NIST NCSTAR1-3B

Federal Building and Fire Safety Investigation of the

World Trade Center Disaster

Steel Inventory and Identification

Stephen W. Banovic

National Institute of Standards and Technology • Technology Administration • U.S. Department of Commerce

NIST NCSTAR1-3B

Federal Building and Fire Safety Investigation of the

World Trade Center Disaster

Steel Inventory and Identification

Stephen W. Banovic

Materials Science and Engineering Laboratory

National Institute of Standards and Technology

September 2005

U.S. Department of Commerce

Carlos M. Gutierrez, Secretary

Technology Administration

Miclielle O'Neill, Acting Under Secretary for Technology

National Institute of Standards and Technology

William Jeffrey, Director
Disclaimer No. 1

Certain commercial entities, equipment, products, or materials are identified in this document in order to describe a procedure or concept adequately or to trace the history of the procedures and practices used. Such identification is not intended to imply recommendation, endorsement, or implication that the entities, products, materials, or equipment are necessarily the best available for the purpose. Nor does such identification imply a finding of fault or negligence by the National Institute of Standards and Technology.

Disclaimer No. 2 The policy of NIST is to use the International System of Units (metric units) in all publications. In this document,

however, units are presented in metric units or the inch-pound system, whichever is prevalent in the discipline.

Disclaimer No. 3

Pursuant to section 7 of the National Construction Safety Team Act, the NIST Director has determined that certain evidence received by NIST in the course of this Investigation is "voluntarily provided safety-related information" that is "not directly related to the building failure being investigated" and that "disclosure of that information would inhibit the

voluntary provision of that type of information" (15 USC 7306c).

In addition, a substantial portion of the evidence collected by NIST in the course of the Investigation has been

provided to NIST under nondisclosure agreements.

Disclaimer No. 4

NIST takes no position as to whether the design or construction of a WTC building was compliant with any code

since, due to the destruction of the WTC buildings, NIST could not verify the actual (or as-built) construction, the

properties and condition of the materials used, or changes to the original construction made over the life of the

buildings. In addition, NIST could not verify the interpretations of codes used by applicable authorities in determining

compliance when implementing building codes. Where an Investigation report states whether a system was

designed or installed as required by a code provision, NIST has documentary or anecdotal evidence indicating

whether the requirement was met, or NIST has independently conducted tests or analyses indicating whether the requirement was met.

Use in Legal Proceedings

No part of any report resulting from a NIST investigation into a structural failure or from an investigation under the

National Construction Safety Team Act may be used in any suit or action for damages arising out of any matter mentioned in such report (15 USC 281a; as amended by P.L. 107-231).

National Institute of Standards and Technology National Construction Safety Team Act Report 1-3B

Natl. Inst. Stand. Technol. Natl. Constr. Sfty. Tm. Act Rpt. 1-3B, 112 pages (September 2005)

CODEN: NSPUE2

U.S. GOVERNMENT PRINTING OFFICE

WASHINGTON: 2005

For sale by the Superintendent of Documents, U.S. Government Printing Office

Internet: bookstore.gpo.gov — Phone: (202) 512-1800 — Fax: (202) 512-2250

Mail: Stop SSOP, Washington, DC 20402-0001
Abstract

As a result of the recovery efforts of the Structural Engineers Association of New York, Federal

Emergency Management Agency/American Society of Civil Engineers, and the National Institute of

Standards and Technology (NIST), NIST possesses 236 structural steel elements from the World Trade

Center (WTC) buildings. These samples include full exterior column panels, core columns, portions of

the floor truss members, channels used to attach the floor trusses to the interior columns, and other

smaller structural components (e.g., bolts, diagonal bracing straps, aluminum fa9ade). Many significant

pieces were recovered from the impact and fire-affected floors. Additionally, the recovered structural elements have yielded sufficient representative samples, with respect to the detennination of the quality

and mechanical properties of the steel, for all 12 grades of exterior panel material, 2 grades of the core column material (representing 99 percent, by total number, of the columns), and both grades for the floor

truss material. The lack of WTC 7 steel precludes tests on actual material from the structure; however,

WTC 7 was constructed of three grades of conventional steel (36 ksi, 42 ksi, and 50 ksi), and hterature

values may be used to estimate properties.

Keywords: Identification, inventory, recovered, steel, structural elements, World Trade Center.

NISTNCSTAR 1-3B, WTC Investigation iii
Abstract

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iv NISTNCSTAR 1-3B, WTC Investigation
Table of Contents

Abstract iii

List of Figures vii

List of Tables ix

List of Acronyms and Abbreviations xi

Preface xiii Acknowledgments xxiii

Executive Summary xxv

Chapter 1 Introduction 1

1 . 1 Purpose of Report 1

1.2 Scope of Report 1

Chapter 2 Background Information Related to Recovery of WTC Structural Steel 3

Chapter 3 Structural Elements Recovered from the WTC Buildings 5

3.1 Present Location and Labeling of Structural Steel Elements 5

3.2 Identification of WTC Structural Steel Elements 7

Chapter 4

Structural Steel Elements of Special Importance 47

4. 1 Samples Located in or Around the Floors Impacted by the Airplane 47

4.2 Samples Representing the Various Types of Steel Specified in the Design Drawings 49

Chapters

Summary 55

Chapter 6 References 57

Appendix A

Data on Recovered WTC Steel

NISTNCSTAR 1-3B, WTC Investigation ^
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VI NISTNCSTAR 1-3B, WTC Investigation
List of Figures

Figure P-1. The eight projects in the federal building and fire safety investigation of the WTC

disaster xv

Figure 3-1. Characteristic "overall" view of the samples taken for each piece received. Sample

shown here is C-14 6

Figure 3-2. Location of the exterior panels recovered from the top third of WTC 1 and WTC 2 9

Figure 3-3. Example of stampings on the interior base of the middle column for each panel 1

1

Figure 3-4. Example of stampings placed on one end of a core column 12

Figure 3-5. (a) Example of stamping placed on flange indicating the column type (120), and (b)

schematic indicating the various plates corresponding to Table 3-5 13

Figure 3-6. (a) Characteristic stenciling found on the lower portions of the exterior column panels

for sample C-14. (b) Characteristic stenciling found on an interior core column for sample B-6152 15

Figure 3-7. Schematic showing derrick divisions that hoisted the specific columns for (a) WTC 1 and (b) WTC 2. The 'V signifies the information that was not readable 16

Figure 3-8. Schematic showing the sample M-10 as two separate exterior column panels, M-lOa

and M- 10b 25

Figure 3-9. Schematics displaying the various types of exterior column panels 27

Figure 3-10. Exterior column panel maps indicating the portion of the specific exterior column

panel section recovered from WTC 1 28

Figure 3-1 1. Exterior column panel maps indicating the portion of the specific exterior column

panel section recovered from WTC 2 35

Figure 3-12. Core columns recovered from WTC 1. a) B-101 1 (508A: 51-54), lower 2 ft to 3 ft of

built-up box column, b) B-6152-1 (803A: 15-18), lower 3 ft of built-up box column 39

