HYATT REGENCY WALKWAY COLLAPSE INTRODUCTION • On July 17, 1981, two suspended walkways collapsed in the Hyatt Regency Hotel in Kansas City, Missouri during a dance festival • As the United States' most devastating structural failure—in terms of loss of life and injuries—the Kansas City Hyatt Regency walkways collapse left 114 dead and an excess of 200 injured. • In addition, millions and millions of dollars in costs related to lawsuits, etc., resulted from the collapse, and hundreds of lives were adversely affected. • A powerful, painful lesson about the meaning and practice of ethics in engineering.
What part of the walkway do you think failed? • What part of the support structure could have failed to cause both the second and fourth-floor walkways to fail? • What evidence would you look for to decide what part actually failed?
HYATT REGENCY WALKWAY COLLAPSE:BACKGROUND TO THE CASE March 1976 • Crown Center Redevelopment Corporation began to design Hyatt Regency Hotel in Kansas City, Missouri April 4, 1978 • Actual contract entered into by Gillum-Colaco, Inc., a Professional Engineering Firm, G.C.E. and the architect, PBNDML Architects, Planners, Inc. G.C.E. agreed to provide "all structural engineering services for a 750-room hotel project located at 2345 McGee Street, Kansas City, Missouri." • During that time, Jack D. Gillum (the supervisor of the professional engineering activities of GCE.) and Daniel M. Duncan (working under the direct supervision of Gillum, the engineer responsible for the actual structural engineering work on the Hyatt project) assisted Crown Center Redevelopment Corporation (the owner) and PBNDML Architects, Planners, Inc. (the architect on the project) in developing plans for the hotel project and deciding on its basic design. Spring 1978: Construction begins on hotel December 1978 • Eldridge Construction Company, general contractor on the Hyatt project, enters into subcontract with Havens Steel Company. Havens agrees to fabricate and erect the atrium steel for the Hyatt project.
HYATT REGENCY WALKWAY COLLAPSE • The original design consisted of long suspension rods hanging down from the ceiling. These hanging suspension rods would then support upper and lower beams. The two beams would, in turn, bear the weight of the two walkway floors. • In the proposed design, the rods were hung from the ceiling, then the upper deck beams were threaded on and slid up the rods, then heavy washers and nuts where run up the rods to support the upper beam. • The lower beams were then similarly fitted onto the rods at the bottom, and again were supported with nuts and washers under each end. • This detail was shown on the engineering drawings that had been submitted to the fabricator, Havens Steel
Wide flange beams were used on either side of the walkway upon which was hung a box beam • A clip angle welded to the top of the beam was connected to the flange beams with bolts • One end of the walkway was welded to a fixed plate while a sliding bearing supported the other end • Each box beam of the walkway was supported by a washer and nut which was threaded onto the supporting rod • The beams consisted of two 8-inch channel sections welded toe to toeto make up a box beam. • The ends of the box beams were then drilled to receive the rods. • The box beam consisted of two 8 x 8.5 MC channels
HYATT REGENCY WALKWAY COLLAPSE • The walkways were suspended from the ceilings by long rods. • The rod would pass through the top walkway and on down to the bottom walkway. • Under each walkway, a load-carrying nut would be used on each of the rods to carry the load of the walkway. • Since the original design called for running the nuts 30 feet up the rods, the entire length of the rods had to be threaded. • Threading 30 feet of rod is difficult and costly. • The fabricator decided to modify the original design to make it easier and less costly to construct.
Over a year before the collapse (1979), the design of the walkway hanger rod connections was changed in a series of events and mis-communications between the fabricator (Havens Steel Company) and the engineering design team (GCE) • Havens Steel, the fabricator, changed the design from a one-rod to a two-rod system to simplify the assembly task.
HYATT REGENCY WALKWAY COLLAPSE • This design change, however, put a double load on the connector rod. • The deviations from the original design are as follows: • One end of each support rod was attached to the atrium’s roof cross beams • The bottom end went through the box beam and attached with a washer and nut • A second rod was attached to the box beam 4 inches from the first rod • They cut the rods in half and ran those halves from the roof to the top walkway and placed nuts • They then drilled another set of holes, which was offset 4 inches inward along the axis of the box beam, in the top walkway and hung the other halves of the rods from the top walkway.
