| The
National Construction Safety Team Advisory Committee
National
Institute of Standards and Technology
Minutes
of October 19 - 20, 2004, Meeting - Gaithersburg, Maryland
The
slides from the presentations are embedded as links to PDF files
within this document and, thus, are summarized in these minutes.
Each presentation was followed by a discussion period. “Q”
indicates a question, “A” the corresponding answer,
and “C” a comment. All questions and comments, unless
otherwise noted, were made by Advisory Committee members. All
answers, unless otherwise noted, were by NIST personnel.
The
minutes summarize the main points of each discussion; they are
not intended to be a verbatim transcript of the meeting.
October
19,
2004
Back
to agenda
Opening
Remarks
Dr. Robert Hanson, Acting Committee Chairman
Dr. Robert Hanson, acting chairman for the fifth meeting of
the National Construction Safety Team (NCST) Advisory Committee,
called the meeting to order. Mr. Paul Fitzgerald and Dr. Kathleen
Tierney were unable to attend this meeting due to prior commitments.
Dr. Hanson reviewed the process and rules of the meeting, stating
that public observers may only participate during the public
comment session at the end of the first day. He also reminded
the Committee members of the procedures for approving and disapproving
recommendations and actions. Dr. Hanson then turned the meeting
over to Dr. James Hill, Director of the Building and Fire Research
Laboratory at the National Institute of Standards and Technology
(NIST), for his opening remarks.
Opening Remarks
Dr. James Hill, Director, Building and Fire Research Laboratory
Dr. Hill welcomed the Committee and the public attendees to
the meeting. Dr. Hill noted that Dr. Hratch Semerjian, the
Acting Director of NIST, and Dr. Richard Kayser, the Acting
Deputy Director, were unable to attend this meeting of the
NCST Advisory Committee. However, Mr. Matthew Heyman, NIST
Chief of Staff, was in attendance and was the Acting Director
of NIST in their absence.
Dr. Hill stated his appreciation for the commitment and dedication
of the NCST Advisory Committee members. He apologized for the
change in the dates for this meeting and noted that the change
to an open session for most of the meeting necessitated the
change in schedule.
Dr. Hill reminded
the Committee that the purpose of this meeting was to review
the technical progress on the World Trade Center
(WTC) and Rhode Island Station nightclub investigations, to
review the issues that have been identified as a result of
these investigations, and to get the Advisory Committee’s
feedback on these issues. Dr. Hill also noted that NIST would
like to get input from the Advisory Committee on the format
of the next meeting, scheduled for November.
With respect to
the Committee’s report to Congress,
Dr. Hill noted that NIST has discussed not taking on further
investigations without resources.
Dr. Hill stated that Hurricane Charley did a great deal of
damage in Florida. NIST worked with teams from the Federal
Emergency Management Agency (FEMA), the Institute for Business
and Home Safety (IBHS), and Texas Tech University that were
deployed following the hurricane and forwarded an assessment
of damage and failures that would merit further investigation
to the director of NIST. The Department of Commerce asked what
NIST could do in response to Hurricane Charley. NIST responded
by saying that it could conduct a study of specific building
failures. He informed the Committee that many of the criteria
in the NCST act for initiating an investigation were met for
Hurricane Charley. The Department of Commerce negotiated with
the Office of Management and Budget, and there is a possibility
that funds may be made available through supplemental appropriation
to FEMA, although a final decision has not been made.
C: The reason for creating the NCST was for timely response
to building disasters, and whatever we can do as the Advisory
Committee to put pressure on appropriate entities to fund NIST
is important. To conduct investigations 6 to 9 months after
an event is not appropriate. The money came through FEMA before,
and it should come directly to NIST.
C: It’s an item we’ll include on the agenda for
the session on what our report to Congress should include.
Back to agenda
Status of the World Trade Center Investigation and Discussion
Dr. S. Shyam Sunder, Acting Deputy Director, Building and Fire
Research Laboratory
PRESENTATION (pdf file)
Dr. Sunder, the Lead Investigator, gave an update of the WTC
Investigation. He said that good solid technical progress continues
to be made on the investigation, drawing talent from NIST,
outside experts, and contractors. He noted that the Investigation
is ongoing and that current findings may be revised and additional
findings presented in the final report. NIST is not making
any recommendations at this time; all recommendations will
be made in the final report.
Dr. Sunder said that most technical work is complete; NIST
plans to release a draft of the final report for public comment
in December 2004 or January 2005. NIST plans to release the
final investigation report in April or May 2005. The WTC 7
report will be issued as a supplement to the main report, with
a draft issued in May and the final in July 2005. The report
hierarchy includes the main WTC Investigation Report, supported
by eight Program Reports, which in turn are supported by about
30 technical topic reports.
Dr. Sunder described the investigation objectives and some
specific questions that NIST is seeking to answer. He also
described the context of the findings and noted that the findings
being presented to the Committee were not yet final. Dr. Sunder
then described the analysis method used to determine the probable
collapse sequence. He described the leading hypotheses for
collapses of WTC 1 and WTC 2, which identify the specific damage
scenarios and load redistribution paths for each tower. Both
hypotheses involve (1) damage to the building support columns,
floor framing, and fireproofing due to the aircraft impacts;
(2) subsequent fires that softened the steel core and perimeter
support columns; (3) buckling of support columns; and (4) global
collapse. The leading collapse hypotheses will continue to
be refined until the analyses are complete.
Dr. Sunder described
the aircraft impact analysis and how NIST determined the
extent of the damage to support columns,
floors, and fireproofing. He summarized the findings of this
analysis by stating that (1) the robustness of the perimeter
frame-tube system and large dimensional size of the WTC towers
helped the buildings withstand the aircraft impact; (2) the
WTC towers displayed significant reserve capacity immediately
after aircraft impact; (3) the loads from the damaged and severed
columns were carried by nearby undamaged columns; (4) the towers
would have continued to remain standing indefinitely, but for
another significant event—the subsequent fires.
Dr. Sunder then reviewed the fire modeling performed for the
WTC Investigation and showed a number of simulations. He noted
that the fires played a major role in further reducing the
structural capacity of the buildings, initiating collapse.
He also stated that the jet fuel that ignited the fires was
mostly consumed within the first few minutes after impact and
that the fires were mainly due to burning the building contents,
and to a lesser extent, aircraft contents.
Dr. Sunder noted
that the time delay between collapses of the WTC towers was
primarily due to: (1) the asymmetric structural
damage caused by aircraft impact to WTC 2 compared to WTC 1;
(2) the time it took for heat to soften and buckle the core
columns that had fireproofing dislodged by debris impact; (3)
the structures’ ability to redistribute loads as the
core columns shortened; (4) the time it took for the fires
to migrate through the buildings; and (5) the time it took
to heat, soften, and buckle the perimeter columns.
Dr. Sunder then described the fire resistance testing of the
floor system performed at Underwriters Laboratories. In summarizing
the tests, he stated that the test structures were able to
withstand fire conditions for between 45 minutes and 2 hours.
The 45 minute fire resistance for the standard 17 foot floor
system with a specified 0.5 inch fireproofing did not meet
the 2 hour requirement of the 1968 New York City Building Code.
The 2 hour fire resistance for the standard 17 foot floor system
with the as-applied 0.75 inch fireproofing met the 2 hour requirement
of the 1968 New York City Building Code. The likely cause of
the difference in results is not the fireproofing thickness
on the trusses themselves, but the presence or lack of fireproofing
on the undersides of the metal deck.
Dr. Sunder summarized the analyses performed on steel recovered
from the collapsed WTC towers. He noted that the 236 pieces
of steel collected by NIST were adequate for determining the
quality and properties of steel for the Investigation. Approximately
87 percent of the tested steel specimens exceeded the required
minimum yield strengths. The safety of the WTC towers was most
likely not affected by the fraction of steel that, according
to NIST testing, did not meet the required minimum yield strength.
He described the NIST review of wind tunnel testing of the
WTC towers that included the original WTC design wind loads,
the state-of-the-practice wind tunnel studies conducted by
independent private sector laboratories in 2002, and the wind
load estimates developed by NIST. Dr. Sunder noted that the
original design wind loads on the towers exceeded those established
by the New York City Building Code. On September 11, 2001,
the towers were subjected to in-service live loads that are
considered to be approximately 25 percent of the design live
loads. The wind loads on that day were minimal, thus allowing
significantly more reserve capacity for the exterior walls.
The safety of the WTC towers was most likely not affected by
the fraction of members for which the demand exceeded capacity
under the original design wind loads.
Dr. Sunder described
NIST’s current findings related
to evacuation and emergency response. He described the interviews
conducted with more than 1,000 surviving occupants and the
results of NIST’s decedent analysis. He noted that approximately
87 percent of the WTC tower occupants were able to evacuate
successfully, including more than 99 percent below the floors
of impact. Occupants were often unprepared for the physical
challenge of building evacuation. Despite perceptions of some
occupants, counterflow was found to not be a significant factor
in the total evacuation time when compared to other factors.
Based on existing egress models and actual evacuation times
on September 11, 2001, it is estimated that a full building
evacuation of each WTC tower with 25,000 people, three times
the number present on September 11, would have required about
4 hours.
He noted that emergency responders were implementing three
different operational strategies and that none of the more
than 100 first responders interviewed by NIST thought that
the WTC towers would collapse. Dr. Sunder stated that situational
awareness varied from adequate for those outside the buildings
that could see what was going on, to poor for those inside
the buildings that could not see what was happening and that
had poor radio communications.
All three responding departments (New York City Fire and Police
Departments and the Port Authority of New York and New Jersey
Police Department) experienced difficulties with radio communications.
Two basic issues were function of the radio equipment in high-rise
environments and the volume of radio traffic. Roughly one-third
to one-half of the radio messages transmitted during the radio
traffic surge conditions was not complete or understandable.
Dr. Sunder noted that first responders did not have adequate
information on, nor an overall perspective of, the conditions
in the WTC towers and what was happening elsewhere at the WTC
site, and that interagency information sharing was inadequate.
A significant amount of evidence (first-person interviews,
reports, and photographic data) shows that the different agencies
were working together during the WTC disaster). Interagency
operations were detrimentally affected with the loss of the
Office of Emergency Management command center that was located
inside WTC 7. First responder interviews suggest that interagency
competition had minimal effect on operations at the WTC complex
on the morning of September 11, 2001. The data also suggest
that some of the problems experienced were due to personnel
not understanding the operating practices of the other agencies
The smoke management systems in the WTC towers were not activated
during the fires on September 11, 2001. The likelihood of these
systems being functional was very low due to the damage inflicted
by the aircraft. Disruption of the heating, ventilating, and
air conditioning (HVAC) system by the aircraft impact created
a major path for vertical smoke spread in the buildings.
Dr. Sunder discussed the applicability of building codes.