Figure 3-13. Core columns recovered from WTC 2. a) C-88a (801B: 80-83), lower 16 ft of built- up box column and C-88b (80 IB: 77-80), upper 8 ft of built-up box column 43

Figure 3-14. Structural element composed of three wide flange sections bohed together. The

component was found to be from the framed floor area outside of the core on the 107th floor of WTC 1 (sample was C-26) 45

Figure 4-1 . Interpreted column damage, from photographic evidence, to WTC 1 , with overlay of

samples in NIST's possession. Samples shown represent recovered portions. Core

columns 603 and 605 are in the second row from the north face of WTC 1 48

Figure 4-2. Interpreted column damage, from photographic evidence, to WTC 2, with overlay of

samples in NIST's possession 49

NISTNCSTAR 1-3B, WTC Investigation vii
List of Figures

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vni NISTNCSTAR 1-3B, WTC Investigation
List of Tables

Table P-1 . Federal building and fire safety investigation of the WTC disaster xiv

Table P-2. Public meetings and briefings of the WTC Investigation xvii

Table 3-1. Identified exterior column panel pieces from WTC 1 and WTC 2 8

Table 3-2. Partially identified exterior column panel from WTC 1 or WTC 2 9

Table 3-3. Identified pieces of core column material from WTC 1 and WTC 2 10

Table 3-4. Other built-up box columns and wide flange sections from WTC 1 and WTC 2 with

ambiguous stampings and/or markings 10

Table 3-5. Examples of column types with corresponding plate gauges 14

Table 3-6. Specified and observed minimum yield strengths for positively identified exterior

column panels 1

8

Table 3-7. Specified and observed column types for positively identified exterior column panels 19

Table 3-8. Specified minimum yield strengths from WTC 1 and WTC 2, along with the observed

stampings, used to positively identify some exterior column panels 20

Table 3-9. Specified column types of exterior panels from WTC 1 and WTC 2, along with the

observed stampings, used to positively identify some exterior column panels 21

Table 3-10. Information used to determine the identificafion of exterior panel ASCE-2 22

Table 3-11. Information used to determine the identification of exterior panel M-2 24

Table 4-1 . Listing of recovered exterior column panels with specified minimum yield strengths

and thickness for columns and spandrels 51

Table 4-2. Strength/gauge combinations of perimeter columns recovered by NIST 52

Table 4—3. Strength/gauge combinations of spandrels recovered by NIST 53

NISTNCSTAR 1-3B, WTC Investigation ^
List of Tables

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X NISTNCSTAR 1-3B, WTC Investigation
List of Acronyms and Abbreviations

Acronyms

AISC American Institute of Steel Construction

ASCE American Society of Civil Engineers

ASTM ASTM International

BOCA Building Officials and Code Administrators

BOCA/BBC BOCA Basic Building Code

DTAP dissemination and technical assistance program

FEMA Federal Emergency Management Agency

CMS, LLP Gilsanz Murray Steficek, LLP

JFK John F. Kennedy International Airport

LERA Leslie E. Robertson Associates

LES Large Eddy Simulation

NIST National Institute of Standards and Technology

P.L. Public Law

PANYNJ Port Authority of New York and New Jersey

PONYA Port of New York Authority

R&D research and development

SEAoNY Structural Engineers Association of New York

use United States Code

WF wide flange (a type of structural steel shape now usually called a W-shape). ASTM A 6

defines them as "doubly-symmetric, wide-flange shapes with inside flange surfaces that

are substantially parallel."

WTC World Trade Center

WTC 1 World Trade Center 1 (North Tower)

WTC 2 World Trade Center 2 (South Tower)

WTC 7 World Trade Center 7

NISTNCSTAR 1-3B, WTC Investigation xi
List of Acronyms and Abbreviations

Abbreviations

ft foot

Fy yield strength (AISC usage)

in. inch -

kg kilogram

ksi 1 ,000 pounds per square inch

m meter

Xll NISTNCSTAR 1-3B, WTC Investigation
Preface

Genesis of This Investigation

Immediately following the terrorist attack on the World Trade Center (WTC) on September 1 1, 2001 , the Federal Emergency Management Agency (FEMA) and the American Society of Civil Engineers began

planning a building perfonnance study of the disaster. The week of October 7, as soon as the rescue and

search efforts ceased, the Building Performance Study Team went to the site and began its assessment. This was to be a brief effort, as the study team consisted of experts who largely volunteered their time

away from their other professional commitments. The Building Performance Study Team issued its report in May 2002, fulfilling its goal "to determine probable failure mechanisms and to identify areas of

future investigation that could lead to practical measures for improving the damage resistance of buildings

against such unforeseen events."

On August 21, 2002, with funding from the U.S. Congress through FEMA, the National Institute of

Standards and Technology (NIST) announced its building and fire safety investigation of the WTC

disaster. On October 1, 2002, the National Construction Safety Team Act (Public Law 107-231), was

signed into law. The NIST WTC Investigation was conducted under the authority of the National

Construction Safety Team Act.

The goals of the investigation of the WTC disaster were:

• To investigate the building construction, the materials used, and the technical conditions that contributed to the outcome of the WTC disaster.

• To serve as the basis for: - Improvements in the way buildings are designed, constructed, maintained, and used; - Improved tools and guidance for industry and safety officials; - Recommended revisions to current codes, standards, and practices; and - Improved public safety.

The specific objectives were:

1. Determine why and how WTC 1 and WTC 2 collapsed following the initial impacts of the

aircraft and why and how WTC 7 collapsed;

2. Determine why the injuries and fatalities were so high or low depending on location,

including all technical aspects of fire protection, occupant behavior, evacuation, and

emergency response;

3. Determine what procedures and practices were used in the design, construction, operation,

and maintenance of WTC 1,2, and 7; and

4. Identify, as specifically as possible, areas in current building and fire codes, standards, and

practices that warrant revision.

NISTNCSTAR 1-3B. WTC Investigation xiii
Preface

NIST is a nonregulatory agency of the U.S. Department of Commerce's Technology Administration. The

purpose of NIST investigations is to improve the safety and structural integrity of buildings in the United

States, and the focus is on fact finding. NIST investigative teams are authorized to assess building

perfomiance and emergency response and evacuation procedures in the wake of any building failure that has resuhed in substantial loss of life or that posed significant potential of substantial loss of life. NIST

does not have the statutory authority to make findings of fault nor negligence by individuals or

organizations. Further, no part of any report resulting from a NIST investigation into a building failure or from an investigation under the National Construction Safety Team Act may be used in any suit or action

for damages arising out of any matter mentioned in such report (15 USC 281a, as amended by Pubhc

Law 107-231).

Organization of the Investigation

The National Construction Safety Team for this Investigation, appointed by the then NIST Director, Dr. Arden L. Bement, Jr., was led by Dr. S. Shyam Sunder. Dr. William L. Grosshandler served as Associate Lead Investigator, Mr. Stephen A. Cauffman served as Program Manager for Administration,

and Mr. Harold E. Nelson served on the team as a private sector expert. The Investigation included eight

interdependent projects whose leaders comprised the remainder of the team. A detailed description of

each of these eight projects is available at http://wtc.nist.gov. The purpose of each project is summarized

in Table P-1, and the key interdependencies among the projects are illustrated in Fig. P-1.

