Topic 13: Ethics and Design by L587rDN

VIEWS: 21 PAGES: 24

									          Ethics in Engineering

Outline
  •Case Studies
     •Hyatt Regency Walkway Collapse
     •Hartford Civic Center Roof Collapse
Kansas City Hyatt
   Overview

                                         The Attrium




 The Hyatt Regency Hotel Today…




                                  …From Microsoft Live Maps
         Kansas City Hyatt Disaster
                Overview
The Event –
•   July 17, 1981, the Hyatt
    Regency Hotel in Kansas City,
    Missouri, held a dance party in
    their atrium lobby.

•    With party-goers standing and
    dancing on the suspended
    walkways, the second and
    fourth-floor story walkways
    across the atrium failed, and
    both walkways collapsed onto
    the crowded first-floor atrium
    below. The fourth-floor walkway              Kansas City Star
    collapsed onto the second-floor
    walkway, while the offset third-
    floor walkway remained intact.

                    …Information taken from Engineering.com and http://ethics.tamu.edu/ethics/hyatt/hyatt1.htm
   Kansas City Hyatt Disaster
          Overview
The Kansas City Hyatt Regency
walkways collapse left 114 dead and
in excess of 200 injured. In addition,
millions of dollars in costs resulted
from the collapse, and thousands of
lives were adversely affected.




                   Kansas City Star
                 Kansas City Hyatt
                         Who did What
• Over a year before the collapse, the design of the walkway hanger
  rod connections was changed in a series of events and
  communications (or disputed miscommunications) between the
  fabricator (Havens Steel Company) and the engineering design
  team (G.C.E. International, Inc., a professional engineering firm).

•    The fabricator changed the design from a one-rod to a two-rod
    system to simplify the assembly task, doubling the load on the
    connector, which ultimately resulted in the walkways collapse.
                Kansas City Hyatt
                         Who did What
• Second, the fabricator, claimed that his company (Havens)
  telephoned the engineering firm (G.C.E.) for change approval.
  G.C.E. denied ever receiving such a call from Havens. Though
  G.C.E. did put a stamp of approval on a later copy of the modified
  blueprints!

• Third, on October 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. In
  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.
                Kansas City Hyatt
                        Who did What
• Fourth, even as originally designed, the walkways were barely
  capable of holding up the expected load, and would have failed to
  meet the requirements of the Kansas City Building Code.
Kansas City Hyatt
 The Failure Analysis
Kansas City Hyatt
 The Failure Analysis
Kansas City Hyatt
 The Failure Analysis
Kansas City Hyatt
 The Failure Analysis
                  Kansas City Hyatt
                                     Details
Original design called for walkways that were each supported by three
crossbeams attached to three pairs of support rods from second floor to
ceiling…would have only supported 60% required by Kansas City Building
Code!
Havens Steel Company, the contractor responsible for manufacturing the rods,
objected to one threaded rod through the fourth floor since threads would be
ruined during installation…suggested the two rod design.

New design meant that instead of
each floor supporting it’s own
weight, the fourth floor walkway’s
crossbeams had to support itself
AND the second story walkway…
this design led to a configuration
that could support only 30%
required by Kansas City Building
Code!!
                 Kansas City Hyatt
                                Details
Also, the failures were compounded by the fact the nuts that were supporting
each crossbeam were situated directly under weld-joints in the boxbeams… the
weakest point in the structure!
                       Kansas City Hyatt
                                   Ethical Questions
•   ASME Code Of Ethics Of Engineers
•   The Fundamental Principles
     –   Engineers uphold and advance the integrity, honor, and dignity of the Engineering
         profession by:
•          I. using their knowledge and skill for the enhancement of human welfare;
•          II. being honest and impartial, and serving with fidelity the public, their
    employers and clients; and
•         III. striving to increase the competence and prestige of the engineering
    profession.
•   The Fundamental Canons
     –   Engineers shall hold paramount the safety, health and welfare of the public in the
         performance of their professional duties.
     –   Engineers shall perform services only in areas of their competence.
     –   Engineers shall continue their professional development throughout their careers and shall
         provide opportunities for the professional development of those engineers under their
         supervision.
     –   Engineers shall act in professional matters for each employer or client as faithful agents or
         trustees, and shall avoid conflicts of interest.
     –   Engineers shall build their professional reputation on the merit of their services and shall not
         compete unfairly with others.
     –   Engineers shall associate only with reputable persons or organizations.
     –   Engineers shall issue public statements only in an objective and truthful manner.
                 Kansas City Hyatt
                          Ethical Questions

Ethical Questions –

       Who is ultimately responsible for checking the safety of final designs
  as depicted in shop drawings?


  …When we take the implicit social contract between engineers and
  society, the issue of public risk and informed consent, and codes of
  ethics of professional societies into account, it seems clear that the
  engineer must assume this responsibility when any change in
  design involving public safety carries a licensed engineer's seal.
                        Kansas City Hyatt
                                   Ethical Questions
Ethical Questions –
In terms of meeting building codes, what are the responsibilities of the engineer? The fabricator? The
     owner?

If we assume the engineer in the Hyatt case received the fabricator's telephone call requesting a
     verbal approval of the design change for simplifying assembly, what would make him approve
     such an untenable change?