In the modified design, the fabricator had to thread only about 6 inches ofeach end of each rod, a considerably easier task. The workers failed to realize that this doubled the load on the nuts under the top walkway compared to the original design. In the original design, the load (weight) for each hanger rod was to be 90 kN. With the revised design, the load was increased to 180 kN on the fourth floor box beam connections The National Bureau of standards (NBS) discovered that the cause of the walkway collapse was that the rod hanger, attached to the ceiling and to the walkways, pulled through the box bean due to lack of redundancy of load-bearing factors, causing the connection supporting the 4th walkway to collapse onto the 2rd floor.
HYATT REGENCY WALKWAY COLLAPSE • Notice in diagram 1 that in the walkway design, Nut 1 supports only the walkway above it. • The weight of the second walkway is supported through the rod. In the walkway built, Nut 1 not only holds the weight of the walkway above it, but also the hanging weight of the second walkway and the rods used to support it. • This proved to be more stress than the structure on which Nut 1 was supported and it could not hold the extra load of the other walkway. • Since the box beams were longitudinally welded, as proposed in the original design, they could not hold the weight of the two walkways
HYATT REGENCY WALKWAY COLLAPSE • Suppose a long rope is hanging from a tree, and two people are holding onto the rope -- one near the top and one near the bottom. Under the conditions that each person can hold their own body weight, and that the tree and rope can hold both people, the structure would be stable. • However, if one person was to hold onto the rope, and the other person was hanging onto the legs of the first, then the first person’s hands must hold both people’s body weights, and, thus, the grip of the top person would be more likely to fail.
Original Design Modified Design Design Change for the Worst
Introduction to Forensic Engineering • Forensic Engineering involves the investigation, testing and analysis to determine the cause of engineering failures. • Forensic engineers use their specialized knowledge of deterioration mechanisms, behavior of construction materials, construction methods, and repair procedures to determine the most suitable solution to the why technology fails. • Forensic engineering reports are often used as evidence for litigation support and many forensic engineers serve as expert witnesses in courts or investigations. • After an accident, forensics engineers examine broken parts and bring together a list of probable failure mechanisms to be investigated. Interviews are conducted to determine a sequence of events. • Drawings, specifications, and operational procedures are reviewed. As-built dimensions and operating parameters are compared to design requirements
Introduction to Forensic Engineering Typical Foci of Forensic Engineers Include: • Fire Investigations • Industrial Accidents (explosions, disasters) • Product Liability Engineering • Traffic Accident Reconstruction • Transportation Disaster Investigation (airplane, railroad crashes) • Civil Engineering Investigation (building collapses, building systems failures, • Environmental Systems Failures
Forensic Analysis of Disaster • What was the (physical) cause of the collapse? • Shoddy structural materials (substandard inferior steel?) • Bad (slag and/or shallow) welds? • Faulty construction? • Were essential bolts and washers missing or not fastened? • Unexpected loads? • Did all the dancing create a harmonic vibration not taken into in the original design? • Fundamental Design flaws? • The researchers could only conclude that it was a fundamental flaw in the design stage
Sociotechnical Systems Analysis • Technical Factors • Fundamental Flaws in the Engineering Design Process • Human Factors • Unprofessional behavior of individuals involved • Organizational Factors • Major mis-communication between various organizations involved • Careless managerial practices in various organizations • Socio-cultural Factors • Neglectful Local/State Inspection Administration
ETHICS T O S-C H
CAUSAL ANALYSIS OF THE DISASTER: TECHNICAL FACTORS Three Major Technical Factors can be identified: • Abrupt changes which resulted in high concentrations of stress on particular areas • The original design was changed from one where the walkways were supported by two nuts on one rod to one that was supported by two nuts on two rods causing the amount of stress on each nut to increase. • Lack of consideration for every force acting on particular connections • By changing the design to two rods and not calculating new data for the design change, a lack of consideration for all forces acting on that nut was prevalent. • Failure to take motion and rotation into account in the design • The walkways were not designed for excessive motion. The walkways of the Hyatt Regency were designed so that guests could pass from one side of the hotel to the other They were not planned to be used as dance floors. Unfortunately, the failure to take motion and rotation into account in the design proved to be deadly when the fourth floor.