Table P-1. Federal building and fire safety investigation of the WTC disaster.

Technical Area and Project Leader Project Purpose

Analysis of Building and Fire Codes and

Practices; Project Leaders: Dr. H. S. Lew

and Mr. Richard W. Bukowski

Document and analyze the code provisions, procedures, and

practices used in the design, construction, operation, and

maintenance of the structural, passive fire protection, and

emergency access and evacuation systems of WTC 1, 2, and 7. Baseline Structural Perfonnance and

Aircraft Impact Damage Analysis; Project Leader: Dr. Fahim H. Sadek

Analyze the baseline perfonnance of WTC 1 and WTC 2 under

design, service, and abnonnal loads, and aircraft impact damage on

the structural, fire protection, and egress systems.

Mechanical and Metallurgical Analysis of

Structural Steel; Project Leader: Dr. Frank

W. Gayle

Detennine and analyze the mechanical and metallurgical properties

and quality of steel, weldments, and connections from steel recovered from WTC 1, 2, and 7. Investigation of Active Fire Protection

Systems; Project Leader: Dr. David

D. Evans; Dr. William Grosshandler

Investigate the perfonnance of the active fire protection systems in WTC 1, 2, and 7 and their role in fire control, emergency response, and fate of occupants and responders.

Reconstruction of Thermal and Tenability

Enviromnent; Project Leader; Dr. Richard

G. Gann

Reconstruct the time-evolving temperature, thermal environment,

and smoke movement in WTC 1, 2, and 7 for use in evaluating the

structural performance of the buildings and behavior and fate of

occupants and responders.

Structural Fire Response and Collapse

Analysis; Project Leaders: Dr. John

L. Gross and Dr. Therese P. McAllister

Analyze the response of the WTC towers to fires with and without

aircraft damage, the response of WTC 7 in fires, the performance

of composite steel-trussed floor systems, and determine the most

probable structural collapse sequence for WTC 1, 2, and 7. Occupant Behavior, Egress, and Emergency

Communications; Project Leader: Mr. Jason

D. Averill

Analyze the behavior and fate of occupants and responders, both

those who survived and those who did not, and the performance of

the evacuation system.

Emergency Response Technologies and

Guidelines; Project Leader: Mr. J. Randall

Lawson

Document the activities of the emergency responders from the time

of the tenorist attacks on WTC 1 and WTC 2 until the collapse of

WTC 7, including practices followed and technologies used.

XIV NISTNCSTAR 1-3B, WTC Investigation
Preface

WTC Investigation Projects

structural Collapse

Figure P-1. The eight projects in the federal building and fire safety

investigation of the WTC disaster.

National Construction Safety Team Advisory Committee

The NIST Director also established an advisory committee as mandated under the National Construction

Safety Team Act. The initial members of the committee were appointed following a public solicitation. These were:

• Paul Fitzgerald, Executive Vice President (retired) FM Global, National Construction Safety

Team Advisory Committee Chair

• John Barsom, President, Barsom Consulting, Ltd.

• John Bryan, Professor Emeritus, University of Maryland

• David Collins, President, The Preview Group, Inc.

• Glenn Corbett, Professor, John Jay College of Criminal Justice

• Philip DiNenno, President, Hughes Associates, Inc.

NISTNCSTAR 1-3B, WTC Investigation XV
Preface

• Robert Hanson, Professor Emeritus, University of Michigan

• Charles Thornton, Co-Chairman and Managing Principal, The Thomton-Tomasetti Group,

Inc.

• Kathleen Tiemey, Director, Natural Hazards Research and Applications Information Center,

University of Colorado at Boulder

• Forman Williams, Director, Center for Energy Research, University of California at San

Diego

This National Construction Safety Team Advisory Committee provided technical advice during the

Investigation and commentary on drafts of the Investigation reports prior to their public release. NIST

has benefited from the work of many people in the preparation of these reports, including the National

Construction Safety Team Advisory Committee. The content of the reports and recoinmendations,

however, are solely the responsibility of NIST.

Public Outreach

During the course of this Investigation, NIST held public briefings and meetings (listed in Table P-2) to

solicit input from the public, present preliminary findings, and obtain comments on the direction and

progress of the Investigation from the public and the Advisory Committee.

NIST maintained a publicly accessible Web site during this Investigation at http://wtc.nist.gov. The site contained extensive information on the background and progress of the Investigation.

NIST's WTC Public-Private Response Plan

The collapse of the WTC buildings has led to broad reexamination of how tall buildings are designed,

constructed, maintained, and used, especially with regard to major events such as fires, natural disasters,

and terrorist attacks. Reflecting the enhanced interest in effecting necessary change, NIST, with support

from Congress and the Administration, has put in place a program, the goal of which is to develop and

implement the standards, technology, and practices needed for cost-effective improvements to the safety

and security of buildings and building occupants, including evacuation, emergency response procedures,

and threat mitigation.

The strategy to meet this goal is a three-part NIST-led public-private response program that includes:

• A federal building and fire safety investigation to study the most probable factors that contributed to post-aircraft impact collapse of the WTC towers and the 47-story WTC 7

building, and the associated evacuation and emergency response experience.

• A research and development (R&D) program to (a) facilitate the implementation of

recommendations resulting from the WTC Investigation, and (b) provide the technical basis

for cost-effective improvements to national building and fire codes, standards, and practices

that enhance the safety of buildings, their occupants, and emergency responders.

XVI NISTNCSTAR 1-3B, WTC Investigation
Preface

Table P-2. Public meetings and briefings of the WTC Investigation.

Date Location Principal Af^enda

June 24. 2002 New York City, NY Public meeting: Public comments on the Drajl Plan lor tlic pending WTC Investigation.

August 21, 2002 Gaithersburg, MD Media briefing announcing the formal start of the Investigation.

December 9, 2002 Washington, DC Media briefing on release of the Public Update and NIST request

for photographs and videos. April 8. 2003 New York City, NY Joint public forum with Columbia University on first-person interviews. April 29-30, 2003 Gaithersburg, MD NCST Advisory Committee meeting on plan for and progress on WTC Investigation with a public comment session. May 7, 2003 New York City, NY Media briefing on release of May 2003 Proo^vess Report.

August 26-27, 2003 Gaithersburg, MD NCST Advisory Committee meeting on status of the WTC

investigation with a public comment session. September 17, 2003 New York City, NY Media and public briefing on initiation of first-person data

collection projects.

December 2-3, 2003 Gaithersburg, MD NCST Advisory Committee meeting on status and initial results and release of the Public Update with a public comment session. February 12, 2004 New York City, NY Public meeting on progress and preliminary findings with public

comments on issues to be considered in formulating final recommendations.