Although not required to conform to the New York City Building
Code, the Port Authority of New York and New Jersey (Port Authority)
elected to adopt the provisions of the 1968 code more than
3 years before it went into effect. The 1968 code had less
restrictive provisions compared with the 1938 code. The Port
Authority was created as an interstate entity under a clause
of the U.S. Constitution permitting compacts between states
and is not governed by the building and fire codes of any local,
state, or federal jurisdiction. He then cited several documents
that provide the rationale the Port Authority used for choosing
the 1968 New York City Building Code.
Dr. Sunder noted
that NIST does not set building codes and standards, but
provides technical support to the private sector
and other government agencies in the development of U.S. building
and fire practice, standards, and codes. He reviewed NIST’s
approach to making recommendations, stating that NIST has not
yet formulated recommendations. Dr. Sunder reviewed the issues
that have been identified by NIST. These issues are grouped
under the following major categories: (1) increased structural
integrity, (2) enhanced fire resistance, (3) improved building
evacuation, and (4) improved emergency response. In its final
report, NIST will recommend appropriate improvements in the
way buildings are designed, constructed, maintained, and used.
NIST will hold a conference in June 2005 to reinforce the importance
of its findings and recommendations from the Investigation
and encourage their implementation in practice.
Q: Referring to the column shortening in WTC 1, is the elastic
strain reported at room temperature?
A: No. The values reported are for elevated temperature. The
history is traced, including degradation of properties.
Q: For test 1 of the fire resistance tests of the floor systems
at Underwriters Laboratories, you show unrestrained rating
of one hour. Was that an analytical conclusion or a tested
result?
A: We show in each case an unrestrained rating when we actually
did a restrained test. What we are showing there is not the
result of an actual unrestrained test, but the temperature
criteria in the standard for a restrained test.
C: Right, one of the major significances of the series of these
tests is that test 2 was an unrestrained test and showed superior
performance.
Q: I want to ask about the floor performance. The way I understood
your description of the collapse scenario, the behavior of
the floor systems was not a central issue. Can you connect
the floor results with that?
A: The results reinforce each other. The results of the fire
test versus the load test support the finding that the floors
were not a driving force in the collapse.
Q: Do we know for the pieces of steel that did not meet the
requirement [referring to yield strength] what temperature
they reached?
A: Indications are that the metal we tested did not see any
kind of high-temperature excursions, and there was no damage
to the paint on those pieces. They did not get above 250 ºC.
Q: The web is usually the strongest part of a column. I am
puzzled by a data point on your slide showing the web of the
columns lower than specified. What was the value of the flange?
A: I will address that in my presentation tomorrow.
Q: Do the 27 emergency
responders from WTC 1 interviewed refer specifically to those
people themselves as opposed to people
that they know, other people that didn’t survive?
A: Yes, that is correct.
C
(NIST): We have brought fire and structural communities
together and developed models to analyze fire-structural interaction.
We will need to make the models more robust before the private
sector can adopt them for routine practice.
Back to agenda
Project
2 – Baseline
Structural Performance and Aircraft Impact Damage Analysis
Dr. Fahim Sadek, WTC Investigation, Project 2 Leader
PRESENTATION (pdf file)
Dr. Sadek gave an update of progress on the portion of the
WTC Investigation related to baseline performance and aircraft
impact damage. He described the development of the structural
models of the WTC towers and results of the baseline performance
analysis under design loading conditions (i.e., gravity and
wind).
He described the NIST review of wind tunnel testing of the
WTC towers that included the original WTC design wind loads,
the state-of-the-practice wind tunnel studies as provided by
CPP (Cermak Peterka Peterson, Inc.) and RWDI (Rowan Williams
Davis and Irwin, Inc.) for insurance litigation, and the wind
load estimates developed by NIST. Wind loads developed by NIST
were based on a critical assessment of information obtained
from CPP and RWDI reports and state-of-the-art considerations
in wind engineering.
He noted that the original design wind loads on the towers
exceeded those established by the New York City Building Code.
On September 11, 2001, the towers were subjected to in-service
live loads, which are considered to be approximately 25 percent
of the design live loads. The wind loads were minimal on that
day, thus allowing significantly more reserve capacity for
the exterior walls. The safety of the WTC towers was most likely
not affected by the fraction of members for which the demand
exceeded capacity under the original design wind load conditions.
Dr. Sadek
then described the aircraft impact analysis and how NIST
determined the extent of the damage to support columns,
floors, and fireproofing, and the distribution of aircraft
debris and fuel. He compared the NIST analysis with that performed
by MIT and Weidlinger, noting that the NIST results compared
well with the MIT analysis, but not as well with the Weidlinger
analysis, which over predicted aircraft damage to the towers.
A stability analysis by Weidlinger showed that the building,
with their estimated damage, would have collapsed immediately
after aircraft impact.
He summarized the findings for each area of analysis. The
original design wind loads on the towers exceeded those established
by the New York City Building Code and were higher than those
required by other selected building codes of the era. Estimated
wind loads vary by as much as 40 percent between two wind tunnel/climatological
studies conducted in 2002 by CPP and RWDI as part of insurance
litigation.
Dr. Sadek stated that the Demand/Capacity ratios estimated
from the original design case are, in general, close to those
obtained from a lower bound state-of-the-practice case. For
both loading cases, a small fraction of structural components
had Demand/Capacity ratios larger than 1.0; the safety of the
WTC towers was most likely not affected by this.
He noted relevant issues for future investigation including
(1) availability of standards for conducting wind tunnel tests
and for methods to estimate wind effects from test results
for design purposes, (2) availability of protocols for selection
of site-specific wind speed and directionality, and (3) adequacy
of prescriptive wind load standards for very tall buildings.
Q: How is capacity defined? [referring to the Demand/Capacity
ratios for the structural component estimates].
A: Capacity is defined by using the American Institute of Steel
Construction (AISC) Allowable Stress Design procedure.
Q: What material properties are used?
A: We are using specified or nominal design values for steel
properties.
Q: What changes
were made to the baseline design based on peer review by
Skidmore, Owings & Merrill?
A: NIST and Skidmore, Owings & Merrill reviewed the structural
database and corrected discrepancies. For the models, the exterior
wall modeling and connections of the floors to the exterior
walls were of concern. These were corrected. LERA (Leslie Robertson & Associates)
also responded to comments from Skidmore, Owings & Merrill
on the report, although there were not many comments on report
content.
Q: NIST combined data from two wind tunnel tests to prepare
their state-of-the-art wind load estimate. What input data
were needed for the state-of-the-art case?
A: Data from CPP and RWDI were hard to review. We had to develop
questions for each in order to understand what was done. After
getting data, we checked data from the National Oceanic and
Atmospheric Administration (NOAA) and found discrepancies.
Q: What is needed for the state-of-the-art case? What data
is needed? Can it be done without other data? What is unique?
A: There are a series of state-of-the-art considerations that
result in the NIST estimate of the design wind loads. Hurricane
wind profiles are assumed to be flat; that is not the case.
RWDI and CPP approaches both assume relatively flat hurricane
wind profiles. There are significant differences to account
for wind directionality and load combinations. RWDI and CPP
use significantly different approaches – one uses the
up-crossing method, and the other the sector-by-sector approach.
There is no specific guidance on how to integrate climatological
data to estimate site specific directional wind speeds.
A: Shyam’s explanation is clear. There were some constraints
on the state-of-the-art case; for example, we did not have
an independent wind tunnel test. We relied on the reports and
formal questions. CPP did not respond to our questions; RWDI
did. Both assumed flat hurricane wind speeds. A letter from
the University of Western Ontario justifying the use of flat
profiles has not yet been received by NIST. We identified errors
and inaccuracies in their results. State-of-the-art results
are closer to the physical realities.
A: RWDI and CPP are developing a white paper to address these
issues.
Q: I am interested
in what we know about matching the results of the impact
simulations to observations—for example,
the landing gear gets hung up in the core in the building in
the simulation. Do you have an explanation for that?
A: We were hoping to match that. This was a very chaotic event.
There are a number of uncertainties regarding the interior
layout, especially for WTC 2, and the location of debris masses
in the building. We assume there was a large mass somewhere
inside the building that deflected the landing gear. It may
be possible to simulate with additional runs and by changing
parameters; we could possibly get the landing gear to exit.
Q: What about the engine that passed through the building?
A: For WTC 2, we were able to get the engine to exit the corner
in the simulation. In order to get the engine to land at its
actual location, we also calculated the exit velocity to be
about 120 miles per hour. For the realistic case, the speed
by which the engine exited was about 80 miles per hour, and
for the plus case, the speed was getting close to 200 miles
per hour. This was also chaotic behavior, and the engine may
have been spinning with propulsion, so the 80 miles per hour
may make sense.
Q: How many more columns could be removed and the buildings
still stand?
A: When we did our preliminary stability analysis for WTC 1,
we removed up to eight columns from the core in the model,
and the building remained standing.
Q: There are uncertainties in these calculations. You can’t
see inside the buildings. Could more core columns have been
broken in WTC 1 than WTC 2? Or could none have been severed?
Are they definite impossibilities?
A: We tried to use parameters in the model in the best way
that we know them. We spent a lot of time to model the geometry,
material properties, and the failure criteria correctly. We
understand that these are subjected to uncertainties and tried
to bound the case. We are trying to complete additional studies
to confirm our model results.
C: This project has done a lot of excellent work. You and
your team should be congratulated. You need to be clear about
uncertainties in your report. I am concerned that there will
not be any technical topic reports for this project. I recommend
that technical topic reports be included for Project 2.
A: I agree. My thinking was that it would be hard to write
a concise report referring to topic reports. I felt that the
logic would be better in one large report with all the details
together.
C: Would you consider putting the detail into appendixes attached
to the report?
C: John’s comments are worthy of consideration. The Committee
will look hard at the way this report is being put together.
C: We can see the critical importance of the lack of physical
evidence to back up what is going on. I want to make this point
for future investigations.
Back to agenda
Project
5 – Simulation
of the Fires in WTC 1 and 2
Dr. Kevin B. McGrattan, WTC Investigation, Project 5, Mathematician
PRESENTATION
(pdf file)
Dr. McGrattan presented the results of fire simulations of
WTC 1 and WTC 2 performed with the NIST Fire Dynamics Simulator
(FDS). He explained the major trends in fire movement and temperature
on the various floors, and how these trends were validated
by visual observations. He discussed the sensitivity analysis
performed to determine how the results of the calculations
changed as a consequence of varying the major input parameters.
It was concluded that the fires in WTC 1, which could generally
be characterized as oxygen-limited or ventilation-controlled,
were less sensitive to changes in the fuel and combustible
loadings, compared to the fires in WTC 2, which could be characterized
as fuel-limited or fuel-controlled.
Q: Were the soffit conditions the same in both the realistic
and most severe cases?
A: Yes. We felt that it made more sense to leave the soffits
in the model.
Q: Aluminum burns well. Heat transfer for aluminum is five
to ten times higher than steel. Was aluminum combustion considered
in the model?
A: No. There are a number of issues and limitations in the
model. We increased the fuel load of wood and plastic in areas
where the aircraft was, but did not explicitly account for
aluminum.
