On the evening of July 17, 1981, between fifteen hundred and two thousand people filled the atrium of the Hyatt Regency Hotel in Kansas City, Missouri, for a Friday dance contest. Two walkways hung above the crowd from the atrium's roof framing, one at the second floor and one at the fourth. At 7:05 p.m., as the band came back from its break, both walkways gave way at once. The upper span fell onto the lower, and both crashed into the atrium floor. At least 114 people died and more than 200 were injured, in what a federal investigation would call the deadliest structural collapse in the country's history.
The National Bureau of Standards, called in by the mayor days later, found a connection that had never been shown to work. Each walkway's steel box beams hung on rods that bore directly against the beams' flanges, with no stiffener or plate to spread the load, a detail so far outside normal practice that it appears nowhere in the American Institute of Steel Construction's own connection tables. Run through the numbers the building code required, even the connection as originally designed could carry only about sixty percent of the load it needed to.
It never had to carry that much. The original drawings ran a single rod continuously from the roof, past the fourth-floor beam, down to the second-floor beam, so the fourth-floor connection bore only its own walkway's weight. In February 1979 the steel fabricator, Havens Steel Company, proposed an easier version to build: a two-rod system that made the second-floor walkway hang from the fourth-floor walkway instead of from the roof directly, doubling the load the fourth-floor connection had to carry. G.C.E. International received the revised drawing as one of forty-two shop drawings submitted on February 16 and mailed all of them back marked approved ten days later. Daniel Duncan, the engineer in day-to-day charge of the design, later admitted he had not done what would have been necessary to confirm the connection could still hold.
The hotel had already been warned once. In October 1979, part of the same atrium's roof collapsed during construction, and Duncan's firm promised the owner a full check of every member holding it up. The disciplinary case that followed the 1981 collapse found that check, too, had never reached the connection that mattered. The hotel opened in July 1980 with the fourth-floor connection already down to thirty-one percent of the capacity the code demanded, a margin so thin that the federal investigators' own upper-bound estimate of the crowd on both walkways when they fell, sixty-three people watching a dance contest below, was enough to bring them down.
In 1984, on a complaint from the state board that licenses engineers, Missouri's Administrative Hearing Commission opened proceedings against Duncan, Gillum, and their firm. After a twenty-seven-day hearing, the Commission found all three grossly negligent, and the board followed by revoking Duncan's and Gillum's licenses and G.C.E.'s certificate of authority to practice as a firm. A stamp is meant to certify that somebody ran the numbers. On the Hyatt Regency's fourth floor, it certified only that somebody had read the page.