June 18,2004 New York City, NY Media/public briefing on release of June 2004 Progress Report. June 22-23, 2004 Gaithersburg, MD NCST Advisory Committee meeting on the status of and

preliminary findings from the WTC Investigation with a public

comment session. August 24, 2004 Northbrook, IL Public viewing of standard fire resistance test of WTC floor system at Underwriters Laboratories, Inc. October 19-20, 2004 Gaithersburg, MD NCST Advisory Committee meeting on status and near complete

set of preliminary findings with a public comment session. November 22, 2004 Gaithersburg, MD NCST Advisory Committee discussion on draft annual report to Congress, a public comment session, and a closed session to discuss pre-draft recommendations for WTC Investigation.

April 5, 2005 New York City, NY Media and public briefing on release of the probable collapse sequence for the WTC towers and draft reports for the projects on

codes and practices, evacuation, and emergency response. June 23, 2005 New York City, NY Media and public briefing on release of all draft reports for the WTC towers and draft recommendations for public comment.

September 12-13.

2005

Gaithersburg, MD NCST Advisory Committee meeting on disposition of public

comments and update to draft reports for the WTC towers. September 13-15,

2005

Gaithersburg, MD WTC Technical Conference for stakeholders and technical community for dissemination of findings and recommendations

and opportunity for public to make technical comments.

• A dissemination and technical assistance program (DTAP) to (a) engage leaders of the

construction and building community in ensuring timely adoption and widespread use of

proposed changes to practices, standards, and codes resulting from the WTC Investigation

and the R&D program, and (b) provide practical guidance and tools to better prepare facility owners, contractors, architects, engineers, emergency responders, and regulatory authorities

to respond to future disasters. The desired outcomes are to make buildings, occupants, and first responders safer in future disaster

events.

NISTNCSTAR 1-3B, WTC Investigation XVll
Preface

National Construction Safety Team Reports on the WTC Investigation

A final report on the collapse of the WTC towers is being issued as NIST NCSTAR 1. A companion

report on the collapse of WTC 7 is being issued as NIST NCSTAR lA. The present report is one of a set that provides more detailed documentation of the Investigation findings and the means by which these

technical results were achieved. As such, it is part of the archival record of this Investigation. The titles of the full set of Investigation publications are:

NIST (National Institute of Standards and Technology). 2005. Federal Building and Fire Safety

Investigation ofthe World Trade Center Disaster: Final Report on the Collapse ofthe World Trade

Center Towers. NIST NCSTAR 1. Gaithersburg, MD, September.

NIST (National Institute of Standards and Technology). 2006. Federal Building and Fire Safety

Investigation ofthe World Trade Center Disaster: Final Report on the Collapse of World Trade Center 7. NIST NCSTAR 1 A. Gaithersburg, MD.

Lew, H. S., R. W. Bukowski, and N. J. Carino. 2005. Federal Building and Fire Safety Investigation of

the World Trade Center Disaster: Design, Construction, and Maintenance ofStructural and Life Safety

Systems. NIST NCSTAR 1-1. National Institute of Standards and Technology. Gaithersburg, MD,

September.

Fanella, D. A., A. T. Derecho, and S. K. Ghosh. 2005. Federal Building and Fire Safety

Investigation of the World Trade Center Disaster: Design and Construction ofStructural Systems.

NIST NCSTAR 1-1 A. National Institute of Standards and Technology. Gaithersburg, MD,

September.

Ghosh, S. K., and X. Liang. 2005. Federal Building and Fire Safety Investigation ofthe World

Trade Center Disaster: Comparison ofBuilding Code Structural Requirements. NIST

NCSTAR 1-lB. National Institute of Standards and Technology. Gaithersburg, MD, September.

Fanella, D. A., A. T. Derecho, and S. K. Ghosh. 2005. Federal Building and Fire Safety

Investigation of the World Trade Center Disaster: Maintenance and Modifications to Structural

Systems. NIST NCSTAR 1-lC. National Institute of Standards and Technology. Gaithersburg,

MD, September.

Grill, R. A., and D. A. Johnson. 2005. Federal Building and Fire Safety Investigation ofthe World

Trade Center Disaster: Fire Protection and Life Safety Provisions Applied to the Design and

Construction of World Trade Center I, 2, and 7 and Post-Construction Provisions Applied after

Occupancy. NIST NCSTAR 1-lD. National Institute of Standards and Technology. Gaithersburg,

MD, September.

Razza, J. C, and R. A. Grill. 2005. Federal Building and Fire Safety Investigation ofthe World

Trade Center Disaster: Comparison of Codes, Standards, and Practices in Use at the Time ofthe

Design and Construction of World Trade Center I, 2, and 7. NIST NCSTAR 1-lE. National

Institute of Standards and Technology. Gaithersburg, MD, September.

Grill, R. A., D. A. Johnson, and D. A. Fanella. 2005. Federal Building and Fire Safety

Investigation ofthe World Trade Center Disaster: Comparison of the 1968 and Current (2003) New

xvni NIST NCSTAR 1-3B, WTC Investigation
Preface

York City Building Code Provisions. NIST NCSTAR 1-lF. National Institute of Standards and

Technology. Gaithersburg, MD, September.

Grill, R. A., and D. A. Johnson. 2005. Federal Building and Fire Safety Investigation of the World

Trade Center Disaster: Amendments to the Fire Protection and Life Safety Provisions of the New

York City Building Code by Local Laws Adopted While World Trade Center 1, 2, and 7 Were in Use. NIST NCSTAR 1-lG. National Institute of Standards and Technology. Gaithersburg, MD,

September.

Grill, R. A., and D. A. Johnson. 2005. Federal Building and Fire Safely Investigation ofthe World

Trade Center Disaster: Post-Construction Modifications to Fire Protection and Life Safety Systems

of World Trade Center 1 and 2. NIST NCSTAR 1-lH. National Institute of Standards and

Technology. Gaithersburg, MD, September.

Grill, R. A., D. A. Johnson, and D. A. Fanella. 2005. Federal Building and Fire Safety Investigation

ofthe World Trade Center Disaster: Post-Construction Modifications to Fire Protection, Life

Safety, and Structural Systems of World Trade Center 7. NIST NCSTAR l-II. National Institute of

Standards and Technology. Gaithersburg, MD, September.

Grill, R. A., and D. A. Johnson. 2005. Federal Building and Fire Safety Investigation ofthe World

Trade Center Disaster: Design, Installation, and Operation ofFuel System for Emergency Power in World Trade Center 7. NIST NCSTAR 1-1 J. National Institute of Standards and Technology.

Gaithersburg, MD, September.

Sadek, F. 2005. Federal Building and Fire Safety Investigation ofthe World Trade Center Disaster:

Baseline Structural Performance and Aircraft Impact Damage Analysis ofthe World Trade Center

Towers. NIST NCSTAR 1-2. National Institute of Standards and Technology. Gaithersburg, MD,

September.

Faschan, W. J., and R. B. Garlock. 2005. Federal Building and Fire Safety Investigation ofthe

World Trade Center Disaster: Reference Structural Models and Baseline Performance Analysis of

the World Trade Center Towers. NIST NCSTAR 1-2A. National Institute of Standards and

Technology. Gaithersburg, MD, September.

