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Hyatt Regency walkway collapse
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The Hyatt Regency hotel walkway collapse was a major disaster that occurred on July 17, 1981 in Kansas City, Missouri, United States, killing 114 people and injuring more than 200 others during a tea dance. At the time it was the deadliest structural collapse in U.S.
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The Hyatt Regency hotel walkway collapse was a major disaster that occurred on July 17, 1981 in Kansas City, Missouri, United States, killing 114 people and injuring more than 200 others during a tea dance. At the time it was the deadliest structural collapse in U.S. history.
Background
Construction on the 40-story Hyatt Regency Crown Center began in 1978, and the hotel opened in July 1, 1980 after construction delays including an incident on October 14, 1979, when of the atrium roof collapsed because one of the roof connections on the north end of the atrium failed.
The building was part of a master plan devised by Edward Larrabee Barnes and specifically designed by the newly created architect firm PBNDML. It was Missouri's tallest building.
The collapse was the second major structural failure in Kansas City in a little more than two years. On June 4, 1979, the roof of the then-empty Kemper Arena in Kansas City had collapsed without loss of life. The architects and engineering firms at the two collapses were different.
One of the defining features of the hotel was its lobby, which featured a multistory atrium crossed by suspended concrete walkways on the second, third, and fourth levels, with the fourth level walkway directly above the second level walkway.
Disaster
On July 17, 1981, approximately 2,000 people had gathered in the atrium to participate in and watch a dance contest. Dozens stood on the walkways. At 7:05 PM, the walkways on the second, third, and fourth floor were packed with visitors as they watched over the active lobby, which was also full of people. The fourth floor bridge was suspended directly over the second floor bridge, with the third floor walkway set off to the side several meters away from the other two. Construction issues led to a subtle but flawed design change that doubled the load on the connection between the fourth floor walkway support beams and the tie rods carrying the weight of the second floor walkway. This new design could barely handle the dead load weight of the structure itself, much less the weight of the spectators standing on it. The connection failed and both walkways crashed one on top of the other and then into the lobby below, killing 114 people and injuring more than 200 others.
Investigation
Three days after the disaster, Wayne Lischka, a structural engineer hired by The Kansas City Star newspaper, discovered a significant change in the design of the walkways. Coverage of the event later earned the Star and its sister publication the Kansas City Times a Pulitzer Prize for local news reporting in 1982.
The two walkways were suspended from a set of steel tie rods, with the second floor walkway hanging directly underneath the fourth floor walkway. The walkway platform was supported on 3 cross-beams suspended by steel rods retained by nuts. The cross-beams were box beams made from C-channels welded toe-to-toe. The original design by Jack D. Gillum and Associates called for three pairs of rods running from the second floor all the way to the ceiling. Investigators eventually determined that this design supported only 60 percent of the minimum load required by Kansas City building codes.
Havens Steel Company, the contractor responsible for manufacturing the rods, objected to the original plan of Jack D. Gillum and Associates, since it required the whole of the rod below the fourth floor to be threaded in order to screw on the nuts to hold the fourth floor walkway in place. These threads would probably have been damaged beyond use as the structure for the fourth floor was hoisted into position. Havens therefore proposed an alternate plan in which two separate sets of tie rods would be used: one connecting the fourth floor walkway to the ceiling, and the other connecting the second floor walkway to the fourth floor walkway.
This design change would prove fatal. In the original design, the beams of the fourth floor walkway had to support only the weight of the fourth floor walkway itself, with the weight of the second floor walkway supported completely by the rods. In the revised design, however, the fourth floor beams were required to support both the fourth floor walkway and the second floor walkway hanging from it. With the load on the fourth-floor beams doubled, Havens' proposed design could bear only 30 percent of the mandated minimum load.
The serious flaws of the revised design were further compounded by the fact that both designs placed the bolts directly in a welded joint between two facing C-channels, the weakest structural point in the box beams. Photographs of the wreckage show excessive deformations of the cross-section. In the failure the box beams split at the weld and the nut supporting them slipped through.
Investigators concluded that the basic problem was a lack of proper communication between Jack D. Gillum and Associates and Havens Steel. In particular, the drawings prepared by Jack D. Gillum and Associates were only preliminary sketches but were interpreted by Havens as finalized drawings. Jack D. Gillum and Associates failed to review the initial design thoroughly, and accepted Havens' proposed plan without performing basic calculations that would have revealed its serious intrinsic flaws — in particular, the doubling of the load on the fourth-floor beams.
Aftermath
The Missouri Board of Architects, Professional Engineers, and Land Surveyors convicted the engineers employed by Jack D. Gillum and Associates who had signed off on the final drawings of gross negligence, misconduct, and unprofessional conduct in the practice of engineering; they all lost their engineering licenses in the states of Missouri and Texas and their membership to ASCE. While Jack D. Gillum and Associates itself was cleared of criminal negligence, it was stripped of its license to be an engineering firm.
At least $140 million was awarded to victims and their families in both judgments and settlements in subsequent civil lawsuits; a large amount of this money came from Crown Center Corporation, a wholly owned subsidiary of Hallmark Cards which was the owner of the actual hotel franchise (like most hoteliers, Hyatt runs on the franchisor/franchisee system). Life and health insurance companies probably absorbed even larger uncompensated losses in policy payouts.
The Hyatt tragedy remains a classic model for the study of engineering ethics and errors. Gillum's chief engineer continues to share his experiences with others, in the hope that the mistakes which led to the Hyatt disaster will not be repeated.
After the disaster, the lobby was reconstructed with only one crossing on the second floor. Unlike the previous walkways, the new bridge is supported by several columns underneath it rather than being suspended from the ceiling. As a result, some floors of the hotel now have disconnected sections on opposite sides of the atrium, so it is necessary to go to the second floor to get to the other side.
The hotel later reopened, and has been renamed Hyatt Regency Crown Center. It has since been renovated and now serves as one of the city's most luxurious hotels.
Memorial
The accident is not marked in any way in the hotel. In 2008 the Skywalk Memorial Foundation announced a fundraising drive to build a garden and a fountain in Washington Square Park, about a block from the hotel commemorating the event. Hallmark had pledged $25,000 and the city has offered $200,000.
See also
Further reading
- Marshall, Richard D., [et al.]. Investigation of the Kansas City Hyatt Regency walkways collapse, U.S. Dept. of Commerce, National Bureau of Standards, 1982.
External links
- - includes photos of the failed walkway components
- - physics presentation and resources
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