Century 21 World's Fair
Nov 27, 2023
The Seattle World's Fair of 1962 celebrated Century 21, offering a vision of the future to 10 million visitors and defining Seattle as a city of innovation. Structural engineers contributed to this vision through the application of pioneering techniques in the design of the fair's structures -- the Space Needle, the Washington State Coliseum, the Monorail, the United States Science Pavilion (now Pacific Science Center), and other permanent and temporary structures. Their design and construction involved cutting-edge structural technology, challenging the fair's designers to push the limits of contemporary structural design. The structures incorporated tension-cable roofs, pre-cast concrete, high-rise steel, thin-shell concrete -- all relatively new methods of building, offering new possibilities to the fair's future-thinking design. By design, the buildings and structures expressed and supported the fair's celebrations, while also creating a landmark urban center with an enduring role in the life of the city.
Structures of the Fair
Structural engineers collaborated with the architects in incorporating innovative concepts into the fair’s distinctive buildings. Their efforts impressed both fairgoers and armchair travelers who read about these achievements in popular and professional publications. Harlan Edwards (1893-1975), Progress Engineer for the Century 21 Exposition, summarized these accomplishments in his introduction to Concrete Construction for the Century 21 Exposition, proceedings of the American Concrete Institute’s 15th Fall Convention held in Seattle on September 28 and 29, 1962. He emphasized the speed and economy of the building process as well as the beauty of simple lines, and the efficacy of structures free of interior supports:
"Here, in architecture as in people, beauty is characterized by simple, pleasing lines not embellished by costly ‘gingerbread.’ Witness the immediate popular acclaim of the Space Needle featuring the age-old graceful and simple sheaf, with a wide-brimmed hat above. Consider the Science Pavilion, a masterpiece of concrete design, technology and construction, termed by many fairgoers as ‘America's Taj Mahal.’
"Or the immense Coliseum with its massive structural frame and its unique roof suspension, or the delicate flower-like thin-shell structures, the straightforward Exhibition Hall with its long-span folded plate concrete roof, and the pre-stressed concrete parking structure that was not only built quickly, but provides effective service at a cost one-third less than usual.
"All these vividly illustrate our modern know-how, detailed further by those who did it" ("Concrete Construction for the Century 21 Exposition").
The Space Needle
The John Graham Company developed and designed the Space Needle, with architects John Ridley (b. 1913) and Victor Steinbrueck (1911-1985) and with structural engineering services provided by the Pasadena-based firm of John K. Minasian (1913-2007) and by Harvey H. Dodd & Associates, Seattle. Minasian had designed the structure for the Saturn rocket assembly gantry for NASA, establishing his knowledge of tower design. Gary Noble Curtis (b. 1913) worked with the Minasian firm at that time, and recalls the intensity of the 13-month schedule for its design and construction:
Describing the challenges of preparing an adequate foundation for the towering Needle, Curtis notes: "They had to start digging a hole. It was on glacially compacted silt, the soil was like rock. We had a limited site like 150 feet square. So we clipped off the corners and made a Y-shape, and went down like 30 feet, and a 12-foot thick pad at the bottom, figured out the mass of this thing and what the overturning would be ... it’s pretty awesome ..." (Structural Engineers Foundation of Washington).
It took 467 cement trucks less than 12 hours to fill the foundation hole, which was 30 feet deep and 120 feet across, "the largest continuous concrete pour ever attempted in the West" (www.spaceneedle.com). The weight of the foundation is 5,850 tons, including 250 tons of rebar. The structure weighed 3,700 tons, with the center of gravity falling five feet above ground. It is bolted to the foundation with 72 30-foot-long bolts. The iconic structure sways one inch for every 10 mph of wind, and was build to withstand a wind velocity of 200 miles per hour. This doubled the 1962 building code specifications.
According to the construction firm, Howard S. Wright Construction Co., its earthquake resistance is twice that required by code, and its wind resistance allows it to tolerate gales over 150 miles per hour. Curtis said, "I’ve heard comments that there is a million more dollars of steel in the Needle than there needed to be, very well could have been. However, if the tower wasn’t done when the Fair opened, a million dollars (of a total construction cost of $4.5 million) was nothing" (Structural Engineers Foundation of Washington).
At the time of its construction, the Space Needle ranked as the tallest structure west of the Mississippi, at 605 feet -- edging out Seattle’s Smith Tower. On the occasion of its 37th birthday, April 21, 1999, Seattle's Landmarks Preservation Board named it an official City of Seattle Landmark. In its Report on Designation, the Landmarks Preservation Board wrote, ‘The Space Needle marks a point in history of the City of Seattle and represents American aspirations towards technological prowess. [It] embodies in its form and construction the era's belief in commerce, technology and progress’" (www.spaceneedle.com).
