Hyatt Regency Hotel Disaster Kansas City
Introduction
Construction on the Hyatt Regency Hotel in Kansas City Missouri, began in 1978 and the hotel open
on 1st July 1980. The building consists of a 40 storey hotel tower and a conference facilities block
connected by a multi storey atrium. This atrium included a freestanding staircase reaching the first
floor from ground level, and three “skywalk” concrete and steel walkways suspended from the
ceiling. These walkways crossed the width of the atrium at the second, third and fourth floors and
were supported by 32mm steel tie rods from the ceiling. The second floor skywalk was located
directly underneath the fourth floor skywalk while the third floor walkway was offset from the other
two. During construction the detail of the connection between the fourth and second floor skywalk
hanging rods was changed to make it easier to construct. Now the second floor walkway was hung
from the fourth floor skywalk beams. The building which was Kansas City’s tallest was part of a plan
devised by Edward Larrabee Barnes and designed by a new architect firm PBNDML. On 17 th July
1981, a tea dance was held in the atrium which drew
over 2000 visitors. While some of the guests were
dancing on the ground floor, many stood and danced
on the skywalks observing the activities below. At
7.05 pm the packed second and fourth floor
walkways failed and fell to the ground below. The
separate third floor skywalk was left undamaged.
This incident resulted in 114 people dying and more
than 200 sustaining injuries.
Hyatt Regency Hotel Atrium
Technical Analysis of Failure
The failure of walkways 2 and 3 was down to the lack of communication between the Engineering
Company in charge of the project and the steel company who manufactured the walkways. The
design originally intended the walkways to be supported by three cross beams suspended from
three steel rods. These rods were intended to run all the way from the 2nd floor to the ceiling passing
through the 4th floor walkway. These rods would be threaded through the beams of the walkways
and held in place by nuts. However, the steel company decided to make a design change. This
change in design was approved by the Engineers without any new calculations being made. The new
design would mean that instead of the single threaded rods running from the 2nd floor through the
4th floor to the ceiling, shorter rods would be used. The 2nd floor walkway would now have to be
supported by the 4th floor beam. This was the fatal design flaw.
Due to the addition of a second rod, the load on the nut connecting the fourth floor segment was
increased. The stress of the nut under the 4th floor beam doubled and it was now supporting the
weight of two walkways instead of one. The original load for the single rod was 90Kn but the
alteration increased the load to 181Kn. The box beams were welded horizontally and therefore
could not hold the weight of the two walkways.
How the structure failed
The design of the cross beams becomes a factor with the new design. The cross beams are two C
channels welded toe to toe. The bolts are placed in this welded joint the weakest structural part of
the cross beams. It is evident that this is a weak part of the structure. When we couple this with the
fatal design flaw highlighted above where the bottom nut on the crossbeam is taking double the
load it leads to disaster.
At the time of failure we must consider the circumstances. There were 63 people on the walkway
itself at the time adding roughly another 50KN of imposed load. Take into account also the
vibrations from people walking and dancing on the walkway at this point.
In these circumstances the bolt connections in the cross beams of the fourth floor simply cannot
handle the load. The nut that is taking twice the load it should is under such load that it begins to
deform the underside flange of the cross beam and causes a fracture at the weld joint until the joint
suddenly fails. The box beam splits at the weld and the nut supporting it tears through. This process
starts at mid span and the remaining tie rods are unable to support the greater loads thus the
structure collapses.
It can be clearly seen in this photo how the cross
beam has split with the nut and washer tearing
through the welded joint that could no longer
support the loads being exerted.
Tests carried out after the disaster on some
actual undamaged samples proved that the
ultimate strength of the welds and box beams
was less than the applied load (i.e. twice the
originally calculated dead load) from the two
suspended floors.
Consequences of Disaster
After the collapse of the walkway an investigation was carried out by the Missouri Board of
Architects, Professional Engineers and Land Surveyors. After the investigations a complaint was
against Daniel M. Duncan, Jack D. Gillum, and G.C.E. International, Inc., charging gross negligence,
incompetence, misconduct and unprofessional conduct in the practice of engineering in connection
with their performance of engineering services in the design and construction of the Hyatt Regency
Hotel. During the trial that occurred after the complaint was made the representatives of G.C.E. tried
to deny that they had heard anything about the change in design.
However Gillum had approved the final drawings and as a result, himself and Duncan both lost their
engineering licences in the states of Misouri and Texas and their membership of ASCE. G.C.E. had its
certificate of authority as an engineering firm revoked but was cleared of criminal negligence.
After the disaster $140 million was paid out in damages to victims and their families, most of which
was paid by the Crown Center Coroporation. ASCE also adopted a report that said that structural
engineers have full responsibility for design projects.
The lobby was reconstructed and there is only one crossing on the second floor with the walkway
supported by columns rather than being suspended from the roof. Now it is necessary to go to the
ground floor and up again as some floors have disconnected sections on opposite sides of the
atrium. The Hotel is now renamed the Hyatt Regency Crown Center and the accident is marked in
no way on the Hotel.