Q: It is likely that the aircraft impact removed floors. Did
you account for double height floors?
A: Yes. We got data from the impact analysis.
Q: Did you vary the mesh size of the model?
A: In the beginning, we tested finer meshes for the single
floor calculations, but we concluded that there was not much
difference in the results.
C: You could do additional sensitivity studies with wider
variations. There are lots of unknowns, for example, the fuel
loads.
A: For 2 years prior to June 2004, we did orthogonal factorial
design. We then chose a handful of parameters for the final
work done since June. We wanted the less and more severe cases
to be in the ballpark with a realistic case. Everybody was
to choose three cases for each tower.
A: Kevin’s work was not the rate limiting step. The output
of his calculations has to be run through the ANSYS calculation,
and the feedback is quite long.
Q: You had a good
grip on partitions, fuel load, and ventilation for WTC 1.
There is a big difference in WTC 2 in the number
of windows open at time zero. Do you have a case where you’re
not ventilation-controlled?
A: In general, the fire in WTC 2 was not ventilation-controlled.
There were enough broken windows to provide air to the fires.
The bigger issue was the location and condition of the furnishings
after the airplane impact. The fuel (e.g., office furnishings
and aircraft debris) was redistributed by the aircraft impact.
It is difficult to model rubble. Virgin furnishings are well
understood. When the fire is not oxygen-limited, it is difficult
to model, and the fire in WTC 2 was not oxygen-limited.
Back to agenda
Project
5 – Simulating
the Coupled Fire, Thermal, Structural Response of the WTC
Towers
Dr. Kuldeep R. Prasad, WTC Investigation, Project 5, Engineer
PRESENTATION (pdf file)
Dr. Prasad described the development of the NIST Fire Structure
Interface (FSI), a software tool for coupling the Fire Dynamics
Simulator with the thermal and structural response of complex
building assemblies. A detailed algorithm was presented, based
on plane layer analysis for predicting the radiative flux boundary
condition to sub-grid scale structural elements. Finite element
models were constructed to predict the thermal response of
the perimeter and core columns, concrete slabs, and truss assemblies.
Structural damage and fireproofing damage caused by the aircraft
impact on the towers was incorporated in the models.
The software tool
was used to estimate the global thermal response of WTC 1
and WTC 2 under two scenarios (realistic
and severe). Dr. Prasad explained that numerical simulations
indicate the core column temperature is a strong function of
the state of the fireproofing as well as the geometry and location
of the column. Several core columns in WTC 1 reached a temperature
above 700 °C. The maximum temperature of an undamaged perimeter
column was between 250 °C and 350 °C. He pointed out
that fireproofing thickness and its variability were identified
as the single most important parameter that has a direct effect
on steel temperature.
Q: When the temperature
of a core column reached 700 ºC,
did you eliminate it from the model?
A: No. The analysis predicts the temperature history. For the
visualization, it was assumed that above 700 °C, the column
loses its load carrying capacity, and it does not regain its
load carrying capacity when it cools down.
Q: On the next to last slide for WTC 1, the fire is moving
around the core columns, but they still look cool.
A: The fireproofing on these core columns is not damaged in
this region. So, although there is fire activity in this region,
the steel columns have not heated significantly. Heavy columns
heat slowly. Variation in fireproofing thickness and the size
of the columns play a significant role.
Q: So the significance of the fireproofing if you look at that
slide with 5400 seconds is that some columns did not go above
150 °C?
A: Not necessarily. As the fires move away, the columns cool
down. What you’re observing is that the core columns
start to cool in the later stage.
Q: Do you make a blanket assumption that if the truss or column
is in the path of the airplane debris, then all the fireproofing
was knocked off?
A: We looked at the degree of damage. The partition walls have
a nominal strength of 500 pounds per square inch, and the fireproofing
has a cohesive and/or adhesive strength of about 2 pounds per
square inch. If the partitions were destroyed or knocked out
of the way, then it was assumed that the fireproofing would
be knocked off the column.
Q: What about the exterior columns—were they wiped clean
of spray-on fireproofing?
A: The same rules applied. We looked at the degree of damage
on the interior face.
Q: What about the fireproofing on the exterior of an exterior
column?
A: It remains intact.
Q: So in some cases you took off just one face of fireproofing?
A: Yes.
Q: WTC 2 had 0.5 inch of spray-on fireproofing. In WTC 1,
it was upgraded. It suggests that at first glance the fireproofing
on floors is a significant factor.
A: The WTC 2 floor trusses do heat more quickly. As Shyam described,
the loss of fireproofing is responsible for floor sagging,
and was a secondary effect.
A: In WTC 1 on the south side, the pulling in of the exterior
columns is due to core column shortening. In WTC 2, sagging
of the floors was significant.
A: The removal of fireproofing during impact was more important
than differences in initial thickness of fireproofing. To just
have floor failure induce global collapse, a large number of
floors would have to fail to cause collapse.
Q: The analysis converts Fire Dynamics Simulator (FDS) to
a two-zone description. Would you consider using a zone analysis
rather than FDS? To what extent would a zone analysis be useful?
A: Locally, a two-zone analysis is valid. We can not assume
constant temperatures over the entire floor.
Q: Is there any
illustration of where the fireproofing was in-place after
impact? NIST needs to illustrate that and the
thicknesses. With the floors in a secondary role, it will be
important to illustrate clearly in the final report. You mentioned
2.2 inch thickness—is that correct?
A: We presented in June that we assumed the fireproofing was
2.2 inches thick in WTC 1 as estimated from the average installed
plus the variability of measured thicknesses. We will make
every effort to graphically depict where the fireproofing was
intact and where it was dislodged.
Back to agenda
Project
5 – Reconstruction
of the Fires in the WTC Towers
Dr. Richard G. Gann, WTC Investigation, Project 5 Leader
PRESENTATION (pdf file)
Dr. Gann summarized the findings and issues related to reconstruction
of the fires in the WTC towers. The objective of Project 5
was to reconstruct the time-evolving temperature, thermal radiation,
and smoke fields in WTC 1, 2, and 7 for use in evaluating the
behavior and fate of occupants and responders and the structural
performance of the buildings.
Findings to date include the following: (1) loading of building
combustibles was on the light side of typical, (2) the movement
of the fires was complex and varied from floor to floor of
each building, (3) the FDS and FSI models can be used with
confidence to recreate the thermal effect of a given WTC fire
event, (4) both FDS and the photographic evidence indicate
that the dwell time of the fires was approximately 20 minutes,
and (5) FSI simulations show high sensitivity of structural
element temperatures to the presence or absence of spray-applied
fire resistant materials.
Issues include (1) the need for predictive tools for design-based
fire scenarios; and (2) the availability of standards and codes,
methodology, analytical design tools, and practical design
guidance to permit considering fire as a design condition for
the structure as a whole system.
Q: Ceiling tiles
were removed on the floors of impact—were
they removed from other floors?
A: Ceiling tile damage was observed throughout the buildings.
A: From the interviews, it was pretty well reported that ceiling
tiles were down throughout the building.
Back to agenda
Project
6 – Standard
Fire Tests of WTC Tower Typical Floor System
Dr. John L. Gross, WTC Investigation, Project 6 Co-Leader
PRESENTATION (pdf file)
Dr. Gross summarized the standard fire test of typical WTC
tower floor systems performed at Underwriters Laboratories.
The purposes of these tests were to (1) establish baseline
performance of the floor systems as they were originally built,
(2) differentiate the factors that most influenced the collapse
of the WTC towers, and (3) study the procedures and practices
used to accept an innovative structural and fireproofing system.
Tested floor systems included 17 foot and 35 foot spans with
0.5 inch or 0.75 inch of fireproofing, in restrained or unrestrained
conditions. Conditions of acceptance for the ASTM E 119-00
and E 119-61 tests were described. These conditions differ
for restrained and unrestrained test assemblies. Photographs
were provided showing the preparation of the test assemblies,
the furnaces in Toronto, Canada, and Northbrook, Illinois,
and post-test observations.
Results and observations were then reviewed. In summarizing
the tests, Dr. Gross stated that the test structures were able
to withstand fire conditions for between 45 minutes and 2 hours.
The restrained floor system with 0.75 inch fireproofing as
installed obtained a fire resistance rating of 1.5 hours, while
the unrestrained floor system achieved a 2 hour rating. Past
experience with the ASTM E 119 test method would lead investigators
to expect that the unrestrained floor assembly would not perform
as well as the restrained assembly, and therefore, it would
receive a lower fire rating. The 45 minute fire resistance
for the standard 17 foot floor system with a specified 0.5
inch fireproofing would not have satisfied the 2 hour requirement
of the 1968 New York City Building Code. The 2 hour fire resistance
for the standard 17 foot floor system with the as applied 0.75
inch fireproofing met the 2 hour requirement of the New York
City Building Code. The likely cause of the difference in results
is not the fireproofing thickness on the trusses themselves,
but the presence or lack of fireproofing on the undersides
of the metal deck. The results raise the question of whether
or not fire rating based on the ASTM E 119 performance of a
17 foot span floor assembly is scalable to a larger floor system,
such as found in the WTC towers where spans ranged from 35
feet to 60 feet.
Issues include adequacy of the ASTM E 119 standard to provide
guidance on (1) criteria for determining structural limit states,
including failure, and means to measure them; (2) scale of
test assembly versus prototype application; (3) effect of end
restraint conditions on test results; (4) structural connections;
(5) combination of loading and exposure adequately represent
expected conditions; (6) procedures to analyze and evaluate
data from fire resistance tests and other building components
and assemblies to qualify an untested building element; (7)
repeatability and reproducibility of test results; and (8)
relationships between prescriptive ratings and actual performance
of the contraction in realistic building fires.
Q: There was spalling on the underside of the assemblies in
the large-scale restrained test. Was there similar spalling
on the unrestrained and the smaller scale test assemblies?
A: Yes, the unrestrained test showed similar spalling, but
to a lesser degree as evidenced by the amount of bowing. Spalling
was a little bit delayed in these tests. It was more severe
for the restrained test condition. Explosive spalling occurred
on the top of the slab in both of the Northbrook tests.
Q: Did you do destructive analysis? One observation we tried
to make was that compression occurs at the knuckle. Will you
be able to dissect that area to determine localized crushing
for continuity?
A: There was cracking at the first knuckle; that’s what
Dave Collins is referring to. We’ll do our best to check
that.
C: There is a limit
on the number of tests, so I suggest doing mathematical modeling.
Also, I suggest modeling the difference
between tests and the actual connections used in the building.
Also, consider modeling ¼ inch and 0 inch thicknesses
of fireproofing on the diagonals of the floor trusses.
A: The connections were intentionally strong for the restrained
test. The unrestrained specimen was faithful to the actual
connections in that bolts were provided and the truss could
expand. We can go back and do some modeling. I don’t
know if elongation (tension) occurred in the diagonals.