Some possible reasons include:
•  saving time;
•  saving money;
•  avoiding a call for re-analysis, 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.

All these pave the way for legitimate charges of negligence, incompetence, misconduct and
     unprofessional conduct in the practice of engineering.
           Kansas City Hyatt
                Ethical Questions

Other Ethical Questions –
What about the owner, or fabricator??



What if the call was not made? While
 responsibility rests with the fabricator for
 violating building codes, would the
 engineers involved in the case be off the
 hook? Why or why not?
The Hartford Civic Center
       Collapse




     …text from ‘Hartford Civic Center Arena Roof Collapse’ by Rachel Martin
http://www.eng.uab.edu/cee/faculty/ndelatte/case_studies_project/Hartford%20Civic%20Center/hartford.htm
The Hartford Civic Center
       Collapse
              On January 18, 1978 the Hartford
            Arena experienced the largest
            snowstorm of its five-year life. At 4:15
            A.M. with a loud crack the center of the
            arena's roof plummeted the 83-feet to
            the floor of the arena throwing the
            corners into the air. Just hours earlier
            the arena had been packed for a
            hockey game. Luckily it was empty by
            the time of the collapse, and no one
            was hurt (Ross, 1984).
      The Hartford Civic Center
  Collapse – Construction Concerns
 To save time and money, the roof frame was completely assembled on the ground.
  While it was still on the ground the inspection agency notified the engineers that it had found
excessive deflections in some of the nodes. Nothing was done. After the frame was completed,
hydraulic jacks located on top of the four pylons slowly lifted it into position.
  Once the frame was in its final position but before the roof deck was installed, its deflection was
measured to be twice that predicted by computer analysis, and the engineers were notified. They,
however, expressed no concern and responded that such discrepancies between the actual and the
theoretical should be expected (Levy and Salvadori, 1992).
    When the subcontractor began fitting the steel frame supports for fascia panels on the outside of
the truss he ran into great difficulties due to the excessive deflections of the frame. Upon notification of
this problem, the general contractor "directed the subcontractor to deal with the problem or be
responsible for delays." As a result the subcontractor coped some of the supports and refabricated
others in order to make the panels fit, and construction continued (ENR, April 6, 1978).
   The roof was completed on January 16, 1973 (Feld and Carper, 1997). The next year, a citizen
expressed concern to the engineers concerning the large downward deflection he noticed in the arena
roof, which he believed to be unsafe. The engineers and the contractor once again assured the city
that everything was fine (Levy and Salvadori, 1992).
            The Hartford Civic Center
           Collapse – Failure Analysis
•   LZA (hired by Hartford to investigate the collapse) discovered that the roof began failing as soon
    as it was completed due to design deficiencies. A photograph taken during construction showed
    obvious bowing in two of the members in the top layer. Three major design errors coupled with the
    underestimation of the dead load by 20% (estimated frame weight = 18 psf, actual frame weight =
    23 psf) allowed the weight of the accumulated snow to collapse the roof (ENR, April 6, 1978). The
    load on the day of collapse was 66-73 psf, while the arena should have had a design capacity of
    at least 140 psf (ENR, June 22, 1978). The three design errors responsible for the collapse are
    listed below.
•   The top layer's exterior compression members on the east and the west faces were overloaded by
    852%.
•   The top layer's exterior compression members on the north and the south faces were overloaded
    by 213%.
•   The top layer's interior compression members in the east-west direction were overloaded by 72%.
•   In addition to these errors in the original design, LZA discovered that the midpoint braces for the
    rods in the top layer had not been installed. The exterior rods were only braced every 30-feet,
    rather than the 15-feet intervals specified, and the interior rods were only partially and
    insufficiently braced at their midpoints. This significantly reduced the load that the roof could
    safely carry. The table on the next slide compares some of original details to actual designs used
    in the building, demonstrating the reduction in strength that these changes caused. Connection A
    was typically used on the east-west edges of the roof, while connection B was used on the north-
    south edges. Most of the interior bars used connection C, while a few used connection D. The
    key difference between the original and the as-built details is that the diagonal members were
    attached some distance below the horizontal members, and thus were unable to brace the
    horizontal members against buckling.
 The Hartford Civic Center
Collapse – Failure Analysis
 The Hartford Civic Center
Collapse – Failure Analysis
        The Hartford Civic Center
       Collapse – Ethical Questions
Ethical Questions:

   Multiple subcontractors without an overseeing structural engineer left the project
with the construction manager to determine what to do with a sagging roof!

   The excessive deflections apparent during construction were brought to the
engineer's attention multiple times. The engineer, confident in his design and the
computer analysis which confirmed it, ignored these warnings and did not take the
time to recheck its work. An ethical engineer would pay close attention to
unexpected deformations and investigate their causes. They often indicate
structural deficiencies and should be investigated and corrected immediately.
Unexpected deformations provide a clear signal that the structural behavior is
different from that anticipated by the designer. Also this collapse raises the
important question of whether the factor of safety should be increased for
buildings with high occupancy. Should the impact of a possible failure be taken
into account in determining the factor of safety (Kaminetzky, 1991)?

								
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