Washington State Coliseum Engineer Peter H. Hostmark (d. 1969) worked with the fair's principal architect, Paul Thiry (1904-1993), in designing a 130,000-square-foot pavilion as a large clear span which housed exhibits including the World of Tomorrow accessed by a 28-foot ride on the Bubbleator. Thomas Kane, with Andersen Bjornstad Kane, served as a special advisor to contractor Howard S. Wright during the construction of the Coliseum, assisting with tensioning, ring beams, and cables. As Kane recalls, "Thiry’s concept was putting a tent over the whole fairgrounds ... The Expo commission cut him down to size" (Structural Engineers Foundation of Washington). The Official Guide Book to the Seattle World's Fair described the building's form: "In the shape of a hyperbolic paraboloid, it has no interior roof supports. Four massive concrete abutments support the building's roof, which is 110 feet or 11 stories high. The aluminum paneled roof is supported by steel compression trusses and nearly 6 miles of steel tension cables. It cost $4.5 million to build, and was paid for by the State of Washington, Department of Commerce and Economic Development" (Guide to the Fair, pp. 26-27). Thomas Kane said of the cable-suspended roof that it was "pretty unique at that time. There were very few structures using cable as the main roof suspension system. And there was very little in the code" (Structural Engineers Foundation of Washington). More recently there have been structural issues that have led to leaking, such as at the 1986 NBA game that was "rained out" -- the first-ever National Basketball Association rainout. Kane had this story:
According to B. Richal Smith (b. 1932), a Hostmark employee from 1961 to 1963, the Hostmark firm did the structural engineering on all the fair buildings designed by Paul Thiry, in the Coliseum vicinity (Smith conversation). These would include the International Commerce and Industry Buildings (now known as the Northwest Rooms) and the Sweden Pavilion (later the Northwest Craft Center).
The Seattle Monorail
One of the most notable structures built for the fair was the Seattle Monorail, the train that ran back and forth above the street from the fairgrounds to downtown Seattle at Westlake. Johann Enderlein, a structural engineer with Alweg Rapid Transit Systems of Washington State, offered this prediction in 1962:
For the nation’s first full-scale commercial monorail system, the Alweg Rapid Transit Company designed the Monorail cars and built them in Germany, then shipped them from Bremen to New York for cross-country train shipment to Seattle. Engineer Einar Svensson worked with Alweg, and later relocated to the greater Seattle area with his Urbanaut firm, specializing in monorail design. The Washington structural engineering firm Anderson Birkeland Anderson (ABA, later BergerABAM) collaborated in the design of the concrete monorail beams, manufactured in Tacoma. Svensson observed that the train and the beam it rode on were two integral parts of the Alweg monorail. You couldn't separate them, and since the train was manufactured in Germany and the beam here, the beam had to be constructed to precisely fit the train.
According to Robert Mast, an early ABA employee and partner, the Howard S. Wright contract for the monorail was a design/build contract. Concrete Technology was a subcontractor to Howard S. Wright, and ABA was a subcontractor to Concrete Technology. Two brothers, Arthur Anderson (1910-1995) and Thomas Anderson (1912-2000) had two companies: one was ABA, which was the engineering company; the other was Concrete Technology, which was the fabricator of pre-stressed concrete beams. Svensson recalled, "I went down there [to Concrete Technology, in Tacoma] for an inspection in the plant, and they had me meet two cement workers. They had overalls on and big boots. I said, ‘I’m supposed to meet Dr. and Engineer Arthur and Thomas Anderson.’ They both stretched their hands out" (Structural Engineers Foundation of Washington).
Mast relates that Alweg's original design for the monorail's beam bearings used machine bronze, which were expensive and required tight tolerances. ABA developed an alternative using laminated pads and stainless steel. This was done working with bearings specialist E. Terry Dalton, of Lake Oswego, Oregon. Mast says, "I believe that was a new concept in 1960-61" (Structural Engineers Foundation of Washington). "At that time," notes Einar Svensson, "the Germans and French were far ahead [of the U.S.] in concrete technology, and … German codes were far more advanced. … I would say the codes were revised after this" (Structural Engineers Foundation of Washington).
