Proposed Plan
National Institute of Standards and Technology
National Building and Fire Safety Investigation of
the World Trade Center Disaster
Goals:
·
To investigate
the building construction, the materials used, and the technical conditions
that combined to cause the World Trade Center (WTC) disaster.
·
To serve as the
basis for:
o
Improvements in
the way buildings are designed, constructed, and used; and
o
Improved tools,
guidance for industry and safety officials, revisions to codes and standards,
and improved public safety.
Objectives:
The primary objectives of
the NIST-led technical investigation of the WTC disaster are to:
·
Determine why and how the World Trade Center
buildings collapsed;
·
Determine why the injuries were so low or high
depending on location, including all technical aspects of fire protection,
response, evacuation, and occupant behavior and emergency response;
·
Determine whether or not state-of-the-art procedures
and practices were used in the design, construction, operation, and maintenance
of the World Trade Center Buildings; and
·
Identify building and fire codes, standards, and
practices that warrant revision.
Source of Information for Plan
Development:
The
formulation of the NIST investigation plan will draw on several sources of
information. These include the FEMA/ASCE
Building Performance Assessment (BPAT) study, NIST experts in building and fire
safety, external experts and groups (industry and academia), and the
public-at-large. NIST will hold a public
meeting to gather information that will help guide its investigation, including
public comments on the proposed NIST investigation plan[1]. The refined plan will be made available for
public comment before it is adopted as final.
Program Context for the Investigation:
The proposed NIST
response plan consists of three key program elements – including an
investigation – to be conducted in parallel. These are:
·
First, a
24-month building and fire safety investigation into the collapse of
the Twin Towers (WTC 1 and 2) and WTC 7.
The goal of this program element is to investigate the building
construction, the materials used, and the technical conditions that combined to
cause these disasters following the initial impact of the aircraft. While WTC 4, 5,and 6 will not be investigated
specifically in this phase, what is learned in examining WTC 1, 2 and 7 is
expected to benefit buildings of all designs.
·
Second,
a multi-year research and development (R&D) program to provide the
technical basis to support improved building and fire codes, standards, and
practices. This program element
addresses work in critical areas such as structural fire safety, prevention of
progressive collapse, and equipment standards for first responders. It includes BPAT recommendations for WTC 3,
4, 5, and 6, Bankers Trust, and peripheral buildings as well as recommendations
for future studies to address specific issues of broader scope not covered by
the BPAT. The program outputs and
recommendations will support the voluntary consensus process that is used to
develop building and fire codes and standards in the United States.
·
Third, an
industry-led dissemination and technical assistance program (DTAP) that will
provide practical guidance and tools to better prepare facility owners,
contractors, designers, and emergency personnel to respond to future disasters.
The DTAP will also be an important complement to the R&D effort in gaining
acceptance of proposed changes to practice, standards, and codes. This program element addresses BPAT
recommendations for training and education of stakeholders.
The response plan is different
from and responsive to the BPAT efforts.
The plan addresses all major recommendations contained in the BPAT
report[2]. NIST has also identified other critical
issues that need study, especially in areas that impact life safety and
engineering practice.
Scope and Rationale for Investigation:
NIST agrees with the BPAT
recommendations that additional studies of the Twin Towers and WTC 7 should be
conducted. The NIST investigation – one
component of the proposed NIST response plan – will focus on these
buildings. The results of such an
investigation could lead to major changes in both U.S. building and fire codes and in engineering
practice, despite the unique design features or circumstances under which the
buildings collapsed. The lessons to be
derived from such an investigation will be applicable to a broad range of
buildings types, not just the specific buildings that are studied. The following examples are illustrative:
The Twin Towers and WTC 7
are the only known cases of total structural collapse where fires played a
significant role. These disasters
provide a unique source of information to understand the complexities
associated with the dynamics of building fires and the collapse vulnerability
of structures to fires. The
investigation expects to analyze that information to validate generally
applicable methodologies for use in fire safety design and retrofit of
structures, and to evaluate the performance of fireproofing materials and connections
used in steel structures.
In addition, these building
disasters provide a unique source of information to study:
·
The safety and
performance of open-web steel trussed joists under fires. This type of trussed joist is used widely in
floor and roof systems for commercial and institutional buildings
nationwide.
·
New mechanisms –
not considered previously – that could initiate progressive collapse in
buildings as a result of fires and impact loads, and the critical role of
pivotal components such as transfer girders and floor diaphragms.
·
The mechanical
and metallurgical behavior of many different grades of structural steel under
fires using steel recovered from the WTC site that is being stored at NIST.
There are equally important
lessons for life safety – which were outside the scope of the BPAT study.
·
Firefighting
technologies and practices for tall buildings, including occupant behavior,
evacuation, emergency response, and the performance of built-in fire protection
systems such as sprinklers and fire alarms.
·
The control of
fire spread in buildings with large open floor plans, and the effectiveness of
compartmentation as a means to isolate fires in such buildings.
There are also important lessons
for engineering practice that were not the focus of the BPAT study.
