1981 жылғы Канзас-Ситидегі Hyatt Regency құрылысының күлтуі

1981 structural collapse in Kansas City, Missouri

Two overhead walkways in the Hyatt Regency Hotel in Kansas City, Missouri, collapsed on July 17, 1981, killing 114 people and injuring 216. Loaded with partygoers, the concrete and glass platforms crashed onto a tea dance in the lobby. Kansas City society was affected for years, with the collapse resulting in billions of dollars of insurance claims, legal investigations, and city government reforms. The Hyatt had been built just a few years before, during a nationwide pattern of fast tracked large construction with reduced oversight and major failures. Its roof had partially collapsed during construction, and the ill conceived skywalk design progressively degraded due to a miscommunication loop of corporate neglect and irresponsibility. An investigation concluded that it would have failed even under one third of the weight it held that night. Convicted of gross negligence, misconduct and unprofessional conduct, the engineering company lost its national affiliation and all engineering licenses in four states, but was acquitted of criminal charges. Company owner and engineer of record Jack D. Gillum eventually claimed full responsibility for the collapse and its obvious but unchecked design flaws, and he became an engineering disaster lecturer. The disaster contributed many lessons and reforms to engineering ethics and safety, and to emergency management. It was the deadliest non deliberate structural failure since the collapse of Pemberton Mill over 120 years earlier, and remained the second deadliest structural collapse in the United States until the collapse of the World Trade Center towers 20 years later.

The Kansas City Star described the national climate of the late 1970s as "high unemployment, inflation and double digit interest rates [that added] pressure on builders to win contracts and complete projects swiftly". Described by the newspaper as fast tracked, construction began in May 1978 on the 40 story Hyatt Regency Kansas City. There were numerous delays and setbacks, including the collapse of of the roof. The newspaper observed that "Notable structures around the country were failing at an alarming rate", which included the 1979 Kemper Arena roof collapse

The hotel's lobby was its defining feature, with a multi story atrium spanned by elevated walkways suspended from the ceiling. These steel, glass and concrete crossings connected the second, third and fourth floors between the north and south wings. The walkways were about 120 feet (37 m) long The fourth level walkway was directly above the second level walkway.

The Kansas City Star hired architectural engineer Wayne G. Lischka and national engineering firm Simpson, Gumpertz, and Heger Inc. to investigate the collapse, and Lischka discovered a change to the original design of the walkways. Edward Pfrang, lead investigator for the National Bureau of Standards, characterized the neglectful corporate culture surrounding the entire Hyatt construction project as "everyone wanting to walk away from responsibility". with the second floor walkway hanging directly under the fourth floor walkway. The fourth floor walkway platform was supported on three cross beams suspended by the steel rods retained by nuts. The cross beams were box girders made from C channel strips welded together lengthwise, with a hollow space between them. The original design by Jack D. Gillum and Associates specified three pairs of rods running from the second floor walkway to the ceiling, passing through the beams of the fourth floor walkway, with a nut at the middle of each tie rod tightened up to the bottom of the fourth floor walkway, and a nut at the bottom of each tie rod tightened up to the bottom of the second floor walkway. Even this original design supported only 60% of the minimum load required by Kansas City building codes. Havens Steel Company had manufactured the rods, and the company objected that the whole rod below the fourth floor would have to be threaded in order to screw on the nuts to hold the fourth floor walkway in place. These threads would be subject to damage as the fourth floor structure was hoisted into place. Havens Steel proposed that two separate and offset sets of rods be used: the first set suspending the fourth floor walkway from the ceiling, and the second set suspending the second floor walkway from the fourth floor walkway. This design change would be fatal. In the original design, the beams of the fourth floor walkway had to support only the weight of the fourth floor walkway, with the weight of the second floor walkway supported completely by the rods. In the revised design, however, the fourth floor beams supported both the fourth and second floor walkways, but were strong enough only for 30% of that load. During the failure, the box beams split along the weld and the nut supporting them slipped through the resulting gap, which was consistent with reports that the upper walkway at first fell several inches, after which the nut was held only by the upper side of the box beams; then the upper side of the box beams failed as well, allowing the entire walkway to fall in a cascading failure. A court order was required to retrieve the skywalk pieces from storage for examination. Investigators concluded that the underlying problem was a lack of proper communication between Jack D. Gillum and Associates and Havens Steel. In particular, the drawings prepared by Gillum and Associates were only preliminary sketches, but Havens Steel interpreted them as finalized drawings. Gillum and Associates failed to review the initial design thoroughly, and engineer Daniel M. Duncan accepted Havens Steel's proposed plan via a phone call without performing necessary calculations or viewing sketches that would have revealed its serious intrinsic flaws—in particular, doubling the load on the fourth floor beams. The single largest award was about $12 million, for a victim who required full time medical care. That lawsuit yielded $10 million, including $6.5 million dedicated as donations to charitable and civic endeavors that Hallmark called a "healing gesture to help Kansas City put the tragedy of the skywalks' collapse behind it." Each of the approximately 1,600 hotel occupants from that night was unconditionally offered $1000, of which 1,300 accepted by the deadline. Every defendantincluding Hallmark Cards, Crown Center Corporation, architects, engineers, and the contractordenied all legal liability, including that of the egregious engineering faults. The disaster provides a case study teaching first responders the "all hazards approach" to multiple disciplines across jurisdictions, and teaching university students in engineering ethics classes how the smallest personal responsibility can impact the biggest projects with the worst possible results. quotation | quote=[The skywalk design] is one of the worst examples of people trying to push off their responsibilities to other parts of the team Since the Hyatt, there has been a lot of activity in the engineering profession to address quality, the final product and how you attain quality. The steps taken after the Hyatt helped the industry recover from failure. | source=Paul Munger, chairman of the Missouri architectural board

A memorial was dedicated by Skywalk Memorial Foundation, a nonprofit organization established for victims of the collapse, on November 12, 2015, in Hospital Hill Park across the street from the hotel. It included a $25,000 donation from Hallmark Cards. the owner of the engineering company and an engineer of record for the Hyatt project, occasionally lectured at engineering conferences for years after the tragedy. Claiming full responsibility and disturbed by his memories "365 days a year", he said he wanted "to scare the daylights out of them" in the hope of preventing future mistakes.