Fundamental Causes of Structural Failure • Improper design due to lack of consideration of all forces acting on a connection or material, especially those associated with volume changes • Improper design utilizing abrupt section changes resulting in stress concentrations • Insufficient provisions for rotation and movement • Improper preparation of mating surfaces and installation connections • Degradation of materials in a connection • Lack of consideration of large residual stresses resulting from manufacture or fabrication
CAUSAL ANALYSIS OF THE DISASTER: ORGANIZATIONAL FACTORS COMMUNICATION FAILURES • The fabricator of the steel for the walkways and hanging rods, Havens Steel, in sworn testimony before the administrative judicial hearings after the accident, claimed that their company (Havens) telephoned the engineering firm (GCE) for approval change to the box-beam/hanging-rod design • G.C.E., for their part, denied ever receiving such a call from Havens. • Havens claims that on February 16, 1979, they sent 42 shop drawings—including the all-important revised Shop Drawing 30 and Erection Drawing E-3) to GCE • Havens claims that on February 26, 1979, GCE returned the set of drawings to Havens, along with Gillum’s engineering review seal, authorizing construction • GCE claimed miscommunication because they argued that the drawings prepared and sent to Haven were only preliminary sketches but were interpreted by Havens as finalized drawings.
Communication Breakdown in the Hyatt-Regency Case • This communication failure resulted in confusion about engineering design responsibility of at several levels of interaction between the GCE and Havens Steel, which ultimately led to the use of a design plan and materials inadequate for supporting the loads acting on the box beam hanger connections. • The Hyatt Regency case drew immediate attention to the communication patterns followed by structural engineers and highlighted the problems that can result when poor or ambiguous communication leads to a misunderstanding of responsibilities • The case illustrates the dynamics of communication systems in the construction industry and illustrates the importance of greater awareness of role definition and communications networks in structural engineering • The dynamics of communication systems within the civil engineering profession as a whole are clearly illustrated by an analysis of the significant communication issues that the Hyatt Regency case highlights
The Importance of Role Definitions • Roles and corresponding responsibilities of structural engineers and steel fabricators are defined according to four basic categories of work involved in structural steel construction: • Fabrication • Erection • Materials • Engineering • In matters of engineering, there is often overlapping of responsibilities • In the Hyatt Regency case, overlapping responsibilities led to serious breaches in communication between these two team members—design engineers and steel fabricators—which led to construction of faulty walkways • In instances where engineer and fabricator can perform similar tasks, they clarify their duties through available formal and informal communication channels, which includes written and oral communication as well as precise and accurate structural and shop drawings
Roles and Responsibilities in Construction and Engineering • In the construction industry and civil engineering practice, a crucial distinction is made between “design” and “develop” in defining the steel fabricators role: • Design—Fabricator “designs” a connection if such work requires the steel fabricator to use “engineering judgment” to calculate loads and stresses • Develop—Fabricator “develops” connections by simply following the structural engineer’s instructions—by installing the necessary components and materials and consulting the American Institute of Steel Construction (AISC) Manual, but without any exercise of ‘engineering judgment such as calculation of loads. • It is the full responsibility of the structural/design engineer for defining the precise role the steel fabricator will play in the design or development of a connection • The structural engineer must communicate exact instructions to the fabricator through the structural design drawings • These instructions depend, in turn, • on a clear understanding of the type of connections the drawing depicts—Simple, Complex, or Special • On the nature of the design—whether it is Complete or Incomplete
Communication of Design Responsibility from Structural Engineer to Steel Fabricator Structural Engineer’s Section Detail Drawings Simple Type of Connection ? Complex or Special Connection Design Shown ? Yes No Extent of Connection Design ? Fabricator Has Design Responsibilities Complete Fabricator Has No Design Responsibilities Incomplete
