, the scaffolding was lowered and moved to an adjacent unit. Removing the wood required carefully lowering the supports beneath the arches in a pre-designed sequence that Tedesko controlled from a central station (figure 9.4). The concrete had to be stiff so that it could be cast on steeply sloped forms without flowing down (figure 9.6). The final result showed the thinness of shells and arches (figure 9.7), which would be partly concealed when the side walls of the arena were finished (figure 9.8).
The Hershey Arena was the largest thin-shell concrete roof in America, covering 78,880 square feet. It demonstrated that such a huge area could be covered by a concrete surface of extraordinary thinness, primarily by taking advantage of the curved shell form. For Tedesko this was “the most satisfying challenge of the 1930s. … The engineering and construction decisions were mine. No codes existed that would apply to this work. No rules had to be followed. I shaped and calculated the structure according to my best judgment, influenced by what I had learned in Wiesbaden.” The Hershey Arena gave Tedesko a unique chance to develop independent judgment and self-confidence. “In Europe, there would not have been only a single person in charge of such a project, and certainly not someone 32 years old.”34
Figure 9.6. Hershey chocolate workers casting concrete. Courtesy of Princeton Maillart Archive, Princeton University, Princeton, NJ. Tedesko Papers.
Figure 9.7. Hershey Arena arch, half cross section. Courtesy of Princeton Maillart Archive, Princeton University, Princeton, NJ. Tedesko Papers.
Figure 9.8. Completed Hershey Arena in use. Courtesy of Princeton Maillart Archive, Princeton University, Princeton, NJ. Tedesko Papers.
Tedesko faced a crisis on July 3, 1936, during the concrete casting for the first roof section of the Hershey Arena. As he would describe years later, “we started understaffed, had trouble with concrete aggregate, with breakage of form supports. My instructions that tarpaulins be available to cover fresh concrete were ignored. Concrete started to set prematurely under the hot sun; I added water, and the mix became too wet.” Then: “At 2:30 a.m. hell broke loose with an electric storm and torrential rain. The men dropped their tools and fled to covered areas.” What happened next was a concrete engineer’s worst nightmare. “Rivers came down the arched roof and washed down the concrete which had not yet hardened. Concrete mud slides came to rest on the flat side roofs, not strong enough to support them, and I assumed that the increasing load of the ponding water (perhaps 90 tons) would lead to collapse.” Tedesko worked frantically, first trying to siphon off the water but “finally breaking holes through the young concrete of the flat side roofs, through which gravel, concrete mud, and rain water could drop, relieving the dangerous load. … I was dirty and wet, but I felt good, like a conqueror. I could also see the humor of the situation.”35
The Hershey people saw no humor, though, and were sure that the structure would have to be torn down and a standard steel truss roof built instead. But Tedesko confidently promised to make all right. After seventy-two hours of round-the-clock work to clean up the mess, Tedesko was ready to begin the concrete placement again. This time all went well and soon word spread around the county that something unusual was arising in the green rolling hills of the Susquehanna Valley. Visitors came, especially prominent engineers and builders, some of whom would become close friends of Tedesko and help him get future projects. One was Lieutenant-Commander Ben Moreell, who later became a full admiral and an aide to President Roosevelt during the Second World War. Moreell and other officers saw Tedesko’s long-span roof as an ideal form for military aircraft hangars. Much of the housing for U.S. warplanes during World War II thus owed their design to Tedesko’s chocolate arena.36
On one of his numerous train trips between Harrisburg and Chicago, Tedesko noticed everyone looking at him as he sat on the aisle in the dining car. Suddenly he realized that the woman across the aisle was the First Lady, Eleanor Roosevelt.37 Such were the rewards of his hectic schedule during the last half of 1936.
Tedesko still kept in touch with his colleagues in Germany, but a trip to Europe in late 1937 persuaded him that Nazi Germany was no place to live. He became a U.S. citizen in 1938 and married an American, Sally Murray, whom he had met in Chicago three years earlier.38 Americans began to accept thin-shell roofs after the Hershey Arena, and in 1937–38 he began a new series of roof projects as the designer. Three of these characterize Tedesko’s mastery of diverse forms in American conditions. The first was an arched Hershey-like roof shell for the Philadelphia Skating Club and Humane Society in Ardmore, Pennsylvania. Charles Schwertner, who had helped Tedesko on the site at Hershey, became the building contractor for Ardmore and insured a well-built shell with arches spanning 116 feet in a building 235 feet long. It was, according to Tedesko, “the best-looking shell structure of the 1930’s … attained through joint efforts with architect Nelson Edwards and contractor Schwertner.”39
Tedesko worked under another Austrian at Roberts & Schaefer, John Kalinka, who in 1937 hired a third Austrian engineer, Eric Molke, to fill in for Tedesko while the latter was in Europe. Molke worked with Tedesko on two dome roofs covering trickling filters for a water treatment facility in Hibbing, Minnesota.40 These concrete domes were an unusual choice. Trickling filters are usually open but had to be enclosed at Hibbing because of the dangers of icing and heavy snows common in northern Minnesota. The designers made an elliptical (flattened) dome with a ground-plan diameter of 150 feet and a height at midspan of 32 feet. A flat dome shape had the structural advantage of being vertical at the base and thus not requiring a base-reinforcing ring, essential with a spherical dome that would push outward as well as down. The design avoided the more complex mathematical analysis needed for the dome-ring connection.
Barrel roofs are more common than domes because the former can cover rectangular buildings. The largest of the early barrel shells by Tedesko was a roof at Natchez, Mississippi, for an Armstrong tire factory covering 121,600 square feet. Comparative studies of more standard structural types showed that the concrete roof was competitive and reduced the danger of fire. Tedesko had known the local architect through his Chicago fiancée. The main structure was made of cylindrical shells forty feet wide and fifty feet in span. Tedesko calculated the maximum compressive stresses in the shells to be less than 10 percent of the compression capacity of the concrete. Typical for most shells, these results illustrated that thinness did not compromise safety.41
By 1939, with these and a number of other contracts in various stages of development, Tedesko had succeeded in proving the value of a new type of roof for large buildings in the United States, using thin reinforced concrete instead of just steel. Tedesko would only reach international fame years later, most notably for his work as structural designer of the Vertical Assembly Building and other structures for the U.S. space program at Cape Canaveral in Florida. Unlike the better-known German rocket engineers who came to the United States after World War II, Tedesko brought his knowledge of German engineering to America before the war. Like Maillart in Switzerland, Tedesko stood for an ideal that did not dominate the design of public structures built in either Germany or the United States in the 1930s: the ideal of form and lightness rather than mass.
