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38 Years Ago Today; The Hyatt Regency walkway collapse in KC - 114 dead
https://en.wikipedia.org/wiki/Hyatt_Regency_walkway_collapse
Locations of the second- and fourth-story walkways, which both collapsed into the lobby of the Hyatt Regency hotel
On July 17, 1981, two walkways collapsed at the Hyatt Regency Kansas City hotel in Kansas City, Missouri, one directly above the other. They crashed onto a tea dance being held in the hotel's lobby, killing 114 and injuring 216. It was the deadliest structural collapse in American history until the collapse of the World Trade Center towers 20 years later.
Background
Construction began in May 1978 on the 40-story Hyatt Regency Kansas City. There were numerous delays and setbacks, including the collapse of 2,700 square feet (250 m2) of the roof. Nonetheless, the hotel officially opened on July 1, 1980.
The hotel's lobby was one of its defining features, which incorporated 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 approximately 120 ft (37 m) long and weighed approximately 64,000 lb (29,000 kg). The fourth-level walkway was directly above the second-level walkway.
Collapse
Aftermath of the walkway collapse
Approximately 1,600 people gathered in the atrium for a tea dance on the evening of Friday, July 17, 1981. The second-level walkway held approximately 40 people at approximately 7:05 p.m., with more on the third and an additional 16 to 20 on the fourth. The fourth-floor bridge was suspended directly over the second-floor bridge, with the third-floor walkway offset several yards from the others. Guests heard popping noises moments before the fourth-floor walkway dropped several inches, paused, then fell completely onto the second-floor walkway. Then both walkways fell to the lobby floor.
The rescue operation lasted 14 hours. Survivors were buried beneath steel, concrete, and glass which the fire department's jacks could not move. Volunteers responded to an appeal and brought jacks, torches, compressors, jackhammers, concrete saws, and generators from construction companies and suppliers. They also brought cranes and forced the booms through the lobby windows to lift debris. Kansas City emergency medical director Joseph Waeckerle directed the effort. The dead were taken to a ground floor exhibition area as a makeshift morgue, and they used the hotel's driveway and front lawn as a triage area. They instructed those who could walk to leave the hotel to simplify the rescue effort, and they gave morphine to those who were mortally injured. Often, rescuers had to dismember bodies to reach survivors among the wreckage. A surgeon had to amputate one victim's crushed leg with a chainsaw.
Water flooded the lobby from the hotel's ruptured sprinkler system and put trapped survivors at risk of drowning. Mark Williams spent more than nine hours pinned underneath the lower skywalk with both legs dislocated, and he nearly drowned before the water was shut off. Visibility was poor because of dust and because the power had been cut to prevent fires. A total of 29 people were rescued from the rubble.
Investigation
Investigators found that the collapse was the result of changes to the design of the walkway's steel tie rods.
The Kansas City Star hired architectural engineer Wayne G. Lischka to investigate the collapse, and he discovered a significant change to the original design of the walkways. The Star and its associated publication the Kansas City Times won a Pulitzer Prize in 1982 for their coverage of the collapse.
The two walkways were suspended from a set of 1.25-inch-diameter (32 mm) steel tie rods, 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 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 to the ceiling. Even this original design supported only 60% of the minimum load required by Kansas City building codes.
Havens Steel Company manufactured the rods, and they 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, therefore, 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.
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, despite being only strong enough for 30% of that load.
The serious flaws of the revised design were compounded by the fact that both designs placed the bolts directly through a welded joint connecting two C-channels, the weakest structural point in the box beams. The original design was for the welds to be on the sides of the box beams, rather than on the top and bottom. Photographs of the wreckage show excessive deformations of the cross-section. 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.
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 interpreted them as finalized drawings. Gillum and Associates failed to review the initial design thoroughly and accepted Havens' proposed plan 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. It was later revealed that Gillum and Associates approved the design changes over the phone.
Aftermath
The Missouri Board of Architects, Professional Engineers, and Land Surveyors found the engineers at Jack D. Gillum and Associates who had approved the final drawings to be culpable of gross negligence, misconduct, and unprofessional conduct in the practice of engineering. They were acquitted of all the crimes with which they were initially charged, but the company lost its engineering licenses in the states of Missouri, Kansas, and Texas, as well as its membership with the American Society of Civil Engineers (ASCE).
At least $140 million (equivalent to $334 million in 2018) was awarded to victims and their families in subsequent civil lawsuits; a large amount of this money was from Crown Center Corporation, a subsidiary of Hallmark Cards which was the owner of the hotel real estate; Hyatt operated the hotel for a fee as a management company and did not own the building.
The Hyatt collapse remains a classic model for the study of engineering ethics and errors, as well as disaster management. Jack D. Gillum (1928–2012) was an engineer of record for the Hyatt project, and he occasionally shared his experiences at engineering conferences in the hope of preventing future mistakes.
Several rescuers suffered considerable stress due to their experience and later relied upon each other in an informal support group. Jackhammer operator "Country" Bill Allman died by suicide The hotel was renamed the Hyatt Regency Crown Center in 1987, and again the Sheraton Kansas City at Crown Center in 2011. It has been renovated numerous times since, though the lobby retains the same layout and design. A memorial was dedicated by Skywalk Memorial Foundation, a non-profit organization established for victims of the Hyatt collapse, on November 12, 2015 in Hospital Hill Park across the street from the hotel.