The Monorail route required extensive curving and elevation changes of the beams. Every curve was unique. "It not like toy train track," said Mast, "where you have straight sections and curved sections. … Many of the beams might be half transition, half curved …. There were many people who said you could not pre-stress a curved beam. Some people said the tendons will try to straighten out and so the beam will try to straighten out; other people say the opposite: that the force of the tendons will make it bend more. But it turns out the tensile forces in the steel and the compressive forces in the concrete balance each other. And the design of the curved beams was almost the same as for a straight beam -- except for the torsion" (Structural Engineers Foundation of Washington). Arthur Anderson details monorail design and construction in his article, “Pre-Stressed Concrete Girder Production for Seattle’s Monorail:
"Two girder types were produced -- straight sections, 82 in number; and curved sections, 60 in number. The straight girders had a maximum span of 90 feet, and an average span 85 feet. The longest girder weighs approximately 60 tons. The straight girder section … is pre-stressed by a combination of pre-tensioned straight tendons and post-tensioned draped tendons. All tendons consist of seven-wire stress-relieved strand with a tensile strength of 250,000 psi. … "All curved girders had solid ends, and the hollow box sections were formed by plywood cores which remain in the girders. The plywood cores were rigidly held by the reinforcing steel cage which was prefabricated and welded as a complete assembly" (Concrete Construction for the Century 21 Exposition).
Construction of the Monorail system and stations took place over a 10-month period, at a cost of $3.5 million. The Monorail opened to the public on March 24, 1962. United States Science Pavilion (Pacific Science Center)
Architect Minoru Yamasaki (1912-1986), working in collaboration with Naramore, Bain, Brady & Johanson (later NBBJ) of Seattle, designed the complex of buildings originally known as the United States Science Pavilion, with structural engineering services provided by the Seattle firm of Worthington, Skilling, Helle & Jackson. John Skilling (1921-1998) and John V. "Jack" Christiansen (1927-2017) joined others on the Pavilion design team. Norman G. Jacobson Jr. (1927-2015) and his firm did the form work. The buildings were constructed for the federal General Services Administration and they housed the government's science exhibit as well as the Boeing Spaceareum.
Much of the work took advantage of a relatively new technique for handling concrete -- pre-stressed concrete, which had emerged in structural engineering in the 1950s. Concrete by itself is strong in compression (when pressed down upon) and weak in tension (when pulled apart). Pre-stressed concrete is concrete within which reinforcing steel bars (rebar) are stretched and anchored in order to increase the concrete's resistance to stress. Jack Christiansen called pre-stressed concrete "a wonderful technique that overcomes many of the drawbacks that come with concrete construction ... I had developed a great interest in thin shell concrete ... The whole thing is pre-stressed pre-cast concrete ... It’s a hexagonal shape, hyperbolic paraboloid shells, those are probably one and a half inches thick" (Structural Engineers Foundation of Washington).
John L. Hutsell, with Associated Sand & Gravel, explained (in 1962) "This exhibit complex is, in actuality, an interconnecting group of six different buildings all constructed of decorative precast, pre-stressed concrete and erected upon cast-on-site footings and substructures. The decision to utilize precast concrete was based upon several requirements: first, the time limits for construction nearly precluded conventional methods; secondly, the quality and beauty desired and the extremely critical design of the long, thin-shell wall sections made the degree of control that can only be achieved in plant work a necessity" ("Concrete Construction for the Century 21 Exposition").
As engineer John Skilling was reviewing the project drawings with architects Minoru Yamasaki and Naramore, Bain, Brady, and Johanson, he noted that the columns supporting the Pavilion’s geometric domes seemed "a bit chunky." He said, "I can make those columns thinner"("Skilling, John B. (1921-1998)"). And so he did. Christiansen later recalled an exchange with architect Yamasaki about the design of the Pavilion’s signature arches:
"I was working on the job and he came to the office and I was sitting there working on the towers … and that latticework at the top. And I looked at the latticework and I said ‘we don’t need all these members.’ So I was drawing it up, taking out the members that we didn’t really need. He walked down the aisle, and he stopped and he said ‘that’s not right … put all that back in.’ So I put it back in" (Structural Engineers Foundation of Washington).
The contract for the precast panels went to Associated Sand and Gravel. It was worth over a million dollars, the larger precast contract up to that time. The firm cast 500 panels for the Science Pavilion in just over five months. Christiansen noted that if you look at the buildings today, "they are in remarkably good condition. Keep in mind they are very thin sections -- three inches thick. And you’d be hard pressed to find a crack in there" (Structural Engineers Foundation of Washington). Seattle Center Complex
The Seattle Center Complex comprises the Exhibition Hall, Playhouse (later Intiman Theatre), and the Mercer Street parking garage. The Seattle-based firm of Kirk, Wallace, McKinley & Associates provided architectural services for this complex of exposition buildings along and spanning Mercer Street. The structural engineering firm of Worthington, Skilling, Helle and Jackson provided services for the Exhibition Hall and Playhouse, and Norman G. Jacobson & Associates, Structural Engineers for the Parking Garage.