·
The performance of the design, construction, and
approval processes used to assure safety whenever an innovative structural
system is used or there is a need for variances from building and fire codes –
and whether such practices are adequate to detect and remedy inherent
vulnerabilities.
·
The provision of
adequate structural reserve capacity to accommodate abnormal loads such as
blast, impact, and accidental fires – especially those that can be anticipated
prior to construction – balanced properly against the need to achieve design
efficiency.
Technical
Approach:
The technical approach of the NIST investigation will
include the following phases over an estimated 24-month period:
•
Identification of
Technical Issues and Major Hypotheses Requiring Investigation: opportunity for public input (e.g., open
meeting; website; Federal Register notice) in developing investigation plan;
convene expert panels to solicit input (experts in structural and fire
protection engineering; experts in construction, maintenance, operation and
emergency response procedures of tall buildings); findings and recommendations
of FEMA-funded study and technical issues identified by other experts; analyze
inputs and establish priorities; review by Federal Advisory Committee.
•
Data Collection: inputs from the Port Authority of New York
and New Jersey (PANYNJ), local authorities, consultants, and contractors; data
and information collected by the FEMA/ASCE BPAT study; building and fire
protection design calculations, records, plans, and specifications;
construction, maintenance, operation records, building renovations and
upgrades; video and photographic data; field data; interviews; emergency
response records including audio communications; and other records.
•
Analysis and
Comparison of Building and Fire Codes and Practices: analysis and
comparisons of codes and standards then and now, and specifications used for
WTC buildings; review and analysis of practices used for design, construction,
operation, maintenance, repair, renovations, and upgrades.
Collection and
Analysis of Forensic Evidence: structural steel,
material specimens and other forensic evidence to the extent they have been
collected or are otherwise available; metallurgical and mechanical analysis of steel to evaluate quality and estimate
maximum temperatures; analysis of fire and elevator control panels
•
.
•
Modeling,
Simulation, and Scenario Analysis: aircraft impact on structures and estimate
damages to interior and core structure and residual capacities; role of jet
fuel and building contents in resulting fire; fire dynamics and smoke movement;
thermal effect on structures and the effect of fireproofing; effect of fire,
connections, flooring system, core and exterior columns on structural response
and vulnerability; occupant behavior and response including influence of
communications and barriers to egress; evacuation issues including egress,
control/fire panels, emergency response, and communications; fire protection
system design and vulnerability; competing hypotheses for structural collapse
including evaluation of system vulnerability to progressive collapse; bounds
for probable collapse mechanisms.
•
Testing to
Re-Create Scenarios and Failure Mechanisms:
small and some real-scale re-creation tests to provide additional data
and verify simulation predictions, especially effect of fires (e.g., use and
adequacy of standard fire ratings, behavior of connections and assemblies).
•
Technical Findings and
Recommendations: preparation of interim and
final reports; review by established NIST Editorial Review Board; augmented
NIST review to include senior management, legal, and public affairs; review by
Federal Advisory Committee; public comment period; finalize and disseminate via
published reports, web, and media.
•
Dissemination and Deployment of Findings: develop and disseminate proposed changes to codes and
standards based on findings; participate with industry in their adoption and
acceptance into codes and standards.
At this point, the NIST
investigation plan anticipates organizing around 10 project areas that would
provide the focus for the technical work.
These include: (1) aircraft impact analysis and damage prediction; (2)
forensic analysis of structural steel; (3) analysis of built-in fire protection
systems; (4) prediction of thermal environment; (5) structural fire response
and vulnerability; (6) structural collapse vulnerability and mechanisms; (7)
occupant behavior and egress; (8) fire service technologies and guidelines; (9)
fire codes and standards; (10) analysis of building codes and practices. A GANTT chart with key sub-tasks for these
projects and proposed timelines is attached.
Technical
Expertise:
The proposed NIST investigation
will use world-class technical expertise from both within and outside
NIST. External experts will be drawn
from academia and practice and used on an as needed basis in various phases of
the investigation. Many of these experts
may well have contributed to the BPAT study.
Federal
Advisory Committee:
NIST proposes to
charter a Federal Advisory Committee to guide all aspects of the NIST
investigation. The Committee will
provide advice on scope, approach, work plan, and schedule; review and provide
advice on results, findings, and recommendations; and review and provide advice
on interim and final technical reports.
Committee meetings will be announced in the Federal Register. Members of the Panel will be recognized for
distinguished professional service, possess broad technical expertise and
experience, and have a reputation for independence, objectivity, and
impartiality. Members of this committee
will be selected to avoid conflicts of interest – they cannot represent parties
that may be affected directly, participate in the conduct of the investigation,
or participate in litigation involving the World Trade Center disaster. The primary focus of the Panel will be to
ensure that the right things are being done and to provide an independent
review of the investigation.
NIST
Secretariat:
NIST will establish a secretariat to coordinate NIST-level
activities in support of the proposed investigation and to maintain ongoing
liaison with the Congress, the public, and the media. NIST recognizes that there will be
significant public and media interest in the investigation. NIST will assign a spokesman to provide press
announcements and media briefings during the course of the investigation. NIST will also provide information via
reports and briefings to Congress at its request. The secretariat will include representatives
of the Building and Fire Research Laboratory, Congressional and Legislative
Affairs, Budget, Public and Business Affairs, NIST Counsel, Program Office,
Acquisition and Logistics, and Occupational Health and Safety.