</snip>
Locations of the second- and fourth-story walkways, which both collapsed into the lobby of the Hyatt Regency hotel
On July 17, 1981, two walkways collapsed at the Hyatt Regency Kansas City hotel in Kansas City, Missouri, one directly above the other. They crashed onto a tea dance being held in the hotel's lobby, killing 114 and injuring 216. It was the deadliest structural collapse in American history until the collapse of the World Trade Center towers 20 years later.
Background
Construction began in May 1978 on the 40-story Hyatt Regency Kansas City. There were numerous delays and setbacks, including the collapse of 2,700 square feet (250 m2) of the roof. Nonetheless, the hotel officially opened on July 1, 1980.
The hotel's lobby was one of its defining features, which incorporated 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 approximately 120 ft (37 m) long and weighed approximately 64,000 lb (29,000 kg). The fourth-level walkway was directly above the second-level walkway.
Collapse
Aftermath of the walkway collapse
Approximately 1,600 people gathered in the atrium for a tea dance on the evening of Friday, July 17, 1981. The second-level walkway held approximately 40 people at approximately 7:05 p.m., with more on the third and an additional 16 to 20 on the fourth. The fourth-floor bridge was suspended directly over the second-floor bridge, with the third-floor walkway offset several yards from the others. Guests heard popping noises moments before the fourth-floor walkway dropped several inches, paused, then fell completely onto the second-floor walkway. Then both walkways fell to the lobby floor.
The rescue operation lasted 14 hours. Survivors were buried beneath steel, concrete, and glass which the fire department's jacks could not move. Volunteers responded to an appeal and brought jacks, torches, compressors, jackhammers, concrete saws, and generators from construction companies and suppliers. They also brought cranes and forced the booms through the lobby windows to lift debris. Kansas City emergency medical director Joseph Waeckerle directed the effort. The dead were taken to a ground floor exhibition area as a makeshift morgue, and they used the hotel's driveway and front lawn as a triage area. They instructed those who could walk to leave the hotel to simplify the rescue effort, and they gave morphine to those who were mortally injured. Often, rescuers had to dismember bodies to reach survivors among the wreckage. A surgeon had to amputate one victim's crushed leg with a chainsaw.
Water flooded the lobby from the hotel's ruptured sprinkler system and put trapped survivors at risk of drowning. Mark Williams spent more than nine hours pinned underneath the lower skywalk with both legs dislocated, and he nearly drowned before the water was shut off. Visibility was poor because of dust and because the power had been cut to prevent fires. A total of 29 people were rescued from the rubble.
Investigation
Investigators found that the collapse was the result of changes to the design of the walkway's steel tie rods.
The Kansas City Star hired architectural engineer Wayne G. Lischka to investigate the collapse, and he discovered a significant change to the original design of the walkways. The Star and its associated publication the Kansas City Times won a Pulitzer Prize in 1982 for their coverage of the collapse.
The two walkways were suspended from a set of 1.25-inch-diameter (32 mm) steel tie rods, 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 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 to the ceiling. Even this original design supported only 60% of the minimum load required by Kansas City building codes.
Havens Steel Company manufactured the rods, and they 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, therefore, 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.
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, despite being only strong enough for 30% of that load.
The serious flaws of the revised design were compounded by the fact that both designs placed the bolts directly through a welded joint connecting two C-channels, the weakest structural point in the box beams. The original design was for the welds to be on the sides of the box beams, rather than on the top and bottom. Photographs of the wreckage show excessive deformations of the cross-section. 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.
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 interpreted them as finalized drawings. Gillum and Associates failed to review the initial design thoroughly and accepted Havens' proposed plan 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. It was later revealed that Gillum and Associates approved the design changes over the phone.
Aftermath
The Missouri Board of Architects, Professional Engineers, and Land Surveyors found the engineers at Jack D. Gillum and Associates who had approved the final drawings to be culpable of gross negligence, misconduct, and unprofessional conduct in the practice of engineering. They were acquitted of all the crimes with which they were initially charged, but the company lost its engineering licenses in the states of Missouri, Kansas, and Texas, as well as its membership with the American Society of Civil Engineers (ASCE).
At least $140 million (equivalent to $334 million in 2018) was awarded to victims and their families in subsequent civil lawsuits; a large amount of this money was from Crown Center Corporation, a subsidiary of Hallmark Cards which was the owner of the hotel real estate; Hyatt operated the hotel for a fee as a management company and did not own the building.
The Hyatt collapse remains a classic model for the study of engineering ethics and errors, as well as disaster management. Jack D. Gillum (1928–2012) was an engineer of record for the Hyatt project, and he occasionally shared his experiences at engineering conferences in the hope of preventing future mistakes.
Several rescuers suffered considerable stress due to their experience and later relied upon each other in an informal support group. Jackhammer operator "Country" Bill Allman died by suicide The hotel was renamed the Hyatt Regency Crown Center in 1987, and again the Sheraton Kansas City at Crown Center in 2011. It has been renovated numerous times since, though the lobby retains the same layout and design. A memorial was dedicated by Skywalk Memorial Foundation, a non-profit organization established for victims of the Hyatt collapse, on November 12, 2015 in Hospital Hill Park across the street from the hotel.
</snip>
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