Kirkpatrick, S. W., R. T. Bocchieri, F. Sadek, R. A. MacNeill, S. Holmes, B. D. Peterson, R. W. Cilke, C. Navarro. 2005. Federal Building and Fire Safety Investigation ofthe World Trade

Center Disaster: Analysis ofAircraft Impacts into the World Trade Center Towers, NIST

NCSTAR I-2B. National Institute of Standards and Technology. Gaithersburg, MD, September.

Gayle, F. W., R. J. Fields, W. E. Luecke, S. W. Banovic, T. Foecke, C. N. McCowan. T. A. Siewert, and

J. D. McColskey. 2005. Federal Building and Fire Safety Investigation ofthe World Trade Center

Disaster: Mechanical and Metallurgical Analysis ofStructural Steel. NIST NCSTAR 1 -3 . National

Institute of Standards and Technology. Gaithersburg, MD, September.

Luecke, W. E., T. A. Siewert, and F. W. Gayle. 2005. Federal Building and Fire Safety

Investigation ofthe World Trade Center Disaster: Contemporaneous Structural Steel

Specifications. NIST Special Publication 1-3 A. National Institute of Standards and Technology.

Gaithersburg, MD, September.

NIST NCSTAR 1-3B, WTC Investigation xix
Preface

Banovic, S. W. 2005. Federal Building and Fire Safety Investigation ofthe World Trade Center

Disaster: Steel Inventoiy and Identification. NIST NCSTAR 1 -3B. National Institute of Standards

and Technology. Gaithersburg, MD, September.

Banovic, S. W., and T. Foecke. 2005. Federal Building and Fire Safety Investigation of the World

Trade Center Disaster: Damage and Failure Modes ofStructural Steel Components. NIST

NCSTAR 1-3C. National Institute of Standards and Technology. Gaithersburg, MD, September.

Luecke, W. E., J. D. McColskey, C. N. McCowan, S. W. Banovic, R. J. Fields, T. Foecke,

T. A. Siewert, and F. W. Gayle. 2005. Federal Building and Fire Safety Investigation ofthe World

Trade Center Disaster: Mechanical Properties ofStructural Steels. NIST NCSTAR 1-3D.

National Institute of Standards and Technology. Gaithersburg, MD, September.

Banovic, S. W., C. N. McCowan, and W. E. Luecke. 2005. Federal Building and Fire Safety

Investigation ofthe World Trade Center Disaster: Physical Properties ofStructural Steels. NIST

NCSTAR 1-3E. National Institute of Standards and Technology. Gaithersburg, MD, September.

Evans, D. D., R. D. Peacock, E. D. Kuligowski, W. S. Dols, and W. L. Grosshandler. 2005. Federal

Building and Fire Safety Investigation ofthe World Trade Center Disaster: Active Fire Protection

Systems. NIST NCSTAR 1-4. National Institute of Standards and Technology. Gaithersburg, MD,

September.

Kuligowski, E. D., D. D. Evans, and R. D. Peacock. 2005. Federal Building and Fire Safety

Investigation ofthe World Trade Center Disaster: Post-Construction Fires Prior to September II, 2001. NIST NCSTAR 1-4A. National Institute of Standards and Technology. Gaithersburg, MD,

September.

Hopkins, M., J. Schoenrock, and E. Budnick. 2005. Federal Building and Fire Safety Investigation

ofthe World Trade Center Disaster: Fire Suppression Systems. NIST NCSTAR 1-4B. National

Institute of Standards and Technology. Gaithersburg, MD, September.

Keough, R. J., and R. A. Grill. 2005. Federal Building and Fire Safety Investigation ofthe World

Trade Center Disaster: Fire Alarm Systems. NIST NCSTAR 1-4C. National Institute of Standards

and Technology. Gaithersburg, MD, September.

Ferreira, M. J., and S. M. Strege. 2005. Federal Building and Fire Safety Investigation ofthe

World Trade Center Disaster: Smoke Management Systems. NIST NCSTAR 1-4D. National

Institute of Standards and Technology. Gaithersburg, MD, September.

Gann, R. G., A. Hamins, K. B. McGrattan, G. W. Mulholland, H. E. Nelson, T. J. Ohlemiller,

W. M. Pitts, and K. R. Prasad. 2005. Federal Building and Fire Safety Investigation ofthe World Trade

Center Disaster: Reconstruction ofthe Fires in the World Trade Center Towers. NIST NCSTAR 1-5. National Institute of Standards and Technology. Gaithersburg, MD, September.

Pitts, W. M., K. M. Butler, and V. Junker. 2005. Federal Building and Fire Safety Investigation of

the World Trade Center Disaster: Visual Evidence, Damage Estimates, and Timeline Analysis.

NIST NCSTAR 1-5 A. National Institute of Standards and Technology. Gaithersburg, MD,

September.

XX NIST NCSTAR 1-3B, WTC Investigation
Preface

Hamins, A., A. Maranghides, K. B. McGrattan, E. Johnsson, T. J. Ohlcmillcr, M. Donnelly,

J. Yang, G. Mulholland, K. R. Prasad, S. Kukuck, R. Anlcitner and T. McAllister. 2005. Federal

Building and Fire Safety Investigation ofthe World Trade Center Disaster: Experiments and

Modeling ofStructural Steel Elements Exposed to Fire. NIST NCSTAR 1 -5B. National Insii lute ol Standards and Technology. Gaithersburg, MD, September.

Ohlemiller, T. J., G. W. Mulholland, A. Maranghides, J. J. Filliben, and R. G. Gann. 2005. Federal

Building and Fire Safety Investigation ofthe World Trade Center Disaster: Fire Tests ofSingle

Office Workstations. NIST NCSTAR 1-5C. National Institute of Standards and Technology.

Gaithersburg, MD, September.

Gann, R. G., M. A. Riley, J. M. Repp, A. S. Whittaker, A. M. Reinhom, and P. A. Hough. 2005.

Federal Building and Fire Safety Investigation ofthe World Trade Center Disaster: Reaction of

Ceiling Tile Systems to Shocks. NIST NCSTAR 1-5D. National Institute of Standards and

Technology. Gaithersburg, MD, September.

Hamins, A., A. Maranghides, K. B. McGrattan, T. J. Ohlemiller, and R. Anleitner. 2005. Federal

Building and Fire Safety Investigation ofthe World Trade Center Disaster: Experiments and

Modeling ofMultiple Workstations Burning in a Compartment. NIST NCSTAR 1-5E. National

Institute of Standards and Technology. Gaithersburg, MD, September.

McGrattan, K. B., C. Bouldin, and G. Forney. 2005. Federal Building and Fire Safety

Investigation ofthe World Trade Center Disaster: Computer Simulation ofthe Fires in the World

Trade Center Towers. NIST NCSTAR 1-5F. National Institute of Standards and Technology.

Gaithersburg, MD, September.

Prasad, K. R., and H. R. Baum. 2005. Federal Building and Fire Safety Investigation ofthe World

Trade Center Disaster: Fire Structure Interface and Thermal Response ofthe World Trade Center

Towers. NIST NCSTAR 1-5G. National Institute of Standards and Technology. Gaithersburg,

MD, September.