Liaison with the Professional Community, the Public,
and Local Authorities:
NIST will maintain ongoing
liaison with the professional community, the public, and local authorities over
the course of the investigation through briefings, presentations, and
opportunity for comment on key investigation reports. NIST will assign a
special liaison to interact with the families of building occupants and first
responders. NIST recognizes the vital
role that those individuals and groups have to play in providing input on the
scope of the proposed NIST investigation.
We also understand that it is appropriate and important to keep these
families and organizations informed about the progress of the proposed
investigation.
Guiding
Principles:
·
Independent and objective technical investigation
that is fully informed of the concerns and issues of all interested parties.
·
Open and inclusive process in planning and conducting
investigation, and in publishing findings and recommendations.
·
Focus on fact-finding, validating/verifying existing
knowledge, and creating new technical and/or scientific knowledge for the
purpose of deriving lessons to improve practice, standards, and codes and to
reduce future risks.
·
Non-technical issues outside scope: No findings of fault. No determination as to negligence of any individual
or organization.
Impact, Outcomes, and Consequences:
The implementation of the results
of the investigation will be critical to restore public confidence by making
tall buildings safer nationwide, enhance the safety of fire and emergency
responders, and better protect building occupants and property in the
future. In addition, the investigation will be
valuable in establishing the probable technical causes of the disaster,
deriving the lessons from the WTC disaster, and identifying needed improvements
to building and fire standards, codes, and practices and to the safety of tall
buildings nationwide.
Specifically, the NIST investigation will provide an
authoritative technical account of:
·
Why and how the World Trade Center buildings
collapsed, including the probable technical causes of the disaster.
·
Why the injuries and fatalities were so low or high
depending on location, including all occupant behavior and response and
evacuation procedures actually experienced.
·
Whether or not then-current procedures were used in
the design, construction, operation, and maintenance of the WTC buildings.
The NIST results will be supported by careful and
detailed analytical and experimental work.
The results of the investigation will also underpin
and guide future work to develop and disseminate immediate guidance and tools
to assess and reduce vulnerabilities, and produce the technical basis for
cost-effective changes to national practices and standards. A private sector coalition – representing the
key industry, standards, codes, and professional organizations – has worked
with NIST to establish the response plan (see page 1) to meet these longer-term
needs. The goal of the longer-term
program is to produce cost-effective retrofit and design measures and operational
guidance for building owners and emergency responders.
The specific consequences of
not carrying out this investigation and the broader response plan include: loss of valuable perishable data that must be
collected and archived immediately, incomplete and lack of objective
assessments of building failures and lessons for the future, unknown
vulnerability of existing building stock and lack of vulnerability assessment
tools, lack of operational guidance for building owners and emergency responders,
continuing risk in the performance of fire protection systems and technical
barriers to innovation, unreliable test methods, outdated design codes and
standards for new construction and lack of information to provide similar
guidance to retrofit existing buildings, and risks associated with ad hoc and
prescriptive changes to building codes that lack technical basis.
Performance Outputs for
WTC Investigation
|
National Building and Fire Safety Investigation of
the World Trade Center Disaster |
|
|
Technical Area |
Outputs |
|
Identification
of Technical Issues and Major Hypotheses |
·
Public Meetings to gather information to guide plan
for NIST investigation. ·
Report(s) on NIST Investigation Plan Approach and
Process. |
|
Analysis
of Building and Fire Codes and Practices |
·
Report(s) on Analysis of Building and Fire Codes
and Practices. |
|
Aircraft
Impact Analysis and Damage Prediction |
·
Report(s) on Aircraft Impact Analysis and Damage
Prediction. |
|
Forensic
Analysis of Structural Steel |
·
Report(s) on Forensic Analysis of Structural Steel. |
|
Analysis
of Built-In Fire Protection Systems |
·
Report(s) on Analysis of Built-In Fire Protection
Systems. |
|
Prediction
of Thermal Environment |
·
Report(s) on Prediction of Thermal Environment. |
|
Structural
Fire Response and Vulnerability |
·
Report(s) on Structural Fire Response and
Vulnerability. |
|
Structural
Collapse Vulnerability and Mechanisms |
·
Report(s) on Structural Collapse Vulnerability and
Mechanisms. |
|
Occupant
Behavior and Egress |
·
Report(s) on Occupant Behavior and Egress. |
|
Fire
Service Technologies and Guidelines |
·
Report(s) on Fire Service Technologies and
Guidelines |
|
Fire
Codes and Standards |
·
Report(s) on Elevator and Fire Resistance
Standards. |
|
Technical
Findings and Recommendations |
·
Interim and Final Reports on the Technical Findings
and Recommendations of the Investigation, including probable technical causes
of the disaster. |
|
Dissemination
and Deployment of Findings |
·
Dissemination and Deployment of Findings via
proposed standards and codes changes and participation with industry in their
adoption and acceptance into codes and standards. |