Back to agenda
Project
6 – Strength
and Impact Response of SFRM
Dr. John L. Gross, WTC Investigation, Project 6 Co-Leader
PRESENTATION (pdf file)
Dr. Gross summarized information regarding the strength and
impact response of spray-applied fire resistant materials (SFRM).
The NIST study attempted to determine the force required to
dislodge SFRM from structural steel members, using in-place
density and bond strength, laboratory static strength properties,
and impact tests.
Tests were performed on 8 inch by 16 inch by 0.25 inch plates
and 1 inch by 20 inch bars with and without primer. Adhesive
strength and cohesive strength were measured.
Results indicate poor adhesion to primed surfaces with good
adhesion to bare steel. For unprimed specimens, cohesive strength
is similar to adhesive strength. Adhesion to planar elements
is controlled by adhesive or cohesive strength, whichever is
smaller; for a bar it is controlled by cohesive strength parallel
to the surface. Dynamic tests are ongoing.
Q: Regarding the
impact tests, you haven’t finished
the acceleration results?
A: That’s correct.
Q: How many passes are needed to get the 1.5 inch thickness
of spray-on fireproofing?
A: Two to three passes are needed. The supplier came back the
second day and touched up the fireproofing.
Q: How long would you have to wait between passes to apply
in the field?
A: We waited a day between passes. The binder is Portland cement.
Q: Was there cohesive strength data for primed steel?
A: No. The cohesive property is a test of the fireproofing
only. The presence of primer affects only the adhesive properties
test.
Q: Has anyone researched the primer used in the WTC towers?
A: We used the same primer as used on the exterior panels.
We could not get the same primer as used for the trusses.
C: In general, most engineers prefer painted steel, not rusted,
and without primer. The fireproofing sticks better. Some are
comfortable with steel being primed; the feeling, though, is
without primer is better.
Q: Did you measure thermal conductivity and diffusivity?
A: The thermal conductivity and diffusivity were measured in
Project 5.
Back to agenda
Project
6 – Structural
Fire Response and Collapse Analysis
Dr. Therese P. McAllister, WTC Investigation, Project 6 Co-Leader
PRESENTATION (pdf file)
Dr. McAllister summarized information regarding the structural
fire response and collapse analysis. The objective of the Project
6 study is to determine the structural response of the WTC
towers to aircraft impact and internal fires and to identify
the most probable structural collapse mechanisms.
NIST developed and used a comprehensive approach to determine
the probable collapse sequences from aircraft impact to collapse
initiation. This approach combined mathematical modeling, well-established
statistical and probability based analysis methods, laboratory
experiments, and analysis of photographic and videographic
evidence. The approach allowed for evaluation and comparison
of possible collapse sequences based on different states, fire
paths, and structural load redistribution paths. The approach
accounted for variations in models, input parameters, analyses,
and observed results. A flow chart was then projected that
showed the sequence and interdependencies of the analyses that
were performed.
Dr. McAllister stated that extensive sensitivity analyses
using Orthogonal Factorial Design (OFD) were conducted to determine
the most influential factors for each analysis step used in
determining the probable collapse sequence. This included developing
factors for the realistic case, more severe case, and less
severe case.
Dr. McAllister then described the leading hypotheses for collapse
of WTC 1 and WTC 2, which identify the specific damage scenarios
and load redistribution paths for each tower. Both hypotheses
involve (1) damage to the building support columns, floor framing,
and fireproofing due to the aircraft impacts; (2) subsequent
fires that softened the steel core and perimeter support columns;
(3) buckling of support columns; and (4) global collapse. The
leading collapse hypotheses will continue to be refined until
the analyses are complete.
Dr. McAllister reviewed the damage to the WTC towers produced
by the aircraft impact and how stresses were redistributed
by the floor system and to a lesser extent the hat truss to
the remaining undamaged columns.
Structural response to fires subsequent to impact damage included
core column shortening, perimeter column bowing and buckling,
and floor sagging and pulling. This is consistent with photographic
evidence showing the inward bowing of the perimeter columns
on the south face of WTC 1 and east face of WTC 2 approximately
5 to 10 minutes prior to collapse.
Truss temperature exceeded 500 to 600 degrees Celsius only
where fireproofing damage and fire exposure occurred. Damage
to the fireproofing was extensive near the impact areas.
Dr. McAllister noted that the final analyses are currently
under way. These analyses are attempting to come to closure
on issues involving large plastic and creep deformations and
kinking (non-linear buckling) induced by localized plastic
deformation. A global analysis is also being performed to determine
the structural response of the WTC towers to large fires without
impact damage.
Issues identified by Dr McAllister include (1) availability
of explicit standards, code provisions, methodology, analytical
design tools, and practical design guidance for designing structures
to resist progressive collapse in the event of abnormal loads;
(2) availability of analytical methodologies for prediction
of complex failure phenomena of structural systems under abnormal
loads; (3) availability of standards, codes, methodology, analytical
design tools, and practical design guidance to permit considering
fire as a design condition for the structure as a whole system;
(4) availability of regulations that would adopt code provisions
using the structural frame approach to fire resistance ratings,
which requires structural members to be fire protected to the
same rating as columns; (5) applied passive fire protection
conformance to conditions in actual or equivalent tests used
to establish fire resistance rating of the building component
or assembly; and (6) availability of regulatory requirements
for retention of documents related to the design, construction,
operation, maintenance, and modifications of buildings, including
retention offsite.
Q: In the absence of impact, fire only, burnout would have
been achieved and the building would not have collapsed? Am
I interpreting that correctly?
A: Yes. For the fires we have analyzed to date for floor systems
with ¾ inch fireproofing in place, even with gaps observed
in photographs, the floors would have deformed, but would not
have initiated collapse.
A: We have looked at credible fires in an undamaged tower.
Remember, for this scenario, there would not be broken windows
to supply oxygen to fuel the fire. This is a working hypothesis
and analyses remain to be completed.
Q: Regarding the
findings for global analysis with impact damage, I want to
make sure I’m interpreting the information
correctly for floor 96 in WTC 1. At 600 seconds, there’s
23 inches of deflection on the trusses. When the fires move
away, the trusses restore to 6 inches of deflection?
A: Yes. The 23 inches is next to the impact area.
C
(NIST): Referring to the slide on global analysis without
impact damage. You have a statement that burnout was likely
prior to collapse. This infers that collapse would occur. You
may want to change your wording to say burnout without collapse.
A: Agree.
Q: Do you have a complete run for the entire buildup of the
tower?
A: We have completed the realistic case for WTC 1. The realistic
case for WTC 2 is running and may be completed later today.
We’ve also done the component analyses.
Q: Can you envision another set of conditions that gives the
same observed failure mechanism?
A: We had to remove four to five floors to get global instability.
A: We looked at this very carefully. We could not find a way
to make the building come down.
Q: As the fires moved, the trusses cooled but the slab continued
to heat? Why?
A: The slab is 4 inches thick. The center is cooler than the
surface. The center of the slab continued to rise in temperature
to reach equilibrium with the warmer upper and/or lower surfaces
of the slab.
A: The concrete slab has a very high temperature on the surface
and a steep temperature gradient resulting in low temperatures
in the center of the concrete slab. As the fires move away,
the high temperature on the surface equilibrates, which results
in lowering of the surface temperature, but the temperature
of the inner layers of the concrete slab can increase.
Q: In the column areas in the debris field, you assume that
fireproofing was knocked off. Did you make the same assumption
for the open web joists that were in the debris field?
A: Yes.
Q: How did you model
connections of the floor beam and the core to the columns?
Did you model them per the shop drawings—the
axial capacity? I’m surprised that you get a lot of redistribution
of vertical load from the inside to the outside. My understanding
is that all the column connections of the beams and the core
are basically shear tab connections with no moment capacity
and that a 60 foot long joist isn’t going to be transporting
much vertical load unless you’re talking about a global
three-dimensional model.
A: What you’re saying is true for a truss, but when you
look at the entire floor system and think about a plate with
a hole in the middle and start pushing down on a plate, you
get a different response than you would expect for a single
truss.
A: The connections were largely pinned, and they were modeled
as pinned; those that were fixed were modeled as fixed. The
5 inch slab floor system participated with the beams.
C: The term “shortening” implies compression shortening.
Maybe you should use “bowing” instead.
Public Comment Period
Dr. Hanson, the acting Committee chair, stated the ground
rules for presenting public comments. Each speaker had 5 minutes
to address the Committee. Members of the public may submit
their comments in writing at the meeting or at any time.
Dr. Hanson called the first speaker to the podium, Mr. Jake
Pauls.
Jake Pauls, Jake Pauls Consulting Services
STATEMENT (pdf file)
Mr. Pauls addressed occupant behavior and egress issues. He
presented a synopsis of his 16 pages of comments on NIST Special
Publication 1000-5, Progress Report on the Federal Building
and Fire Safety Investigation of the World Trade Center Disaster,
June 2004 (June 2004 Progress Report), which were submitted
by the Skyscraper Safety Campaign. He stated that one of the
problems with the Progress Report was the difficulty in finding
specific topics because there were no bookmarks provided with
the PDF files on the Web.
He questioned the data on the initial population estimates.
Mr. Pauls and others would like to better understand how the
estimates were obtained. He discussed the predictions of evacuation
times and said there was not enough detail on the models, such
as the input assumptions and the outputs.
Mr. Pauls indicated that he has a major issue with the discussion
of exit stairway remoteness in the June 2004 Progress Report.
He stated that there is immense detail dealing with other issues,
such as perimeter column damage, but not for figures that represent
the floor area showing the stairs. In his professional opinion,
the exit stairs were grossly out of code.
Mr. Pauls said that the information on the size of the floor
areas, which is essential for determining occupant load, was
missing, and that basic information about the egress system
in the building was not provided.
Mr. Pauls did not
agree with NIST’s statement that it
has received all of the essential information because NIST
staff had stated earlier at that day’s meeting that they
did not have the detailed floor plans for WTC 2.
Mr. Pauls commented on the analysis of first-person accounts,
some of which were accounts of human dramas taking place on
the morning of September 11, 2001. He stated the need to carefully
question the use of such accounts. He also questioned the reliability
of the chain of recording and the characterization of evacuee
behavior as pushing, shoving, and yelling.
Dr. Hanson called the next speaker, Dr. James Quintiere.
James Quintiere, University of Maryland, Department of Fire
Protection Engineering
STATEMENT (pdf
file)
STATEMENT (pdf file) Professor Quintiere said that one of the critical things he
had heard at the meeting is that removing insulation from the
core columns is a very critical event in explaining what happened
to the towers. He added that there had not yet been significant
explanation to convince him this is what happened.