Findings of the Deutsch Commission • In accord with Missouri law, the Missouri Licensing Board presented its case in front of the Administrative Law court to obtain permission to discipline the two engineers (Gillum and Duncan) • “…it is only upon a proper communication of the engineer’s desire or acquiescence that the fabricator perform a function or obligation of design.” -- Deutsch (1985) • During the hearings the design engineers argued that omission of any information on the structural drawings should alert the fabricator to design responsibility • This decision does not conform to the general “custom and practice” that has developed in structural engineering, governing assignment of design responsibility (simple v. complex or special connections) • “The determination of connection type and hence designation of design responsibility falls clearly within the parameters of the design engineer’s responsibilities.” –Deutsch (1985) • “Relying on a subordinate to detect unspoken intent and perform the omitted engineering calculations is not permissible.” – Deutsch (1985) • The structural engineer “bears the burden of communicating his [sic] intent to the contractor and assumes the risk of confusion or non-communication.” –Deutsch (1985) • “…The burden of and responsibility for clear communication lies with the engineer who assumes the risk of ambiguity in his [sic] design drawings.” – Deutsch (1985)
CAUSAL ANALYSIS OF THE DISASTER:ORGANIZATIONAL FACTORS CAUSES • On October 14, 1979, while the hotel was still under construction, more than 2700 square feet of the atrium roof collapsed because one of the roof connections at the north end of the atrium failed. • On October 20, 1979, G.C.E.'s Gillum wrote the owner, offering to undertake both an atrium collapse investigation as well as a thorough design check of all the members comprising the atrium roof. • The management called in an independent engineering firm, Seiden-Page, to find the cause behind the roof collapse.G.C.E. also investigated the roof collapse. • In order to save money, management neglected to have the rest of the building looked over. • During testimony, G.C.E. stated that on three separate occasions they requested on-site project representation to check all fabrication during the construction phase • However, these requests were not acted on by the owner (Crown Center Redevelopment Corporation), due to additional costs of providing on-site inspection. • The owner then declared the building safe after the investigation of the roof collapse.
HYATT REGENCY WALKWAY COLLAPSE:SOCIO-CULTURAL FACTORSRole of Regulatory Mechanisms • Failure of either design to meet Kansas City Building Codes • following the American Institute of Steel Construction (AISC) standards. • The KCBD dictates that the minimum value for the mean ultimate load capacity for beams such as those in the Hyatt should be 151 kN. • Based on test results, the mean ultimate capacity of the single-rod connection was approximately 91 kN, depending on the weld area. • Thus 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. • The second, modified and constructed design, therefore, only held 30% of the minimum weight put forth by Kansas City rules and regulations. • By mere calculations, the first design was obviously the more effective one even though it was faulty to begin with. • From the disastrous results, one can see the importance of having a design that is structurally sound
“Study Faults Kansas City Building Inspection.” The New York Times, 7 Sept., 1981: 29 • Experts at the International Conference of Building Officials (ICBO) conducted a lengthy, costly study of the Licensing and Inspection (L&I) practices of the Kansas City administers and inspectors • The study disclosed a number of deficiencies in the inspection procedures that were in effect when the walkways collapsed • It was discovered that the division of public works was not required to review all of the design changers • The study found that the city L&I codes administration division of the public works department “rarely requires” structural calculations for a project and did not review all the design changes.” • The ICBO summary report said that the Kansas City L&I lacked “the expertise” to keep up with its projects resulting from diminished funding and which led to hasty, neglectful instruction practices
Summary of Causal Analysis: Forensic Engineering Ethics • Structural Design Failure • Poor Management Communication • Mis-understandings in design modifications • Inadequate attempts to properly review facilities for safety purposes • Ineffective local and state regulatory system
LEGAL RAMIFICATIONS “Deutsch Commission” (1985): “Report of the Administrative Hearing Commission, State of Missouri, Case No. AR-84-0239, Missouri Board for Architects, Professional Engineers and Land Surveyors vs. Daniel Duncan, Jack Gillum, and GCE, Inc, Jefferson City, MO. While Kansas City did not convict the engineers of criminal negligence due to lack of evidence, the accident investigation concluded that G.C.E., in preparation of their structural detail drawings, "depicting the box beam hanger rod connection for the Hyatt atrium walkways, failed to conform to acceptable engineering practice. [This is based] upon evidence of a number of mistakes, errors, omissions and inadequacies contained on this section detail itself and of [G.C.E.'s] alleged failure to conform to the accepted custom and practice of engineering for proper communication of the engineer's design intent." Following the accident investigations, on February 3, 1984, the Missouri Board of Architects, Professional Engineers and Land Surveyors (MBAPELS) found Daniel M. Duncan, Jack D. Gillum, and G.C.E. Inc., guilty of: “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.”