Gross, J. L., and T. McAllister. 2005. Federal Building and Fire Safety Investigation ofthe World Trade

Center Disaster: Structural Fire Response and Probable Collapse Sequence ofthe World Trade Center

Towers. NIST NCSTAR 1-6. National Institute of Standards and Technology. Gaithersburg, MD,

September.

Carino, N. J., M. A. Stames, J. L. Gross, J. C. Yang, S. Kukuck, K. R. Prasad, and R. W. Bukowski.

2005. Federal Building and Fire Safety Investigation ofthe World Trade Center Disaster: Passive

Fire Protection. NIST NCSTAR 1-6A. National Institute of Standards and Technology.

Gaithersburg, MD, September.

Gross, J., F. Hervey, M. Izydorek, J. Mammoser, and J. Treadway. 2005. Federal Building and

Fire Safety Investigation ofthe World Trade Center Disaster: Fire Resistance Tests ofFloor Truss

Systems. NIST NCSTAR 1-6B. National Institute of Standards and Technology. Gaithersburg,

MD, September.

Zarghamee, M. S., S. Bolourchi, D. W. Eggers, O. O. Erbay, F. W. Kan, Y. Kitane, A. A. Liepins,

M. Mudlock, W. I. Naguib, R. P. Ojdrovic, A. T. Sarawit, P. R Barrett, J. L. Gross, and

NIST NCSTAR 1-3B, WTC Investigation
Preface

T. P. McAllister. 2005. Federal Building and Fire Safety Investigation ofthe World Trade Center

Disaster: Component, Connection, and Subsystem Structural Analysis. NIST NCSTAR 1-6C.

National Institute of Standards and Technology. Gaithersburg, MD, September.

Zarghamee, M. S., Y. Kitane, O. O. Erbay, T. P. McAllister, and J. L. Gross. 2005. Federal

Building and Fire Safety Investigation ofthe World Trade Center Disaster: Global Structural

Analysis ofthe Response ofthe World Trade Center Towers to Impact Damage and Fire. NIST

NCSTAR 1-6D. National Institute of Standards and Technology. Gaithersburg, MD, September.

McAllister, T., R. W. Bukowski, R. G. Gann, J. L. Gross, K. B. McGrattan, H. E. Nelson, L. Phan,

W. M. Pitts, K. R. Prasad, F. Sadek. 2006. Federal Building and Fire Safety Investigation ofthe World

Trade Center Disaster: Structural Fire Response and Probable Collapse Sequence of World Trade

Center?. (Provisional). NIST NCSTAR 1-6E. National Institute of Standards and Technology.

Gaithersburg, MD.

Gilsanz, R., V. Arbitrio, C. Anders, D. Chlebus, K. Ezzeldin, W. Guo, P. Moloney, A. Montalva,

J. Oh, K. Rubenacker. 2006. Federal Building and Fire Safety Investigation ofthe World Trade

Center Disaster: Structural Analysis ofthe Response of World Trade Center 7 to Debris Damage

and Fire. (Provisional). NIST NCSTAR 1-6F. National Institute of Standards and Technology.

Gaithersburg, MD.

Kim, W. 2006. Federal Building and Fire Safety^ Investigation ofthe World Trade Center

Disaster: Analysis ofSeptember 11, 2001, Seismogram Data. (Provisional). NIST NCSTAR 1-6G.

National Institute of Standards and Technology. Gaithersburg, MD.

Nelson, K. 2006. Federal Building and Fire Safety Investigation ofthe World Trade Center

Disaster: The Con Ed Substation in World Trade Center 7. (Provisional). NIST NCSTAR 1-6H.

National Institute of Standards and Technology. Gaithersburg, MD.

Averill, J. D., D. S. Mileti, R. D. Peacock, E. D. Kuligowski, N. Groner, G. Proulx, P. A. Reneke, and

H. E. Nelson. 2005. Federal Building and Fire Safety Investigation of the World Trade Center Disaster:

Occupant Behavior, Egress, and Emergency Communication. NIST NCSTAR 1-7. National Institute of

Standards and Technology. Gaithersburg, MD, September.

Fahy, R., and G. Proulx. 2005. Federal Building and Fire Safety Investigation ofthe World Trade

Center Disaster: Analysis ofPublished Accounts ofthe World Trade Center Evacuation. NIST

NCSTAR 1-7A. National Institute of Standards and Technology. Gaithersburg, MD, September.

Zmud, J. 2005. Federal Building and Fire Safety Investigation ofthe World Trade Center . Disaster: Technical Documentation for Sw\>ey Administration. NIST NCSTAR 1-7B. National

Institute of Standards and Technology. Gaithersburg, MD, September.

Lawson, J. R., and R. L. Vettori. 2005. Federal Building and Fire Safety Investigation ofthe World

Trade Center Disaster: The Emergency Response Operations. NIST NCSTAR 1-8. National Institute of

Standards and Technology. Gaithersburg, MD, September.

xxn NIST NCSTAR 1-3B, WTC Investigation
Acknowledgments

National Institute of Standards and Technology (NIST) thanks these volunteers of the Structural

Engineers Association of New York for their efforts in the recovery of the steel components: Amit

Bandyopadhyay, Anamaria Bonilla, Peter Chipchase, Anthony Chuliver, Edward DePaola,

Louis Errichiello, James Fahey, Ramon Gilsanz, Jeffrey Hartman, David Hoy, Dean Koutsoubis, Andrew

McConnell, Rajani Nair, Alan Rosa, David Sharp, Gary Steficek, and Kevin Terry. Countless hours were

unselfishly spent in the recovery yards searching for these invaluable pieces that are an integral

component of this investigation. Further, the following people are recognized for their outstanding

leadership roles throughout the recovery effort: Ramon Gilsanz, primary leader of the recovery effort; David Sharp, coordinator of volunteer activities and author of the guide used for the selection of suitable

pieces; and Audrey Massa of Federal Emergency Management Agency (FEMA), leader for documentation and cataloguing of efforts and pieces to be saved.

The FEMA/American Society of Civil Engineers Building Performance Assessment Team;

Professor A. Astaneh-Asl of the University of California, Berkeley, California; and the National Science

Foundation are also acknowledged for their help in the recovery effort.

Blanford Land Development Corporation; Hugo Neu Schnitzer, Inc.; and Metal Management, Inc. are thanked for the initial storing of the structural steel during the clean-up effort of the World Trade Center

site and for their assistance and patience during the review, abatement, and final removal of pieces of

interest to the investigation.

NIST also thanks the Port Authority of New York and New Jersey for its assistance in surveying,

sectioning, and transporting the technically significant structural steel collected by the Port Authority and

stored at John F. Kennedy International Airport.