He then presented
his comments on NIST Special Publication 1000-5, Progress
Report on the Federal Building and Fire Safety
Investigation of the World Trade Center Disaster, June 2004
(June 2004 Progress Report), which were submitted to NIST by
the Skyscraper Safety Campaign. Although much information and
analyses have been compiled, he indicated that the NIST information
is far from complete as many results and details are not included
in the June 2004 Progress Report. He commended the building
and fire groups of NIST for conducting a significant, collective
study for the first time. He stated, however, that the investigative
conclusions need to have focus, clarity, and impact. Professor
Quintiere’s questions and comments focused on the following
areas: the temperature reached by the fire and by the steel,
the accuracy and consistency of the computer modeling predictions
for the fire environment, and the NIST working hypothesis for
collapse, including impact computations, single truss analysis,
E119 standard fire tests, and insulation history.
Dr. Hanson called the next speaker, Ms. Sally Regenhard.
Sally Regenhard, Skyscraper Safety Campaign
STATEMENT (pdf file)
Analysis
from Professional Advisory Panel (pdf file)
Joint
Subcommittee Overview of WTC Investigation (pdf file)
Subcommittee
on Buildings & Fire Codes (pdf file)
Ms. Regenhard expressed that after September 11, 2001, she
and 343 firefighter families and the families of the victims
were outraged that something like the collapse of the WTC could
happen. She led a delegation of parents and families to Congress
to demand valid investigation. With the help of the House Science
Committee and Congressman Sherwood Boelhert, they picked NIST
to do this investigation.
She thanked NIST
and all the people that she has worked with continuously
for almost 2 years now. Ms. Regenhard said that
she was very happy to advocate for this investigation and thanked
the members of the federal advisory committee. Her organization,
the Skyscraper Safety Campaign, is a voluntary organization,
and she indicated that some of her professional advisors were
at today’s meeting and had just testified. Ms. Regenhard
said that she knows what it is to have people of the Committee’s
caliber give their time essentially for free. But they are
doing it because they are doing good and she knows that their
work is going to save people’s lives in the future. She
stated that it’s too late for the over 2,700 innocent
victims, most of them who died needlessly in a death which
certainly could have been avoided if people did their job and
if buildings were constructed in the safe manner and with means
of egress to get out of a dangerous building.
Ms. Regenhard submitted
reports by the Skyscraper Safety Campaign’s
professional advisors and subcommittees. The major issue the
Skyscraper Safety is concerned about is the character and the
intention of the WTC Investigation June 2004 Progress Report—research
and fact finding versus forensic investigation. Although the
report contains a great deal of genuine research and fact finding,
the Skyscraper Safety Campaign feels that the collection of
data cannot take precedent over the investigative intention
of the congressional mandate. She stated that the public demands
to know why, as well as how, the WTC collapsed, and there is
a need to correct errors in order to avoid such catastrophes
in the future.
She said that NIST should aggressively assert itself as the
appropriate center for forensic engineering and investigation
of construction, fire, or egress disaster, using the full power
granted by the congressional legislation and modeling its role
on that of the National Transportation Safety Board.
Ms. Regenhard expressed
her disappointment that she was not hearing anything in that
day’s meeting on building code
requirements, violations, and interpretations. The issues regarding
local building codes and the Port Authority’s ability
to abrogate them, reinterpret them, and substitute its own
proposal with or without full testing or outside evaluation
needs to be fully addressed. She stated that critically important
aspects of the construction and the subsequent loss of life
are connected to design decisions made by the Port Authority,
including structural issues concerning the use of light weight
truss systems for floor support as part of the primary structure
system.
Ms. Regenhard said
that the other issues involved documentation, modeling, and
testing. There are serious doubts about the sufficiency
of existing fire testing, virtual or real, especially the use
of scaled elements. Moreover, there seems to be an insufficient
concern for human behavior scenarios that give needed insight
into egress system’s operational effectiveness.
Dr. Hanson called the next speaker, Mr. Robert Polk.
Robert Polk, National Association of State Fire Marshals
STATEMENT (pdf file)
Dr.
Hanson called the next speaker, Mr. Richard Kuchnicki.
Richard Kuchnicki, International Code Council
STATEMENT (pdf file)
Dr. Hanson
thanked the speakers and concluded the public comment session. Back to agenda
Project
8 – Emergency
Response
Mr. J. Randall Lawson, WTC Investigation, Project 8 Leader
PRESENTATION (pdf
file)
Mr. Lawson presented an update on emergency response. He summarized
changes after the 1993 bombing, including the establishment
of the Office of Emergency Management (OEM), the agreement
of Port Authority with the New York City Fire Department (FDNY)
regarding fire safety, the installation of an FDNY high-rise
radio repeater in the towers, and the upgrading of the WTC
elevator intercom system.
To gain information
for the investigation, NIST conducted face-to-face interviews
with 68 FDNY personnel, 25 New York
City Police Department (NYPD) personnel, 15 Port Authority
staff, and 3 others from security, fire safety, and communications.
Mr. Lawson explained the role of each responding department
on September 11 and FDNY’s initial size-up of the WTC
conditions.
He pointed out that emergency responders were implementing
three different operational strategies and that no first responders
interviewed by NIST thought that the WTC towers would totally
collapse. The outside command posts and inside command communicating
with the outside had the strategy to evacuate and rescue all
below the fires. The objective for the command officers for
inside operations was to get enough personnel and equipment
upstairs to cut a path through the fire to rescue occupants
above the fire and evacuate and rescue all below the fires.
The strategy for the company level command was to get up to
the fire floors and extinguish the fires. He stated that situational
awareness varied from adequate for those outside the buildings
that could see what was going on, to poor for those inside
the buildings that could not see what was happening and that
had poor radio communications.
Mr. Lawson reviewed the location FDNY, NYPD, and Port Authority
Police Department (PAPD) command posts, as well as the details
of staging, assignments, and personnel accountability on that
day. Although some freelancing (not officially assigned) was
experienced, emergency responders generally followed their
department protocol. Many FDNY units assigned to the WTC site
did not know WTC 1 from WTC 2. Mr. Lawson reported that personnel
accountability lists were typically maintained on magnetic
boards or paper, and with the collapse of WTC 2, all accountability
lists for each department were lost. No records were maintained
beyond the WTC site.
Mr. Lawson described the access to the buildings after aircraft
impact. Only two elevators out of 198 were operating inside
the two towers. The stairways were filled with occupants trying
to evacuate. FDNY personnel and other emergency responders
had to deal with the challenges of counterflow, the weight
of personal protective equipment and gear, and climbing more
than 10 to 12 flights of stairs. The estimated climbing rate,
based on a 60 minute climbing period to the maximum height
achieved, is 1.4 to 2 minutes per floor.
Standard evacuation procedure was down the stairs to exit
at the bottom of the WTC towers, not roof evacuation. Mr. Lawson
discussed the NYPD and FDNY roof rescue protocols, which were
basically the same. The FDNY air support plan objectives include
providing FDNY with the capability of placing fire personnel
on the roof for the purpose of ventilating and search, comforting
people who are trapped, evacuating persons in need of immediate
medical attention, and evacuation as a last resort. The Port
Authority reports that it never advised tenants to evacuate
upward.
Mr. Lawson provided details on the emergency responder radio
systems, the FDNY radio communications systems, and the readability
analysis of radio communications. All three responding departments
(FDNY, NYPD, and PAPD) experienced difficulties with radio
communications. Two basic issues were normal function of the
radio equipment in high-rise environments and the volume of
radio traffic. Roughly one-third to one-half of the radio messages
transmitted during the radio traffic surge conditions was not
complete or understandable.
Mr. Lawson explained that first responders did not have adequate
information on, nor an overall perspective of, the conditions
in the WTC towers and what was happening elsewhere at the WTC
site, and that interagency information sharing was inadequate.
A significant amount of evidence (first-person interviews,
reports, and photographic data) shows that the different agencies
were working together during the WTC disaster). Interagency
operations were detrimentally affected with the loss of the
OEM command center that was located inside WTC 7. NIST interviews
with first responders suggest that interagency competition
had minimal effect on operations at the WTC complex on the
morning of September 11, 2001. The data also suggest that some
of the problems experienced were due to personnel not understanding
the operating practices of the other agencies.
Command and control difficulties began with the dispatch of
large numbers of firefighters to the WTC before adequate command
posts and staff could be assembled to manage them. Mr. Lawson
said that FDNY command and control was seriously affected by
the lack of good communication and that their system of maintaining
assignment records could not manage the number of units and
personnel. In addition, he emphasized that there was no means
to back up the unit assignment records for FDNY, NYPD, or PAPD.
Mr. Lawson identified issues that need to be addressed in
changes to practices, standards, and codes and identified alternative
practices and technologies that may address these issues. In
the areas of access and firefighting, the issues are (1) physiological
impact on firefighters with equipment climbing more than 10
to 12 floors during an emergency, (2) adequacy of capacity
for egress and firefighter access during full evacuation of
fully occupied tall buildings, and (3) distance between stairwells
where standpipes are located. For emergency communications,
the issues are (1) lack of rigorous preemergency inspection
and testing of radio communications systems within high-rise
buildings to identify performance gaps and inadequacies, (2)
performance requirements for emergency communication systems
in buildings, and (3) lack of communications network architecture
(interoperability) and operational protocols for intra- and
interagency communication at all levels of organizational hierarchy.
Command and control issues include (1) availability of detailed
procedures for gathering, processing, and delivering situational
information to all first responders; (2) availability of effective
codes and protocols for establishment and uninterrupted operation
of the incident command and control system and for preservation
and dissemination of information; (3) rapid adoption and execution
of a unified emergency response mission by all first responder
ranks; and (4) the dispatch of large numbers of personnel and
apparatus and the ability of management to maintain accountability
in a timely manner associated with arrival and deployment of
personnel, and the ability of the incident site to effectively
accommodate large numbers of personnel and apparatus.
Q: Having three
operational strategies for emergency response is like having
none. How do you end up with three strategies?
We need to be sure we have a good basis for this finding. Was
the upper level strategy not being communicated? Why couldn’t
this be communicated to the next level in the command chain?
A: There are clearly three concepts here. The level of the
individual is considered as well as the years of experience
and their perception. High-ranking officers were having trouble
with communications. Also, once inside the building, they realized
the fires were too big to fight. There was a blending over
time. Situational awareness changed with location. There was
a short window of time for response.
C: There is a common theme of information transfer or lack
thereof.
Q: The accountability lists were lost. Is there any indication
about the accuracy of locations of units and buildings?
A: The indication is that the lists were not complete.
Q: There is a report of firefighters on the 78th floor. What
does that do to the climbing rate?
A: They took the elevators to the 40th floor and walked up
the rest of the way.
C: The firefighters on the 78th floor had no gear. One was
a marathon runner.
A member of the public, without invitation to comment, offered
a personal statement about these items and this project.
Dr. Hanson thanked the presenters, attendees, and speakers.
He adjourned the meeting at 6:15 p.m.
October 20, 2004
Dr. Hanson called the meeting to order at 8 a.m.