LEGAL RAMIFICATIONS • Evidence showed that neither due care during the design phase, nor appropriate investigations following the atrium roof collapse were undertaken by G.C.E. • In addition, G.C.E. was found responsible for the change from a one-rod to a two-rod system. • Further, it was found that even if Havens failed to review the shop drawings or to specifically note the box beam hanger rod connections, the engineers were still responsible for the final check. • Evidence showed that G.C.E. engineers did not "spot check" the connection or the atrium roof collapse, and that they placed too much reliance on Havens. • As a result of the findings of the State as well as the MBAPELS, Duncan and Gillum lost their licenses to practice engineering in the State of Missouri (and later, Texas), and G.C.E. had its certificate of authority as an engineering firm revoked.
Statement from the Deutsch Commission • “There is no single procedure proscribed by the engineering profession for review and approval of shop drawings. The ultimate objective of any such shop drawing review procedure is to provide assurance that all structural engineering work performed by others on connections is done in accordance with acceptable engineering practice and that a qualified design professional has either performed such engineering work or reviewed such work prior to acceptance.” • “…Engineering and design work on such connections should be reviewed so as to determine that it is of such a quality as to assure the engineer of record that such work was actually and properly performed or thoroughly reviewed by himself or another professional engineer.”
PROFESSIONAL RESPONSIBILITY FOR SAFETY IN DESIGN • It is always important that an engineer puts the safety of the public above all else (“Paramountcy Clause”). G.C.E. failed to do this. • Violation of Due Care Principle • First of all, G.C.E.’s original and second design of the walkway failed to meet the requirements of the Kansas City Building Code 5 by not supporting the required 151kN. The investigation ruled that this reflected negligence by GCE. • By failing to meet building codes, G.C.E. also failed to put the public’s welfare above everything else. Their design did not adhere to the ASCE Engineering Code of Ethics. • The engineers failed to do a final check or even a “spot check”of their design. They neglected to check the safety and load capacity of the hanger connection to begin with. Then, when Havens did change the design from a single to a double hanger rod box beam connection, G.C.E. failed to look over the shop drawings one last time. • The engineers failed to put the public’s best interest first in this case.
Violations of Principles of Professionalism • Having and using appropriately sophisticated and theoretical knowledge • This was not adhered to when the engineers created and approved both the original as well as new designs • Serves the public good • This was a disaster!!—They never serve the public good • Organized by a special society or organization controlled by members who set industry standards an draft codes of ethics • The engineers involved have done their profession a great injustice by straying from top levels of technical competency and irresponsible behavior
Violation of ASCE Code of Ethics • “Engineers shall hold paramount the safety, health, and welfare of the pubic in the performance of their professional duties.” • Violated from the very design stage and onto the construction stage—the change rendered the structure hardly able to hold its own weight. • If the engineers were at all concerned with the potential risks the change would produce, the flawed design might not have been constructed • “Engineers shall issue public statements only in an objective and truthful manner.” • The attempts, by GCE, to accuse others of the faulty design and claiming the design change was not approved violated this code • “Engineers shall act in such a manner as to uphold and enhance the honor, integrity, and dignity of the engineering profession.” • The charge of “gross negligence, incompetence, misconduct and unprofessional conduct in the practice of engineering” greatly tarnished the dignity and respectability of the engineering profession • “Engineers shall not complete, sign, or seal plans and/or specifications that are not of a design safe to the public health and welfare and in conformity with accepted engineering standards.” • Routine computations should have revealed the inadequacy of the walkway supports • Violation of Standard of Care Principle • “Services performed in a manner consistent with that degree of care and skill ordinarily exercised by members of the same profession currently practicing under similar circumstances.”
