Kansas City, Missouri

HYATT REGENCY WALKWAY COLLAPSE

Hyatt Regency Walkway Collapse

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 on July 1, 1980 after construction delays including an incident on October 14, 1979, when 2,700 square feet of the atrium roof collapsed because one of the roof connection 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.

Background

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.

Background

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.

Kansas City, Missouri

DISASTER

A major cause of fatalities was the landing of the concrete 4th floor walkway onto the crowded 2nd floor walkway, both seen here.

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.

Disaster

Construction difficulties 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 both walkways.

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 on top of the other and then into the lobby below.

Difference between the design and construction of the walkway support

WALKWAY SUPPORT SYSTEM

View of the 4th f loor support beam which fell, together with support rod

SUPPORT BEAM WHICH FELL

View of the Lobby Floor

INVESTIGATION

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.

Investigation

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.

Investigation

Investigators eventually determined that this design supported only 60% of the minimum load required by Kansas City building codes.

Investigation

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 thread would probably have been damaged beyond use as the structure for the fourth floor was hoisted into position.

Investigation

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.

Investigation

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, Haven’s proposed design could bear only 30% of the mandated minimum load.

Investigation

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.

Investigation

Investigators concluded that the basic problem was a lack of proper communications 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 Haven’s proposed plan without performing basic calculations that would have revealed its flaws.

AFTERMATH

Aftermath view. The 4th floor and 2nd floor walkways were positioned at the now boarded entrances. A parallel 3rd floor walkway to the left was left intact.

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.

Aftermath

While Jack D. Gillum and Associates itself was cleared of criminal negligence, it was stripped of its license to be an engineering firm.

Aftermath

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.

Life and health insurance companies probably absorbed even larger uncompensated losses in policy payouts.

Aftermath

The Hyatt tragedy remains a classic model for the study of engineering ethics and errors.

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.

Aftermath

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.