The document discusses forensic structural engineering and provides an example case study of the Hyatt Regency walkway collapse. It defines forensic engineering as investigating failures from an engineering perspective to determine causes. A forensic investigation process is outlined including developing hypotheses, collecting evidence through documents, interviews, testing. The case study summarizes the 1981 Hyatt Regency walkway collapse which killed 111 people. Investigators discovered the walkway collapsed due to a failed connection between the walkway and support rods that was improperly changed from the design.

1. FORENSIC STRUCTURAL
ENGINEERING
PRESENTED BY:
RUKSANA BEEGAM E
EKC19CE044
GUIDED BY:
AJANA P
ASSISTANT PROFESSOR
EKC TECHNICAL CAMPUS
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2. CONTENT
• Introduction
• Goals of Forensic Engineering Investigation
• Qualification of the Forensic Engineer
• Failure of Structures
• Causes of Structural Failures
• Types of Failures
• Initiation of Failure Investigation
• General Investigation Process
• CASE STUDY: Hyatt Regency Walkway Collapse
• Conclusion
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3. INTRODUCTION
• Application of the engineering sciences to the investigation of failures or
performance problems
• Highly specialized field of engineering practice
• Requires engineering expertise and knowledge of legal procedures
• From an engineering perspective, forensic engineering deals with the investigation
and reconstruction of failures
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4. Goals of Structural Failure Investigations
• To determine the causes of failure
• To compare statements by witnesses or injured parties with physical evidence
• To ascertain whether an illegal or improper activity was causative
• To assess damage to materials, products or structures and evaluate repair estimate
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5. Qualification of Forensic Engineer
• Technical Competency
• Knowledge of Legal Procedures
• Detective Skills
• Effective Oral and Written Communication
• High Ethical Standards
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6. Failure of Structures
According to Jack Janney (1986), the structural failure can be divided into:
1. Structural Distress: an impairment of the strength or load response of a structure
which may limit its use as intended.
2. Structural Failure: the reduction of the capability of a structural system or
component to such a degree that it cannot safely serve its intended purpose.
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7. Failure of Structures (contd…)
3. Structural Collapse: Gross movement of major members or a
significant portion of a structural system manifested by the creation
of rubble from breakage of the members themselves and elements
supported by themselves.
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8. Failure of Structures (contd…)
• Gerald Leonards (1992) defines “failure” as an unacceptable difference between
expected and observed performance. This definition can be used to describe a
catastrophic failures as well as minor failures such as roof leaks.
• The ASCE Technical Council on Forensic Engineering has adopted the above
definition provided by Gerald Leonards.
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9. Causes of Structural Failure
Causes of failures fall into five general areas:
1. Design deficiencies
2. Construction deficiencies
3. Material deficiencies
4. Administrative deficiencies
5. Maintenance deficiencies
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10. Initiation of Failure Investigation
• Establishing a preliminary objective and scope of work,
• Checking on conflicts in interest,
• Executing a contract agreement, and
• Establishing an investigative plan.
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11. General Investigation Process
The steps involved are:
1. Definition of investigation objective
2. Collection of background information and documents
3. Initial site visit
4. Formation of investigation plan and project team
5. Formulation of initial failure hypotheses
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12. General Investigation Process (contd…)
6. Comprehensive document review
7. Site investigation, field testing, and sample collection
8. Structural analysis and laboratory testing
9. Revision of failure hypotheses
10. Final conclusion
11. Report
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13. CASE STUDY: Hyatt Regency Walkway
Collapse
Background:
• The Hyatt Regency Walkway Collapse was the worst structural failure in the
history of the United States
• 111 people were killed and more than 200 were injured.
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14. Sequence of Events
• The Hyatt Regency hotel opened in Kansas City, Missouri, USA in 1980
• It comprised a 40-story tower, an atrium, and a function block, housing all of the
hotel’s services
• Three walkways suspended from the atrium’s ceiling by six 32-mm-diameter
tension rods each spanned the 37-m distance between the tower and the function
block
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15. Sequence of Events (contd…)
• The 3rd and 4th floor walkways hung from the ceiling
• The 2nd floor walkway was suspended from the beams of the 4th floor walkway,
directly below the 4th floor walkway
• On the July 17, 1981, around 1500-2000 people occupied the atrium floor and the
suspended walkways to see a dance competition
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16. Sequence of Events (contd…)
• A loud crack echoed throughout the building and connections supporting the
ceiling rods that held up the 2nd and 4th floor walkways across the atrium failed.