VIOLATIONS OF CODES OF ETHICS • The Engineers in the case violated the following ASCE Codes, which obligate the engineer: • To accept responsibility in making engineering decisions consistent with the safety, health and welfare of the public • To disclose promptly factors that might endanger the public or the environment. • To seek, accept, and offer honest criticism of technical work, to acknowledge and correct errors, and to credit properly the contributions of others. • The engineering firm decided to make a change in the design of the ceiling support rods, but the public safety was not kept as a primary objective. • The design of the support rods were not thoroughly checked to see if the initial design, or the re-design, would comply with the Kansas City Building Code for maximum load capacity. • The design of the suspended walkway support system was altered so as to save money and time for the owner as well as for the contractors. • In actuality, both the revised and the initial designs for the support rods did not meet the safety standards. • Soon after the disaster, the ASCE formally adopted a statement that states structural engineers have full responsibility for design projects
ASCE Disciplinary Hearing • In 1985, the board of the ASCE found the Engineer of Record (EOR) vicariously responsible for error in shop the drawing process, but not guilty of gross negligence or unprofessional conduct • His membership was suspended for a period of 3 years • As a result of the Hyatt Regency Walkways Collapse, ASCE adopted a report that states structural engineers have full responsibility for design projects.
ETHICAL ANALYSIS OF THE CASE • The responsibility for, and obligation to, design steel-to-steel connections in construction and issues of negligence and an engineer’s design responsibilities lies at the heart of the Hyatt Regency Hotel project controversy. • A typology of Responsibility • The design engineers are at (moral) fault for improperly designing the rod and not checking the shop drawings to make sure they would adequately support the walkways. • The fabricators are at (moral) fault for not realizing that the design that they had modified and assembled would not be enough to hold up the walkways. • The owners of the hotel are at (moral) fault because on three separate occasions requests were made for on-site inspections that could have revealed the problem while it was still being built.
Responsibility of Design Engineers • Possible reasons for design engineer’s agreeing to the design change: • “fast-track” nature of the project—common-place practice in the construction industry to begin actual construction of a building before the design work is completed, primarily to avoid the effects of rising construction costs during the design and construction periods • saving time; • saving money; • avoiding a call for reanalysis, thereby raising the issue of a request to recheck all connector designs following the previous year's atrium roof collapse; • following his immediate supervisor's orders; • looking good professionally by simplifying the design; • misunderstanding the consequences of his actions; or • any combination of the above.
Responsibility of Design Engineers • When the engineer's actions are compared to professional responsibilities cited in the engineering codes of ethics, an abrogation of professional responsibilities by the engineer in charge is demonstrated. • The engineers at GCE had a professional obligation and duty to take into consideration the possibility that Havens Steel may have overlooked a problem with the design or design change • Due Care Principle • The process in which GCE revised and approved their drawings had to be deficient—if the design had gone through the required “process meetings,” the fatal flaw may have been detected and the disaster may have never occurred
Responsibility of Design Engineers • Drafting errors in transcribing the conceptual detail of the connection from the designer’s detail to the drawing • Checking errors by not verifying the detailed connections • Outside peer review, following the atrium collapse did not check shop drawings • In-house design check questions following the atrium collapse were not verified • The engineer relied on the fabricator to design the connection as well as all other steel-to-steel connections in the atrium (Was this the industry custom at the time?) • The fabricator transferred partially completed shop drawing details to an outside firm to complete • The firm assumed that the connection was the final design
Responsibility of Fabricators and Contractors • Design by fabricator judgment was motivated by: • Strict adherence to the structural drawings, • as prescribed by the AISI manual, • under the fabricator’s discretion. • The materials selected for the fabrication were standard strength, size, and grade of material, rather than what should have been used to compensate for the added stress of the altered design.
Responsibility of Crown Redevelopment Corporation • Failure to issue full on-site inspection of hotel construction after the collapse of the atrium roof months earlier