BY: Arpit Modh (16BCH035) B.Tech Chemical Nirma University, Ahmedabad.

1. The Kansas
City Hyatt
Regency
Walkway
Collapse
“The Worst Structural
Disaster In the United States”
BY:
Arpit Modh
(16BCH035)
B.Tech Chemical
Nirma University,
Ahmedabad.

2. WHERE: Kansas City, Missouri
DATE: July 17, 1981
3rd
Floor Walkway Still Intact

3. • Two Walkways
Collapsed
• 114 People Lost
Their Life
• Failure of Hanger
Rod Connection
(4th Floor)
Kansas City Hyatt
July 17, 1981

5. Hotel Features
• The hotel had a grand lobby which featured a multistory
atrium crossed by three concrete walkways on the second,
third and fourth floors
• The hotel advertised to have many parties and events

6. Entrance to Hotel and Atrium
Kansas City Hyatt

7. Entranc
e
Hyatt General Layout

8. Background Of Walkway
• July 1980 – Most Modern Hotel in Kansas City finished.
• Consisted of 3 Buildings, 2 were connected by 3 walkways.

9. Tea-Dance Party Leads to
Disaster
• A party was held in the lobby
• Over 2,000 people were in attendance
• People crowded the walkways and the lobby below to watch the
dance competition
• The excess weight caused the fourth floor walkway to fall onto the
second floor walkway and both walkways collapsed onto the
crowded first floor
• The collapse left 114 dead and more than 200 injured
• This was the United States’ most devastating structural failure of the
time

10. Design Problems
• Havens proposed the modified design to simplify the assembly task
and to eliminate the need to thread the entire length of the rods
• However, the change in the design doubled the stress put forth on
the nut which was under the fourth floor beam and with the
change the nut had to support the weight of two walkways
instead of just one
• “The ultimate capacity actually available using the original
connection detail would have been approximately 60% of that
expected of a connection designed in accordance with AISC
Specifications” according to the National Building Specifications

11. On a preliminary design a note was made that the
hanging rods needed to have strength of 413MPa
but that was left out of the final design and so the
fabricator used hanger rods with only 248MPa pf
strength.

12. Walkway’s Original Design
beams as intermediate supports
hole at both ends of Flanges
aded single rod
Hanger for 2nd
and 4th
floor walkways (3rd
floor
alkway was separate entity)

13. Walkway as Constructed
•4th
floor box beams:
-Ends had 2 holes
-Outer hole connected to ceiling
-2 lower rods went through
inner holes to support second
floor walkway

14. Original Design Modified Design (was used)
The 2nd
and 4th
floor
walkways were
originally supposed to be
suspended
from the same rod and
held in place by nuts
The fabricator had
modified the design to use
two hanging rods and the
engineers approved the
change without checking
it

15. The hanger rod threads, washer andThe hanger rod threads, washer and
supporting nutsupporting nut
Note: the deformation in the washer caused the beam to slipNote: the deformation in the washer caused the beam to slip

16. CLOSE-UPS OF
SOME OF
THE 4TH
FLOOR
BEAMS

17. Why Did It Happen?
Combination of :Personnel
Errors
A. Design Deficiencies
B. Inadequate Oversight &
Review Process
C. Missed opportunities to
discover error
D. Poor Communication

18. Factors That Contributed to the
Collapse
• Fast Track Process
 Architectural design changes & conceptual re-designs
 Drafting Errors
 Checking errors-Shop Drawings
 Invalid initial design concept of hanger
Senior engineer personnel changes
 Phone changes w/o follow-up by detailer or engineer in writing

19. •Fabricators in-house engineer transferred fabricator’s partial shop
dwgs to outside firm who assumed connection was designed
•Engineers technician, checked piece size but not connection. (Not
Drawn or submitted)
•Outside Peer Review didn’t check
shop dwg
Factors (Continued)

20. •“Design Check” questions answers not verified
•In-house design check questions following atrium collapse were
not verified. No Follow Up
•Poor Testing & Inspection
Factors (Continued)

21. •No Structural Site Representation (Refused several times)
•Engineer Relied (ASSUMED) based on past projects on design of
connections by Fabricator, w/no follow-up by Project Manager
Factors (Continued)

22. Other Factors
• Resonating vibrations from dancing and music
• Greatly increased stress on box beams.
• Kansas City Building Code required for walkway:
• 100lbs/ft2
or 72,000 lbs for each walkway
• Actual load day of tragedy
• 9450 lbs (63 people @150lbs each)
• Design Lacked Redundancy

27. Procedures must be implemented that assure that allProcedures must be implemented that assure that all
connections are designed by a competent professionalconnections are designed by a competent professional
Peer reviews and design checks should include a review ofPeer reviews and design checks should include a review of
shop drawingsshop drawings
Lessons Learned

28. When questions come up look at surrounding issues for related
problems
EOR should be retained to provide full inspection during
construction of structure
Owner needs on site qualified representation
Lessons Learned

29. Design and construction is a collaborativeDesign and construction is a collaborative
process that requires professional integrity,process that requires professional integrity,
judgment, and integrity on the part of alljudgment, and integrity on the part of all
participantsparticipants
We have not yet clearly defined the nature ofWe have not yet clearly defined the nature of
the design and construction process and thethe design and construction process and the
information flow that is required for success ininformation flow that is required for success in
all respectsall respects
We have not learned to respect and teach theWe have not learned to respect and teach the
history of the profession and fully disseminatehistory of the profession and fully disseminate
information of problems that occurinformation of problems that occur
Lessons Not Learned

30. “It wasn’t a matter of doing something wrong, they just never did it at
all. Nobody ever did any calculations…. It got built without anybody
figuring out if it would be strong enough.”
• Patrick McLarny, attorney representing state of MO.

31. In Conclusion
• The two structural engineers lost their Professional Engineering
licenses and are no longer able to practice in the states of Missouri
and Texas
• Both are now practicing in other states
• A number of firms were bankrupt
• Many expensive legal suits were settled out of court