The Exhibition Hall included a folded plate retaining wall along Mercer Street. "It's flower-like," Jack Christiansen said. "My design just came out of the mathematics of the shape" (Structural Engineers Foundation of Washington). Norman Jacobson detailed the design and construction: "Cost of the garage, including professional fees, taxes, supervision and inspection, two elevators, a 150-foot pedestrian overpass, automatic gates, ultra-sonic vehicle counters, landscaping, intercommunication equipment, washdown lines and exterior signs, etc., amounts to approximately $1,650,000, which breaks down to $3.46 per square foot, or $1,095 per car" ("Concrete Construction for the Century 21 Exposition"). Jacobson presented “Seattle Center Self-Parking Facility” at the 15th Fall Convention of the American Concrete Institute held in Seattle on September 28-29, 1962.
Opera House (McCaw Hall) Architect James J. Chiarelli (1909-1990), in consultation with architect/theater designer B. Marcus Priteca (1889-1971), oversaw the gutting of the Civic Auditorium and Ice Arena and the design in its place of the Opera House with its modern brick façade. The firm of Worthington, Skilling, Helle and Jackson performed the structural engineering for this project.
Christiansen wrote in 1962: "The conversion of the old Seattle Civic Auditorium into a modern 3,100-seat Concert Convention Hall and Opera House involved considerable structural work. The stage was deepened 28 feet and the existing gridiron was raised and enlarged. The existing 200’ span trusses were modified and the bottom chords were raised 10 feet. The main floor was changed to a parabolic bowl by the addition of dwarf walls and a light-weight concrete slab. Two parabolic balconies were added with the upper balcony carried by a 110' span, post-tensioned concrete girder. The exterior of the building was enclosed by a 60' high brick wall" ("Concrete Construction of the Century 21 Exposition").
Lester "Les" Robertson (1926-2021) worked with the firm on the design of the Opera House (as well as the Science Pavilion). He recalled, "I worked closely with B. Marcus Priteca ... . Benny had converted many of the old vaudeville theaters to movie houses. For Seattle, on the basis that the access to the fly gallery was too dangerous, he wanted to put an elevator up to the loft. Over a wager, I climbed the shear concrete wall to the fly gallery ... and he gave up on the elevator" (Hall of Fame). (Note: the fly gallery is a raised platform to the side of the stage that holds ropes and pulleys and other equipment for moving props and scenery. A stagehand stationed on the fly gallery works the ropes.)
Home of Living Light
This was a home constructed of plywood, a project commissioned by the Douglas Fir Plywood Association to demonstrate the possibilities of new plywood products. Plywood consists of thin sheets of wood glued together with the grain of alternating sheets running in opposite directions. Seattle Times reporter Alice Staples described a tour through the Home of Living Light as "a trip into the future" ("Future Seen in Plywood Home").
The house, designed to let in lots of light but also to enable the control of both light and air, consisted of a series of circles -- circular rooms surrounding an atrium entry court complete with pool and garden. The rooms could be accessed via the entry court and each had its own patio with an exterior entryway. This house of the future broke tradition with the square, and was planned to "eliminate today's conventional stud wall-framing, and permits the curves themselves to carry the roof load" ("Future Seen in Plywood Home"). Incidentally, the furnished home included bedding and dressing gowns made of paper-plus-nylon, designed to be disposable and thus eliminating the chore of laundry. (The exposition took place before the future in which sustainability became an issue.)
The Home of Living Light was a temporary structure. The architect was Alan Liddle (1922-2009) of Liddle and Jones, Tacoma. Engineer Fred Pneuman, with the Douglas Fir Plywood Association, worked on it. The lighting design was done by architect Edmund J. Schrang and consultant Kaye Leighton.
At the time, engineered wood products had begun to replace traditional wood materials. As Pneuman remembers it, “Everything in there was plywood. … It was designed to get light in. I think there was one six-foot straight wall. A lot of people came through that place. … It turned into a restaurant in Olympia … burned down in 1967.” Pavilion of Electric Power/Hydro-Electric Utilities Exhibit The Pavilion of Electric Power, a temporary structure designed by engineer Harvey H. Johnson (1915-2012), featured a spiral-shaped viewing platform overlooking a 40-foot-tall shell that simulated a dam. Three thousand gallons of water per minute flowed over the spillway into a large pond at the base.