NISTNCSTAR 7-36, WTC Investigation xxin
Acknowledgments

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xxiv NIST NCSTAR 1-3B, WTC Investigation
Executive Summary

As a result of the recovery efforts of the Structural Engineers Association of New York, Federal

Emergency Management Agency/American Society of Civil Engineers, and the National Institute of

Standards and Technology (NIST), NIST possesses 236 structural steel elements from the World Trade

Center (WTC) buildings. These pieces represent a small fraction of the enormous amount of steel examined at the various recovery yards where the debris was sent as the WTC site was cleared. Elements

located in or near the impact zone and fire damaged regions were emphasized in the selection process. These samples include full exterior column panels, core columns, portions of the floor truss members,

channels used to attach the floor trusses to the interior columns, and other smaller structural components

(e.g., bolts, diagonal bracing straps, aluminum facade, etc.). These structural components were used for evaluation and/or testing relative to the fire and structural response of the WTC buildmgs.

Upon arrival at NIST, the samples were catalogued, documented, and when possible, identified as to their

precise, as-built location within the buildings. The vast majority of the structural components are from

WTC 1 and WTC 2. It is estimated that roughly 0.25 percent to 0.5 percent of the 200,000 tons of steel used in the construction of the two towers was recovered. The following lists the recovered structural

steel elements:

• Out of the 90 exterior panels recovered, the as-built location of 42 distinct sections was

unambiguously identified within WTC 1 and WTC 2:

- 26 panels from WTC 1 : 22 from or near the impact floors, 4 hit directly by the airplane,

- 1 6 panels from WTC 2: 4 near the impact floors.

• Out of the 55 wide flange sections and built-up box sections recovered, 12 core columns were

positively identified from WTC 1 and WTC 2, including:

- Two columns from the fire floors of WTC 1

,

- Two columns from the impact zone of WTC 2.

• 23 pieces of floor truss material from WTC 1 and WTC 2 were recovered; however, the asbuilt location of the trusses within the buildings could not be identified.

• 25 pieces of channel material that connected the floor trusses to the core columns in WTC 1 and WTC 2 were recovered; however, the as-built location of the channels within the

buildings could not be identified.

• One piece of floor framing from outside the core of the 1 07th floor of WTC 1

.

• Seven coupons from WTC 5 were removed in the field and sent to NIST.

• No pieces could be unambiguously identified as being from WTC 7.

NISTNCSTAR 1-3B, WTC Investigation XXV
Executive Summary

The design drawings for WTC 1 and WTC 2 designate 14 different grades (or strengths) of steel for the

exterior panels, four different grades for the core columns, and two grades for the floor trusses. From the

recovered and identified columns, whether perimeter or core, a one to one correlation was observed

between the minimum yield strength specified by the design drawings and the observed stampings and/or

stencilings on the samples, with the exception of the 85 ksi and 90 ksi material that was substituted with

100 ksi plate. The recovered structural elements yielded sufficient representative samples for the

following: ,

• All 1 2 grades of exterior panel material,

• Two grades of the core column material (representing 99 percent, by total number, of the

columns),

• Both grades for the floor truss material.

This collection of steel from the WTC towers is sufficient for determining the quality of the steel and for detemiining mechanical properties as input to models of building performance. The lack of WTC 7 steel precludes tests on actual material from the structure; however, WTC 7 was constructed of three grades of

conventional steel (36 ksi, 42 ksi, and 50 ksi), and literature values may be used to estimate properties.

XXVI NISTNCSTAR 1-3B, WTC Investigation
Chapter 1 Introduction

1 .1 PURPOSE OF REPORT

The purpose of analyzing structural steel available from World Trade Center (WTC) 1, 2, and 7 is to detemiine the metallurgical and mechanical properties and quality of the metal, weldments, and

connections and to provide these data for other analyses in the National Institute of Standards and

Technology (NIST) Investigation. The properties determined were used in two ways:

• Properties were correlated with the design requirements of the buildings to determine if the

specified steel was in place in the towers.

• Properties were supplied as input for models of building performance.

1.2 SCOPE OF REPORT

The scope of this report covers the inventory and identification of steels recovered from the WTC

buildings. Approximately 236 pieces of WTC steel were available for study at NIST. These pieces

represent a small fraction of the steel examined at the various recovery yards where the steel was sent as the WTC site was cleared.

For reference throughout this report, NIST NCSTAR 1-3A' describes the tower structure and critical

structural elements discussed below. This includes the structural design and properties specified by the

structural engineers for columns, floor systems, and connections. Further, NIST NCSTAR 1-3 A also

discusses the contemporaneous (late 1960s era) specifications for various types and grades of steel designated by ASTM International, the American Institute of Steel Construction (AISC), and other

national and international organizations. It also includes information from numerous suppliers of the steel

for the structure.

This reference is to one of the companion documents from this Investigation. A list of these documents appears in the Preface

to this report.

NIST NCSTAR 1-3B, WTC Investigation 1
Chapter 1

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2 NISTNCSTAR 1-3B, WTC Investigation
Chapter 2

Background Information Related to Recovery of WTC

Structural Steel

Beginning in October 2001, members of the Federal Emergency Management Agency (FEMA),

American Society of Civil Engineers (ASCE), Building Performance Study (BPS) Team, members of the

Structural Engineers Association of New York (SEAoNY), and Professor A. Astaneh-Asl of the

University of California, Berkeley, California (Astaneh-Asl 2002), with support from the National

Science Foundation, began work to identify and collect World Trade Center (WTC) structural steel from

the various recovery yards where debris, including the steel, was taken during the cleanup effort. Dr. J. Gross, a structural engineer at the National Institute of Standards and Technology (NIST) and a member of the FEMA/ASCE BPS Team, was involved in these early efforts.

There were four major sites where debris from the WTC buildings was shipped during the clean-up effort

in which the volunteers worked. These were:

• Hugo Neu Schnitzer, Inc., Fresh Kills Landfill in Staten Island, New Jersey;

• Hugo Neu Schnitzer East, Inc., Claremont Terminal in Jersey City, New Jersey;

• Metal Management, Inc., in Newark, New Jersey; and

• Blanford and Co. in Keasbey, New Jersey.

The volunteers searched through unsorted piles of steel and other debris for pieces from the WTC

buildings, specifically searching for (McAllister 2002):

• Exterior column panels and interior core columns from WTC 1 and WTC 2 that were exposed

to fire and/or impacted by the aircraft;

• Exterior column panels and interior core columns from WTC 1 and WTC 2 directly above

and below the impact zones;

• Badly burned pieces from WTC 7;

• Connections from WTC 1, 2, and 7 (e.g., seat connections, single-shear plates, and column

splices);

• Bolts in all conditions;

• Floor trusses, including stiffeners, seats, and other components; and

• Any pieces that in the engineers' professional opinion might be useful.

NISTNCSTAR 1-3B, WTC Investigation 3
Chapter 2

Once identified for recovery, the samples were marked as "SAVE" and given an alphanumeric code

relative to the recovery yard from which they came and an accession number. Some pieces were not saved in their entirety, but instead, small portions were removed, hereafter called coupons. (Coupons

were also removed in the field for WTC 5, held at Gilsanz Murray Steficek, LLP [GMS, LLP], and later brought to NIST.)