Back to agenda
Project
7 – Occupant
Behavior, Egress, and Emergency Communications
Mr. Jason D. Averill, WTC Investigation, Project 7 Leader
PRESENTATION (pdf file)
Mr. Averill noted that first-person accounts were gathered
from 225 interviews of occupants of WTC 1, 2, and 7; over 800
telephone interviews of occupants of WTC 1 and 2; and 6 focus
groups. He presented an estimate of the number of decedents
above and below the impact regions in WTC 1 and WTC 2, along
with predominant factors associated with occupants who did
not successfully evacuate. The initial population in WTC 1
and 2 at 8:46 a.m. on September 11, 2001, is estimated to have
been approximately 17,400, plus or minus 1,200 persons. The
majority of the deaths in the region below impact were accounted
for by being trapped by debris on the starting floor, delayed
evacuation initiation, or performing emergency response building
responsibilities.
Next, observations of building damage in WTC 1 and WTC 2 from
a variety of eyewitness accounts were presented. Mr. Averill
stated that Stairwell A in WTC 2 was passable for a period
of time after the aircraft impact.
Mr. Averill reviewed the public address system announcements
made in the towers on September 11, 2001, and noted that opportunities
to improve occupant situational awareness were often lost.
Specific knowledge about locations of fires and impact damage
was only occasionally communicated to occupants who requested
the information and was without apparent coordination. For
example, some operators advised sheltering in place while others
advised evacuation.
The causal model results for evacuation initiation delay and
normalized stairwell evacuation time were presented, along
with more general findings regarding the overall evacuation
process. Mr. Averill then noted that despite perception of
some occupants, counterflow was found to not be a significant
factor in the total evacuation time when compared to other
factors.
He noted that after aircraft impact, most of the emergency
communication system in WTC 1 was disabled. All three stairwells
in WTC 1, and two of the three in WTC 2, were rendered impassable
in the area of impact. The PANYNJ reports that it never advised
tenants to evacuate upward.
Occupants were often unprepared for the physical challenge
of full building evacuation. Mobility-challenged occupants
were not universally identified nor prepared for evacuation.
Occupants were often unprepared to encounter transfer hallways
during the stairwell descent. Phased evacuation (defend-in-place)
would not have been an appropriate strategy. He noted that
approximately 87 percent of the WTC tower occupants were able
to evacuate successfully, including more than 99 percent below
the floors of impact. Use of elevators in WTC 2 saved roughly
3,000 lives.
Finally, Mr. Averill
introduced the issues related to the design and performance
of the egress system, emergency communications,
occupant preparedness, and evacuation technologies. Some of
these issues include (1) that building egress systems are not
designed to accommodate full building evacuation; (2) stairwells
can be physically proximate yet considered remote by a “walking
path” measurement; (3) procedures for identifying and
assisting mobility-challenged occupants may be insufficient;
(4) the emergency broadcast system may be useful in large-scale
emergencies; (5) emergency plans are filed to achieve regulatory
compliance, but may not be adequately implemented in practice;
(6) elevator door restrictor plate can entrap occupants in
the event of an emergency; and (7) lack of adequate egress
models and systematic methodology for accounting for human
behavior during evacuation.
Q: Were observations of damage made at any time during egress?
A: Observations were made directly after impact. In WTC 1,
people were still on the same floor. In WTC 2, many people
had already begun their evacuation before the impact of the
aircraft.
Q: Regarding the occupants who may have been from the impact
zone in WTC 2, is it possible the descending persons were firefighters?
The Palmer tape mentions firefighters in the twenties in WTC
2.
A: The interviewee did not identify them as uniformed personnel.
A: It is not stated explicitly, but it appears clear they were
not firefighters. The interview indicated that firefighters
were on the way up.
A: We don’t know where these persons were coming from.
That’s why we are tempered in the way we state the finding.
Q: What is the issue of architects not being trained in egress
system design based on?
A: Discussion of the issue of what it is that constitutes egress
system design and what is it that qualifies someone to do design
egress systems.
Q: With respect to the evacuation speed reported, how were
speed and rate determined?
A: The speeds were determined from reported time that occupants
spent in stairwells from the generalized interviews.
Q: It was self-reported?
A: Yes.
Q: And the rates?
A: For the stairwell door exit rates, we took the total population,
averaging it over the 100 minutes and dividing it by the
three stairwells, and knowing what the effective width is,
which is different than the clear width. This gives you a
number of about 37 people per minute going out each door
on average over those 100 minutes.
Q: Are the speeds for total time in the stairwell or do they
include rests that might be taken out of the stairwell?
A: They are based on the total time spent in the stairwell.
Q: Any idea why evacuation rates were so low?
A: People reported they were moving as quickly as they could.
The flow in general was the limiting factor. In addition,
they reported the environmental conditions in the stairwells
of smoke, water, etc, and the physical challenge of going
down 1,000 feet worth of stairs for some people was difficult.
Q: Did the towers meet the remoteness requirement in the New
York City Building Code?
A: When the towers were originally designed, remoteness was
defined as being as remote as practicable. It would not have
met the half and third diagonal rule used in the current code.
Q: Communication issues are more of a general problem than
some of the other issues. Was the counterflow issue one of
perception? The emergency services going up are hitting a constant
stream, whereas the people going down are only hitting counterflow
every so often.
A: There is an issue of perception. People did encounter firefighters
and stepped aside to let them pass. Statistics showed that
the counterflow was less of an issue than other factors, which
overwhelmed the counterflow issue.
C: It’s probably worth stating that the general result
about counterflow being less of a problem compared to others
has to be taken in context. It does not mean that specific
individuals were not affected significantly by counterflow
or that firefighters always were affected by counterflow. Those
are all consistent statements.
Q: Could it also be that persons were affected by counterflow
and didn’t even realize it?
A: We measured how it affected their total evacuation time.
If it had a significant detrimental effect, their evacuation
time would be longer than for those who didn’t encounter
counterflow of significant degree. Finishing the hypothesis,
there was a rate limiter at which the people were moving as
quickly as they were allowed to move given the conditions inside
the stairwell, but they weren’t moving as fast as they
might otherwise in a clear stairwell. Therefore, if they have
to step aside to allow a firefighter to go by, they can make
up that time by moving faster and they are no worse off than
they were before. From the flip side, if you look at a firefighter,
the limiting factor appears to be the physical condition and
how much they were carrying, and they were moving up essentially
as quickly as they could. If you delay that person by any period
of time, they can’t make it up by moving faster. So,
those two conclusions—that counterflow had an effect
on the firefighters, but not a significant effect on the occupants—are
consistent if we understand the rate limiting factor.
C: I’d like to pick up on Dave Collin’s question
and address two issues. One is the question of egress training
for architects and the other is the design of a core. In smaller
buildings, for example two-story buildings, usually architects
are responsible for most of the design and interpretation of
the code. In tall buildings, there is usually a code consultant,
a fire consultant, and other types of consultants. I’m
sure to pass the RA exam you need to understand the code and
egress, at least to a degree, as an architect. We don’t
need a new profession. Today no one looks at structural design;
everyone looks at egress. The design of the core in a high-rise
building is like war. The owner wants the core reduced to maximize
rental space, the architect has his own design, the structural
engineer wants space for the columns, the fire protection engineer
wants stairs in the right location, the mechanical engineer
wants mechanical and electrical systems in the best space.
Where the shafts for mechanical, electrical, and plumbing systems
are located is probably not an important consideration. The
location of fire stairs is probably more important than anything
else. In Kuala Lumpur, we added a stair in the bustle. No one
wanted it, but we added it anyway because the path and distances
were there. We looked at several international codes and synthesized
what the best had to offer. A formalized hierarchy of importance
for certain size projects needs to come out in this study.
A: We will look at the issue. It’s very important. We
will also look at the architect training issue and modify it.
Q: Architects are
currently required to be certified in life safety. I’m not sure this criticism is warranted. Also,
in the comment about the stairwells being physically proximate,
was the term “practicable” in the remoteness issue
a contemporary criterion at the time these buildings were being
built?
A: The issue of measurable diagonal came up after the 1968
building code.
Q: So the use of practicable remoteness was a standard of practice
when these buildings were built?
A: That’s my understanding.
Q: Obviously a difficult term to interpret by anyone’s
measure.
A: I’ll take a closer look and verify that.
A: The code language was changed from “as remote as possible” to “as
remote as practicable.” The code people at the time said
it was meaningless.
C: That is my understanding as well. You need to tie it back
to what the practice was at the time. You use the “walking
path” or what is typically dealt with as a means of some
sort of separation that you have to walk around, typically
a fire barrier, to measure the distance between stairwells
and you say that that is not adequate under nonfire conditions,
such as overpressure. What does that mean?
A: If stairwells are physically close, the 2 hour fire separation
may not be adequate for both stairwells to survive, if overpressure
is a design consideration.
Q: With regard to
stairwell capacity, are we comparing apples and oranges?
Doesn’t that include people not going through
the door?
A: The data are for a total uncontrolled building evacuation.
The average value is under a fire drill scenario.
C: If you have more people in the stairwell, the number would
go up.
C
(NIST): One thing special about this event is that the handicapped
persons in the stairwell become much more of an obstacle than
any fire department counterflow. We need to consider this.
We must pay more attention to this issue, which will be an
issue in every evacuation.
C: It is the whole issue of faster versus slower people and
having to go around people who are handicapped.
C (NIST): As Jason’s material reports, a good deal of
the handicapped people self-evacuated by holding both handrails
and taking one step at a time, cutting their rate way down,
forcing them to occasionally step aside to let others pass.
It is still a major problem for research and development.
Q: Regarding the issue with rooftop evacuation, I wonder whether
the opposite of the statement is true. Did the Port Authority
tell people not to go up, especially since people were rescued
from the rooftop in 1993? This is an important distinction.
A: No, we don’t have any evidence that the Port Authority
told people not to go up. One Port Authority employee was instructed
to go down. He went as far as he could. Then he was instructed
by a Port Authority individual to go to the roof. We don’t
have good information on this.
C: I would like to get your perspective on how we view this.
Over half of the occupants were in the buildings for 3 years
or 4 years or less. Should evacuation instructions include
things that should not be done? In this particular case, it
was roof evacuation. The roof access was locked, and the roof
was not available. For other buildings, it might be something
else. Should training include things you don’t have to
do or should not do? That is an important question.
C: Yes.
Back to agenda
Project
4 – Investigation
of Active Fire Protection Systems
Dr. William L. Grosshandler, Chief, Fire Research Division
PRESENTATION (pdf file)
Dr. Grosshandler presented the issues and supporting findings
for the active fire protection systems investigation. Dr. Evans,
the Project 4 leader, retired from NIST. The first issue Dr.
Grosshandler discussed was the minimum level of performance
for active fire protection systems. The fire sprinkler systems
design method for WTC 1, 2, and 7 was based on the occupancy
hazard fire control approach from NFPA 13, Standard for
the Installation of Sprinkler Systems. NIST found that the installed
fire sprinkler systems in the WTC buildings exceeded minimum
NFPA requirements. He also discussed automatic versus manual
operation for fire sprinkler, fire alarm, and smoke purge systems.