The pond featured a map that pinpointed the location of dams in Washington state. People enjoyed throwing coins into the pool, and one attendant, Jack McCarthy, said, "But I wish they'd throw straighter. They're hitting the Washington map with four-bit pieces and knocking out the neon tubes" (The Seattle Times, April 29, 1962). The Aquadrome
The Aquadrome was a circular water course, a concrete tank that traced the outer rim of the stadium floor. It was four feet deep, 26 feet wide, and went 330 feet around. The tank contained 700,000 gallons of water and the structure provided two bridges so that persons and animals could get across this indoor moat to the center of the stadium. An anticipatory article in The Seattle Times noted that the Aquadrome would feature "high-speed water skiing, ski-jumps from floating platforms, gymnastics, human pyramids, barefoot water skiing, and costumed production numbers" (Stanton H. Patty). There were two shows a day.
The firm of Andersen Bjornstad Kane designed the Aquadrome circular water ski exhibit and the Howard S. Wright Construction Co. built it. Trygve Bjornstad (1913-2000) told friends that "the hardest part was getting the damned elephants onto the center island" -- a circus performance area (Hall of Fame). His design incorporated a special bridge for the reluctant animals.
A Structural Failure: the East Gate
On February 26, 1962, at 2:10 in the afternoon, the World's Fair's recently completed East Gate collapsed. This was a 60-foot-high, five-ply laminated-wood structure. “The ... structure had been standing free of its scaffolding since Thursday, said Dale Yount, foreman. Three men [carpenters cleaning out debris under the structure] had been standing under the entrance when it collapsed, but saw it weaving and rushed out of the way" ("World's Fair East Gate Collapses").
Architect Fred Bassetti (1917-2013) recollected his work on this structure with engineer Christiansen of Worthington, Skilling, Helle and Jackson: "At the time of its construction, my office looked out over this structure, and I kept an eye on it. On Monday morning I walked over and looked out the window, and it was all on the ground, a broken bird. It had three beams crossing diagonally -- a parabolic arch. There had been only a mild wind that weekend. I called Jack [Christiansen] and he and I went over to take a look. We’d had ongoing conversations with the contractor about screws vs. staples vs. glue. The contractor said staples would do the job ten times as fast as wood screws, but you’d better use twice as many staples. They also tested the glue, but they didn’t test the combination of glue and staples. It turned out that the staples didn’t hold the three layers together beyond about 5 percent of the surface, so the glue didn’t hold. The engineer and the contractor and the owner settled up the $150,000 in damages" (Bassetti conversation).
Publications about the Structures
There were several notable publications that praised and discussed the structures at the fair. The American Concrete Institute's publication of proceedings from its 1962 Fall Meeting held September 28-29 in Seattle, titled Concrete Construction for the Century 21 Exposition, included "Casting Curved Prestressed Monorail Beam," by Arthur Anderson, "Prestressing the Coliseum Ring Girder" by Peter H. Hostmark, "Seattle Center Self-Parking Facility" by Norman G. Jacobson Jr., and "Post-tensioned Folded Plate Roofs" by Jack Christiansen.
Civil Engineering magazine's February 1962 edition featured "Seattle's New Kind of World's Fair," by Harlan Edwards. Modern Steel Construction's January 1962 edition featured a cover shot of the Space Needle and "Step into the Next Century: For a Big Problem of Man in the Space Age, Structural Steel Provides Down-to -Earth Answers."
A Heritage of Structural Innovation Individually and cumulatively, the structures of the Century 21 Seattle World's Fair offered visitors a vision of the future and the impression that design technology as advanced by architects and engineers can drive transformations in human behavior and aspirations.
During the 50th anniversary of the exposition, the Structural Engineers Foundation of Washington assembled nine structural engineers who had taken part in the design of fair buildings and had observed the design, construction, and operation of these structures. The foundation recorded the recollections and observations of Richard Chauner (b. 1929), Jack Christiansen, Gary Noble Curtis (b. 1937), Victor O. Gray (1926-2016), Norman Jacobson, Thomas Kane (1927-2012), Robert Mast (b. 1934), Fred Pneuman (b. 1931), and Einar Svensson (b. 1926). The documentary film made of their reminiscences, titled Structural Engineers of the Seattle 1962 World’s Fair (May 2012 recording, May 2013 release) help preserve a record of the visionary ideas and technology introduced at the fair.
The Seattle Center's 50th anniversary observances of the Century 21 Exposition in 2012 reasserted these possibilities, yet to unfold for future generations.Structures of the FairThe Space Needle Washington State ColiseumThe Seattle MonorailUnited States Science Pavilion(Pacific Science Center) Seattle Center Complex Opera House(McCaw Hall)Home of Living Light Pavilion of Electric Power/Hydro-Electric Utilities ExhibitThe Aquadrome A Structural Failure: the East GatePublications about the StructuresA Heritage of Structural Innovation