• The 4th floor walkway collapsed onto the 2nd floor walkway and then both
walkways collapsed onto the crowded 1st floor atrium.
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17. Failure Hypothesis
Initially, the investigators had assumed two possibilities of the collapse as follows:
1. Walkways buckled from “harmonic vibration” set up by people swaying or
dancing at the same times. This wave like motion generated violent stress and
caused vibration failure of the structure.
2. Collapse due to inadequate design of structure.
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18. Investigation Approach
The investigation approach that had been carried out is as follows:
1. Eyewitness and Expert Interviews
2. Site Investigation
3. Connection Design Check and Document Study
4. Laboratory Test
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19. Eyewitness and Expert Interviews
• Roger McCarthy, an expert of failure analysis, had stated that there were telltale
signs in the skeleton of a structure well before it suffered vibration failure, and in
Hyatt Regency walkway collapse, there were no such signs.
• Eyewitness accounts gave another point that indicated there was a loud crack
echoed while the 2nd and 4th floor walkway crashed to the ground. Hence,
according to this, collapse was related to the sudden failure mechanism.
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20. Site Investigation
The following photographic evidence was taken by Dr. Lee Lowery, shortly after the
collapse:
Fig. 1. General view of the lobby floor, during
the 1st day of investigation (wikipedia)
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21. Walkway sections still remained
as a piece-form (wikipedia)
Photo of intact hanger rods from
4th floor walkway opening
(wikipedia)
Site Investigation (contd...)
Fig. 2. Fig. 3.
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22. Photo of still hanging 3rd floor
walkway (wikipedia)
Fig. 5. Photo of Deformed 4th floor beam
(wikipedia)
Site Investigation (contd...)
Fig. 4.
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23. Site Investigation (contd…)
• From the photographic evidence it was observed that there were no failure signs
on the walkway section, indicating that the collapse was not caused by inadequate
design of the section of the walkway.
• The photograph had provided significant proof to show that the walkway collapse
was most likely caused by connection failure.
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24. Connection Design Check and Document Study
The National Bureau of Standards (NBS) found that the details of the connection of
the walkway beam to the suspender was not constructed as drawn but was changed
by the contractor for constructability reason.
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25. Laboratory Test
Type of Connection Capacity(kN)
Original design 90
As-built 45
Table 1. Loading test result of connections
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26. Laboratory Test (contd…)
Analysis of these two connection details revealed the following:
• The original design of the rod hanger connection would have supported 90 kN,
only 60% of the 151 kN required by the Kansas City building code. This showed
that the design of the connection was inadequate.
• As-built, however, the connection only supported 30% of the minimum load
which explains why the walkways collapsed well below maximum load.
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27. Investigation Results
The National Bureau of Standards (NBS) discovered that the cause of this collapse
was quite simple: the rod hanger pulled through the box beam causing the
connection supporting the 4th floor walkway to fail.
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28. Conclusion of Case Study
Case study Structure Problem Main Finding
Hyatt Regency
Walkway collapse
Reinforcement
concrete
suspended
walkway, with
steel to steel
connection.
Walkway
suddenly
collapsed
Collapse due to
fracture of the brittle
connection. This
fracture of connection
was caused because
the contractors did not
follow the design
drawing.
Table 2. Conclusion of Case Study
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29. References
• Azizipour.M, Dalpasand.M, et al (2021) “Forensic Engineering Analysis applied
to flood control” – Vol. 594, ScienceDirect
• Balkaya.C, Etemadi.A (2020) “Collapsed RC-building failure mechanisms with a
Forensic Engineering Approach” – Vol. 34 Issue 5, ASCE
• Chou.J.S, Truong.D.N (2022) “Multiobjective forensic based investigation
algorithm for solving structural design problems” – Vol. 134, ScienceDirect
• Robert T. Ratay (2000) “Forensic Structural Engineering Handbook”
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30. THANK
YOU
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