Kansas City Hyatt Regency Walkway
Collapse
By: Ian Thompson
Stephen Conlon
David Martin
Laura Devane
Design and Construction
 Opened to the public in 1980 after four years of design and construction
 Consisted of a 40-story tower, an atrium, a function block, and housing all
of the hotel’s services
 Three walkways suspended from the atrium’s ceiling by six 32-mmdiameter tension rods, each spanned the 37-m distance between the tower
and the function block
 The 2nd floor walkway suspended from the beams of the 4th floor
walkway
 While the 3rd and 4th floor walkways hung from the ceiling
Collapse
• July 17, 1981, between 1500 and 2000 people inundated the atrium floor
and the suspended walkways to see a local radio station’s dance
competition
• A loud crack echoed throughout the building and the 2nd and 4th floor
walkways crashed to the ground
• Killed 114 people and injured over 200 others
• Worst structural failure in the history of the United State
Causes of Failure
 Originally, 2nd and 4th floor walkways were to be
suspended from the same rod and held in place by nuts
(fig-1)
 Preliminary design specified a strength of 413 MPa for
the hanger rods which was omitted on the final structural
drawings
 Following the general notes in the absence of a
specification on the drawing, the contractor used hanger
rods with only 248 MPa of strength
 This original design, however, was highly impractical
because it called for a nut 6.1 meters up the hanger rod
and did not use sleeve nuts
 Contractor modified this detail to use 2 hanger rods
instead of one (as shown in fig-2) and the engineer
approved the design change without checking it.
 Design change doubled the stress on the nut under the
fourth floor beam
 Nut supported the weight of 2 walkways instead of one
Original(Fig.1)
As-built(Fig.2)
Causes of Failure
 Rod hanger pulled through the
box beam causing the
connection supporting the 4th
floor walkway to fail
Technical Concerns
 Neither the original nor the as-built design for
the hanger rod satisfied the Kansas City
building code making the connection failure
inevitable
 The toe-to-toe channels used in the Hyatt
Regency provided for weak welding which
allowed the nut to pull through the channel/box
beam assembly initiating the collapse
 A back-to-back channel design using web
stiffeners when necessary (fig-3) or the use of
bearing crossplates in conjunction with the toeto-toe channels (fig-4) would have made the
connection much stronger making it much more
difficult for the nut to pull through
Fig-3
Fig-4
Procedural Concerns
 Collapse highlighted the lack of established procedures for design changes
as well as the confusion over who is responsible for the integrity of shop
details
 It is important for all parties to fully understand and accept their
responsibilities in each project
 The engineer of record should design and detail all nonstandard
connections
 New designs should be thoroughly checked
 All of the contractor's modifications to design details should require written
approval from the engineer of record
Conclusion
 Neglecting to check the safety and load capacity of a crucial hanger even
once shows complete disregard for the public welfare
 Ethical engineers should check and recheck their work in order to be able
to properly assure the public of a building's structural integrity
 Also, the high number of fatalities resulting from the walkway's collapse
raises the questions of whether the factor of safety required for a building
should be proportional to the possible consequences of it collapse