Dr. Grosshandler noted that some systems were vulnerable to
single point failures: WTC 1, 2, and 7 fire sprinkler and standpipe
systems; WTC 1 and WTC 2 fire alarm system voice notification
and fire warden and firefighter telephones. If these systems
are breached, the systems fail, as they did on September 11,
2001.
The second issue Dr. Grosshandler discussed was the adequacy
of information provided by fire alarm and communications systems
for the management of emergency response and evacuation. The
third issue was the transmission of fire alarm and building
systems information outside the building to enhance situational
awareness of first responders and to aid in response decisions
during emergencies.
The final issue
that Dr. Grosshandler presented was with the survival of
fire alarm system and other building status records
of events for investigation purposes, either through offsite
transmission or an onsite “black box.” He explained
that alarm systems collect information that is valuable for
understanding the fire and smoke development. Although modern
systems are capable of transmitting data outside a building
to monitoring stations, it is not done in practice. No information
from the fire alarm system was recovered.
Q: Was the manual pull station information sent directly offsite
to the fire department?
A: We will check that.
C: In the data from WTC 7, the transmissions correspond with
the collapse of WTC 2. Offsite monitoring is a good idea. The
problem is with the data being transmitted. But black boxes
are a good idea; offsite transmission does not give the same
level of detail.
A: Offsite data transmission can be used to assist with the
response and recovery.
C: For the future, transmitting data to responding firefighters
will be very useful.
Q: In a modern high-rise
office building, you won’t
get a lot of good information from the alarm system to improve
the evacuation process. There is no generalized requirement
for information. If the system was not severed, you would have
gotten a slew of information. The system doesn’t provide
information to intelligently direct evacuation. It won’t
materially improve response and evacuation.
Q (NIST): Are there pieces of information that would be useful?
C: Extended range analog smoke detectors, thermocouples, etc.
That’s a big code question—what information should
you have.
A: That would be a logical thing to address in this report
because we want to address big code issues.
C: Yes, that’s what I’m arguing for. In other words,
back off—we’re make a big deal about the survivability
of the network and the transmission of the data, and the point
is there is no data to transmit.
C
(NIST): In relationship to the black box approach, in WTC
2, the system could take in data from other security inputs.
The control room was constructed like a bank vault, but it
was not found following the collapse.
Q: The issue of
fiber optic versus copper should not matter. I think in this
particular architecture, it depends on how
the connections are made. It’s something to check.
A: The Style 7 system addresses that issue. All the major manufacturers
have systems that can be installed and wired as a Style 7 system.
It could have been done and doesn’t necessarily need
to use fiber optic; there are other ways of doing it.
Q: On the issue 1 finding, it is stated that the sprinkler
system met or exceeded the requirement? What does this mean?
A: National Fire Protection Association (NFPA) 13 gives the
minimum requirement. The statement is based on calculations
performed by our contractor which showed that the flow rate
was greatly exceeded, and, therefore, was a robust system for
ordinary office fires.
Q: I want to reiterate
what Phil was saying. What do you do with all the data? Just
transmitting data to a truck en route
is not adequate if we don’t have people who are ready
and knowledgeable and have enough information to really do
the job that needs to be done when they get there.
A: Yes, you are absolutely right. We have a parallel research
effort that started well before September 11, 2001, to exactly
work these aspects.
A: Hopefully, this will be similar to the police, for example,
where they have systems in their patrol cars that can pull
up people’s records and check them out.
Q: Commercial high rises are built without a tenant and are
not built to suit. Owner-occupied buildings have better systems.
Are such systems available?
A (Committee Member): You can’t tell the commercial developer
that he needs to install these systems, but they are available
if desired. And the building would be drastically improved.
C: Systems are available. NIST should inform the public that
these systems are available even though you can’t tell
a commercial developer they have to put these systems in their
buildings.
C (NIST): Which has been done in some cases, for example, pick
up data from your ordinary thermostats.
C: There are systems technology that we use for building management,
such as energy, lighting, etc, that parallel what we’re
talking about here. And even in a commercial building, it isn’t
that extraordinary to imagine that those systems can do it.
The real issue is not designing those elements to provide us
the data; it’s what to do with it.
C: If it was a hotel, you’d have more information.
C: Just because it’s a lot of data, does not mean we
shouldn’t do it. Getting 50 smoke detector bits of information
can be overwhelming, but there is a lot of useful information
that can be transmitted. Getting better data to people sooner,
even before they get there, is better than getting no data.
Back to agenda
Project
3 – Mechanical
and Metallurgical Analysis of Structural Steel
Dr. Frank W. Gayle, WTC Investigation, Project 3 Leader
PRESENTATION (pdf file)
Dr. Gayle presented an update on Project 3 of the WTC Investigation,
Mechanical and Metallurgical Analysis of Structural Steel recovered
from the WTC towers. Dr. Gayle covered four issues. The first
was an overview of the measured mechanical properties of the
recovered steel compared with the requirements as given in
the structural steel design drawings. On average, strengths
were 10 to 15 percent higher than the required values, and
about 13 percent had measured yield strengths below the required
values. NIST has concluded that the strength distributions
are not unexpected for tests of damaged steel, where slight
damage can reduce the measured yield strength.
Dr. Gayle then described a metallographic study of the steel
to determine pieces that may have seen high temperature exposure
from the precollapse building fire. Results were consistent
with the previous paint-condition study. Results were compared
with the fire model predictions of maximum temperatures for
the same pieces of steel.
The last areas covered
were a review of the findings from Project 3 and a description
of the Investigation issue associated
with Project 3. The issue deals with the use of "fire-resistant" steel
in the United States, especially the appropriate measurement
methods to characterize properties, and the codes in the United
States, Japan, and Europe, which tend to encourage or discourage
the use of such steels.
Q: I have a problem
with the statement that the steel collected for the investigation
is adequate. If I were doing an accident
reconstruction, I would’ve been looking for core columns
that were hit by the aircraft. It may be okay from a research
perspective. It should not be stated that it is adequate from
an investigation point of view.
A: It would have been nice to have, but may have been very
hard to find. There is an issue of how the pieces hit would
have survived and how they could be identified.
Q: If you go to the site, you look for pieces of the right
size, etc. NIST never had the opportunity to do this type of
search.
A: The Structural Engineers Association of New York (SEAoNY)
started collecting steel in October of 2001. NIST was a member
of that team. That team had a list of steel to look for. Some
steel had disappeared and was recycled. NIST took over 8 months
before the investigation began. We did not have reconstruction
in mind. That would have been extremely expensive for us to
do. We tried to get all grades of steel. We tried to get pieces
from the impact zone, fire affected pieces, etc. If we had
the authority, we would have been more aggressive.
Q: That’s what I’m saying. Looking down the road
to future incidents, NIST should have the authority to preserve
evidence useful for an investigation.
A: We’ll qualify that statement.
Q: The hypothesis
is that core columns got above 600 ºC.
It would be nice to have pieces of steel to support that hypothesis.
You do have trusses from above the floors of impact?
A: None of the trusses could be identified as to location,
only the truss seats that were considered part of the panels.
Q: Have you analyzed the truss seats?
A: Yes, but the steel for the truss seats was from various
sources, so there was no baseline material for comparison
purposes for metallography.
C: As John Barsom said, the statement is not accurate. The
validity of the model question from yesterday speaks to this
issue. I do not believe that we have enough forensic evidence.
It may be okay to establish steel quality. There was no effort
by the Building Performance Study team to systematically look
at the steel.
C: The use of the term “adequate” needs to be revisited.
There is no core column test to support the hypothesis. The
floors came down, the slabs were pulverized. This was unprecedented.
Exterior columns and core remained. The floors group will attack
this finding.
C: With the low
data points for the yield strength as shown on the slides,
it does not appear to indicate that the steel
meets the specifications. You need to flag the reasons for
these outliers. Compression is a factor. Properties can change
due to compression even if there is no deformation. This needs
to be stated. Fire resistant steel claims by Japan are false.
There is hardly any difference. The difference is in the modeling
done in Japan. These steels would not perform better than U.S.
materials. You need to concentrate on the performance of steel
as it is tested—look at weldability, high-temperature
chrome steels. Also, the cost of such steel may be a factor.
Back to agenda
The Station Nightclub Fire Investigation
Dr. William L. Grosshandler, Chief, Fire Research Division
PRESENTATION (pdf file)
A report on the status of the investigation into The Station
fire was given by Dr. Grosshandler, the lead investigator.
He briefly reviewed the goals and methodology used and stated
that the fact-finding, testing, and analyses had been completed.
Findings were presented for the fire protection systems, materials
involved in the fire, the occupant load and egress from the
building, and public building record-keeping practices. The
key findings included the following:
· A heat detection/fire alarm system was installed in the building
and was activated (sound and strobe) by fire 41 seconds after
ignition. Sprinklers were not installed in the building.
- Exemplar
foam sample purchased by NIST ignited within 10 seconds
when exposed to pyrotechnic device.
- The
energy content of polyurethane foam was estimated to have
been
5 percent of the energy content of wood paneling
in the main area of the nightclub.
- Simulations
show that flames spread rapidly over the foam finish material,
generating 10 megawatts
at the fire's
peak, enough to ignite the wood paneling underneath and adjacent to the
foam.
- The
fire transitioned to a more traditional wood frame building
fire, with steady heat release rate
calculated
to be around 3.5 megawatts.
- The
number of building occupants at the time of fire was reported
to be 440.
- About
two-thirds of the occupants appear to have attempted to
leave through the main entrance in the
front of the building, and many were unsuccessful.
- Windows
in the main bar room and sunroom became secondary routes
of escape once the
main entrance became
impassible, and accounted for over one-third of the successful evacuations.
- The
small number of victims found in the main bar room suggests
that the main bar room exit door
and windows provided open routes of escape for about as
long as it took to reach
untenable
conditions in that area.
- For
more than a minute into the fire, the crowd moved in an
orderly
fashion at an egress rate
estimated to be a bit faster than one person per second through the main entrance
of building.
- Prior
to 1 1/2 minutes into the fire, a pile-up occurred at the
front door, which almost entirely
disrupted flow through that exit.
- Records
were not found of initial building design, and records
of modifications, when located,
lacked sufficient detail to track changes to the structure.
- Neither
historical nor most current use and occupancy permits for
the building
were located;
however, use of The Station was consistent with International Building Code
(IBC) occupancy
classification of "Group
A-2" and NFPA 5000 occupancy
classification "Assembly."
- No
written reports prior to
February 20, 2003, were
located that mentioned foam materials
on the walls of the nightclub, nor the use of pyrotechnics similar to the gerbs
used on the
night of the fire.
The final report was characterized as 90 percent complete.
C: You talk about national and model codes. NIST needs to
look at standards and codes for the use of indoor pyrotechnics.
The NFPA language is weak.
A: NIST will examine. We welcome input.
C: The use of language, for example, isn’t the stage
more of a platform? In addition, the investigation has been
reliant on a newspaper for occupant loads. Access to information
is a big issue.
C: I noticed that the findings did not state the time to ventilation
control. This should be listed as a finding.
A: Some calculations are being rechecked. We didn’t want
to present it as a finding before it was checked.
Q: How long will the report be? Five hundred pages?
A: That is our target.
Q: Do you have a timeline of building permits?
A: Yes. We a have a record of building permits on file.
Q: Do you have any conclusions on compliance with codes?
A: No. No record of being compliant or noncompliant. Statements
on use are based on the current codes.
Q: What code was the building built to?
A: It was built to the Building Officials and Code Administrators
(BOCA) code. History of codes that applied is included in the
report
Q: Was there any intent to do a code analysis to determine
violations?
A: No, that is beyond the scope of the investigation. We are
not looking at compliance versus noncompliance.
C: The situation could be considered unique or one that could
happen in any number of places in this country on any given
night. What was not compliant if anything about the building
that resulted in this incredible outcome? This gets to compliance,
the use of foam, cyanide versus CO yields of foam. What were
the real causes of death? It misses the point if the findings
don’t address these issues.
A: This was just a non-finding. This points to difficulty in
the investigation because records are not readily available
or have not been kept. Maintenance of records is important.
Q: Perhaps we’re missing the point. The certificate of
occupancy may not have been required by the code and historically
is not required for older buildings. The real issue is if the
facility conformed or was it far from compliance.
A: We are not saying that they should or should not have had
a certificate of occupancy. The observation was simply that
the certificate of occupancy was not located. A number of factors
contributed to significant loss of life. This was a building
failure. In the final report we will address those things that
can be done relative to codes, standards, and practice. There
are a lot of issues regarding practice that may come up.
Q: The investigation has been hampered by subservience to
law enforcement. When will the toxicology/forensics results
be available?
A: We have asked that question, but we have not received an
answer.
C (NIST): The important point is that a judicial process is
still under way. NIST will not take any action that would influence
the ability of any person to get a fair trial.
C: My concern goes to Phil’s question: if materials were
illegal, this is an important issue. Should we wait to report?
A: The facts are clear as to how the fire started and progressed.
Code violation is not relevant to our investigation. Code changes
are what we need to consider.
C: If we can’t provide conclusions, we’re not doing
our job.
C (NIST): We are not here to interpose ourselves between people
and the judicial process. We will try to recommend things that
will make people safer.
C: Many organizations have already jumped to conclusions without
facts. I hoped the report would address the context of how
this building was being operated and whether the event would
have occurred in the same way if the codes were being complied
with. I’m all for making buildings safer, but not for
piling on additional regulations that people ignore when they
already ignore existing regulations.
Q (NIST): Could you elaborate on your analysis? Are you suggesting
that the foam material should not have been there, or are you
suggesting something else? What is your reading of the situation?
Q: I have not done a thorough analysis, but I have looked at
a couple of the standards to try to find out whether the occupancy
of that particular building in that particular configuration
would have been permitted under various codes. Would that have
been a permitted use and would we have expected to find a certificate
of occupancy?
C: I simply have to rest on the fact that we are in the middle
of a judicial process. One of the difficulties that NIST has
is that there are occasionally going to be criminal proceedings
underway that we have to find ways to coexist with.
Q: Why did fire inspectors never identify the foam plastic
as an issue? A reasonable fire inspector would have raised
a question about the foam. Do we have any idea why they never
identified it on the records that you did find?
A: No.
NCST Advisory Committee Business
In this portion of the meeting, all discussion, unless otherwise
noted, is by the Advisory Committee members. The first item
discussed was the annual report that the Committee is required
to provide to Congress, through the NIST director and the Secretary
of Commerce. Mr. Paul Fitzgerald, the chair person, had produced
a draft outline of the annual report for all members to review.
Dr. Hanson asked for feedback on the draft outline.
Q: What is the timeline for releasing the report?
A: Individuals with leadership roles should have a draft available
and concurred to by the other members by the November meeting.
C: Project leaders prepare drafts for their areas. When do
they provide to other members for review prior to the next
meeting?
A (NIST): Paul Fitzgerald just wanted to have all the information
available for the next meeting; we did not discuss the timeline.
Q: Should we provide our drafts to other members a week ahead
of the November meeting to allow time for review?
C (NIST): A week ahead would be great. November 15th would
be great. Paul is doing boilerplate pieces.
C: To clarify, except where your name is underlined, Paul
Fitzgerald is taking the lead on the other sections.
C: Authors are not identified for all sections. For example,
no assignment has been made for investigation of mass fires
and urban-wildland interface fires.
C: That is a topic for the November meeting. The rest of the
day will be focused on issues and recommendations.
C: I suggest that you pass on to Paul Fitzgerald that he have
a draft report available for review by the next meeting. The
November meeting is the last chance for discussion before the
report goes out.
Q: Is there an outline for the chapters?
A: No. Paul Fitzgerald wanted to make clear that we should
not parrot NIST recommendations. The report should contain
the Advisory Committee perception of the process and successes.
C (NIST): November 15 will be the deadline for all submittals
by Committee members.
The Committee then discussed the next meeting.
Q: The next meeting date is November 22. I would like a full
day meeting. Does this present a travel issue? I suggest 8
a.m. to 6 p.m.
C (NIST): The thought was that findings would be presented
in the October meeting. Only recommendations would be presented
in the November meeting.
Q: I recommend closing the meeting. Is that correct Mike [Rubin]?
C (NIST): If you’re giving us consensus advice, I would
prefer an open meeting. Closed meetings are generally used
to protect proprietary information. I’m not sure we are
describing a closed meeting.
C: I prefer an open meeting. Personally, I recommend that the
meeting be open.
C: There will be very little new material. It will be a mastication
of material; distilled to recommendations.
C (NIST): We also will not be covering the Rhode Island investigation
at the November meeting. The focus of the November meeting
will be on recommendations resulting from the WTC investigation.
Q: We’ve heard some new information today. We haven’t
seen the overall direction and backup information. Are we going
to have that between now and the November meeting?
A (NIST): The report is not tied to the November meeting. It
is still a work in progress. It will be more of a narrative
style report. Program reports will contain the detailed technical
information. The main report will be more broadly accessible.
Q: I have a question
on the list of reports. Every document has the same publication
date. That is not the way I would
normally do things. For example, the ceiling tile system test
report was done in the fall of 2003. There is no reason why
this report should not be completed and out on the street.
Shouldn’t supporting documents be released separately?
A (NIST): Your comments make sense. However, the staff is conducting
all the technical work first, writing second. It is a logistics
and resource issue. As soon as reports are written and reviewed,
they go to the Advisory Committee for review. They probably
will all be released at the same time.
Q: Some reports are contractor reports. Why do contractor
reports have NIST authors?
A (NIST): We are not issuing them as contractor reports. NIST
takes full ownership. In many cases, we have actively led the
work done by the contractors in an interactive team setting.
We have listed both NIST authors and contractor authors as
appropriate to reflect the work done.
Q: Can we do the November meeting in a single day?
A (NIST): We could add a second day if you want.
C: There are seven or eight sets of issues that may result
in recommendations, and 2 to 3 hours for resolving the annual
report. It seems like too much for a single day.
C (NIST): The decision is up to the Advisory Committee.
C: Some of us made reservations early to avoid the Thanksgiving
rush.
C (NIST): We have the rest of today to give input on issues.
These help shape the recommendations. Input to the Committee
annual report can also be worked via email beforehand.
C: We need to allow at least 2 hours for the Committee annual
report.
C: In our report last year, we recommended a fixed pot of
funding to allow NIST to respond to a disaster. The rule says
48 hours and available funds to respond. I volunteer to strengthen
the recommendation in the report.
Q: Are we targeting the right audience? Congress is responsible
for the funding but doesn’t the Office of Management
and Budget (OMB) also have a responsibility for who gets money
and when? Should there be another document sent to another
agency to convince them this is something we need to do?
C: We have to first convince the NIST director, then the Secretary
of Commerce, then OMB. The Committee doesn’t have the
authority to short circuit the process.
Q: Funding is definitely an issue. Reorganization is also an
issue. Have you thought about the organization you would put
in place if you had funding?
A (NIST): We have discussed the issue. We have not yet put
anything on paper. Implementation will be a function of resources.
Q: I prefer an open meeting. I have no reservation about criticizing
work in an open meeting. If the meeting is open does that mean
we have to have the 5 minute public presentations?
A (NIST): We don’t have to have an open public comment
session. The entire subject could be the recommendations.
C (NIST): There are legal criteria that must be met to close
a meeting. Decide what you want to do, and we can compare that
with what the statute requires.
C: What I’m hearing is that there is no reason to close
the next meeting.
C: Part of the concern was in leading up to this October meeting.
Open meetings are okay as long as the Committee generates the
agenda and decides on the use of time. That way we can run
meetings more efficiently so that the Committee can be more
effective. Just sitting here being talked to does not generate
a positive effect.
C: The consensus is that we will next meet on November 22,
2004, from 8 a.m. to 6 p.m. The meeting will be open.
Motion to adjourn the meeting was agreed to.
The open session of the meeting was adjourned at 11 a.m.
ATTENDANCE
Advisory
Committee
Barsom, John
DiNenno,
Philip
Collins, David
Corbett,
Glenn
Hanson, Robert (acting chair)
Thornton,
Charles
Williams, Forman
Hill,
James, Designated Federal Official NIST
Management
Bement, Arden, Director
Heyman, Matthew, Chief of Staff
Office
of the General Counsel
Burkhardt,
Craig
Rubin, Michael
Lieberman, Melissa
Public
and Business Affairs
Newman, Michael |
WTC
Investigation
Averill, Jason
Banovic, Stephen
Bukowski, Richard
Carino, Nicholas
Foecke,
Timothy
Fritz, William
Gayle, Frank
Gann, Richard
Gross, John
Kuligowski, Erica
Lawson, James R.
Luecke, William
Lew, H.S.
McAllister, Therese
McGrattan, Kevin
Nelson, Harold
Peacock, Richard
Pitts, William
Prasad, Kuldeep
Rehm, Ronald
Sadek, Fahim
Simiu, Emil
Starnes, Monica
Sunder, Shyam
Vettori, Robert
The
Station Nightclub Investigation
Grosshandler, William
Kerber, Stephen
Kuntz, Ken, U.S. Fire Administration
|
WTC
Administrative Support
Cauffman, Stephen
Cavanaugh, Sydel
DiMarzio, John
Sawyer, Cheri
Soverow, Walter
Public
Commentors
Kuchnicki, Richard, International Code Council
Pauls,
Jake, Consulting Services in Building Use and
Safety
Polk, Robert, National Association of State Fire Marshals
Quintiere, James, University of Maryland
Regenhard,
Sally, Skyscraper Safety Campaign
|
World
Trade Center homepage
Construction
Safety Investigation homepage
Created:
07/22/2004
Updated:
01/24/2005
|