Facing concern that the identified steel may not be properly preserved in the recovery yards, NIST

arranged for the steel to be shipped to its campus in Gaithersburg, Maryland, starting in March 2002.

Professor Astaneh-Asl also granted NIST pennission to take custody of the steel that he had personally

marked. Before the samples were shipped to the NIST campus, environmental testing for asbestos and

analysis of the paint for lead was conducted. Volunteers from SEAoNY, with assistance from additional

NIST personnel, continued their presence at the recovery yards and identified, catalogued, and shipped

steel specimens to NIST through October 2002. The structural components recovered now constitute the

material base from which samples are being removed for further evaluation and or testing relative to the

fire and structural response of the WTC buildings as part of the WTC Investigation.

Structural steel elements were also collected and held by the Port Authority of New York and New Jersey

(PANYNJ) in Hanger 17 located at John F. Kennedy (JFK) International Airport. The main goal of the

PANYNJ project was to decontaminate and preserve the steel, as well as other WTC artifacts, for future

exhibits and memorials. A complete listing of the pieces held by PANYNJ can be found in the

Presen'ation and Inventory Report prepared by Voorsanger and Associates Architects, PC." NIST

personnel visited the hanger and identified 12 additional pieces that were considered important to its Investigation. Six of these samples were moved whole to the Gaithersburg campus. The remaining

pieces had portions removed and sent to NIST, with the bulk of the structural element remaining at JFK International Airport.

' Voorsanger and Associates Architects. PC. 2002. ^TC Archives Interim Storage Facility: JFK International Airport: Preservation and Inventory Report, Draft 2. New York, NY, November.

4 NISTNCSTAR 1-3B, WTC Investigation
Chapter 3

Structural Elements Recovered from the WTC Buildings

3.1 present location and labeling of structural steel

elements

At present, the National Institute of Standards and Technology (NIST) possesses 236 labeled samples

from the World Trade Center (WTC) buildings. While the majority of the NIST-held samples reside on

the Gaithersburg campus, some samples were shipped to the Boulder, Colorado, campus for mechanical

property testing following initial documentation.

As samples were delivered, overall images of the pieces were taken for record-keeping purposes. An

example is shown in Fig. 3-1. Samples are identified by their original alphanumeric identification codes

assigned by Structural Engineers Association of New York to be consistent with the Federal Emergency

Management Agency report. However, there were cases in which two different codes were found on one

piece. In these instances, if the pieces were already undergoing documentation procedures, the first code

noted was used. Samples that arrived lacking a code were labeled as part of the U series. Additionally,

samples brought from Hanger 17 at Jolin F. Kennedy International Airport maintained their "B"-series

labels provided in the Voorsanger report.^

Appendix A, Table A-1, is a complete list of each sample received, in alphanumeric order, with its

classification, a brief description of the component, and the location of the piece on the NIST campus.

These samples range from full exterior column panels to pieces of bolts and bags of glass and other debris

fragments. The pieces were classified into one of eight categories:

Classification No. of Pieces Symbol

Exterior column panel sections (flat wall or comer) 94 C, CC, or Cn

Bowtie pieces 2 BT

Rectangular built-up box column (not perimeter column) 11 RB

Wide flange sections 44 W

Floor trusses 23 J Channels 25 Ch

Coupons from WTC 5 7 Cn5

Miscellaneous (isolated bolts, floor hanger components, or other) 30 B.H.O

Tables A-2 through A-1 1 list the pieces separated by type, and Figs. A-1 through A- 14 displays

characteristic photographs of the various pieces.

NISTNCSTAR 1-3B, WTC Investigation 5
Chapter 3

E

Source: Nistf

Figure 3-1. Characteristic "overall" view of the

samples taken for each piece received.

Sample shown here is C-14.

6 NISTNCSTAR 1-3B, WTC Investigation
structural Elements Recovered from the WTC Buildings

3.2 IDENTIFICATION OF WTC STRUCTURAL STEEL ELEMENTS

Information from Leslie E. Robertson Associates (LERA) indicates that all structural steel pieces in WTC

1 and WTC 2 were uniquely identified by stampings (recessed letters and numbers) and/or painted

stencils."^ NIST has been successflil in finding these identification markings on many of the perimeter

panel sections, core columns, and other wide flange members. Of the 94 pieces of perimeter panel

labeled in Table A-1, 90 distinct panels were observed. (The other four pieces of perimeter column had

become separated from the main panel during salvage and were subsequently labeled C-13a, C-16a, C28b, and K-16a.) At this time, of the 90 panels, 42 distinct exterior column panels have been identified

and 1 partially identified. Tables 3-1 and 3-2 list these samples, respectively, with Fig. 3-2 showing the

relative locations of the identified exterior panels within the top third of the buildings. Significantly more

pieces were recovered from WTC 1 than WTC 2. Table 3-3 lists the 12 core columns in NIST's

possession that have been positively identified through their stampings. An additional sample, C-83, is also listed in this group. Though no markings were found on the piece, the shape and dimension of this sample are in conformance with the design drawings for core columns and it has a similar appearance to core column C-90. Additionally, there are 13 pieces of wide flange sections that have stampings and/or

markings with a different code. Table 3-4. After review of these stampings by staff members from both

the Port Authority of New York and New Jersey (PANYNJ) and LERA, no definite correlation between

the markings and the contract document member labels was found. It was the opinion of LERA that the

stampings/marks are shop marks that may or may not have been indicated in the original shop drawings.

LERA beheves that it does not have within its possession any shop drawings that are consistent with the members shown. Further, LERA studied the images to determine if the box members could be grouped

into a member type typically found in the WTC buildings and was unsuccessful. Therefore, the as-built

location of these pieces could not be determined nor could it be confirmed that they were part of the

structural steel from the WTC towers.

The positive identification of the structural elements was made possible by deciphering the stampings

and/or stencils found on them. During the fabrication process, the exterior panel sections were stamped at the bottom of the center column on the inside face. These stampings indicated the building, center column line number, and floors spanned by the columns. The core columns had stampings placed at the

lower end of the component near the connector. The building was typically represented as "A" for WTC 1 and "B" for WTC 2. An example of a stamping found on an exterior column is shown in Fig. 3-3, where the stamping indicates that the piece was from WTC 2, with center column line number

206, spanning floors 83 through 86. Core column material was found to have similar markings

(Fig. 3^). Other stampings have also been found on the flanges of the perimeter columns that indicated

the column type (Fig. 3-5 and Table 3-5) as well as the specified minimum yield strength of the column.

All of these stampings typically reside within 1 m from the bottom of the column.

^ Faschan, W. 2002. Leslie E. Robertson Associates. New York. NY, personal communication to F. Gayle. Project Leader,

World Trade Center Investigation, National Institute of Standards and Technology. Gaithersburg, MD, May 21

.

NISTNCSTAR 1-3B, WTC Investigation 7
Chapter 3

Table 3-1. Identified exterior column panel pieces from WTC 1 and WTC 2. NIST

1> a JIlc 1 ype l^CsLI ipilUII 1^1 t\t\ Derrick

ui> isiun

1 lull COIUIIIII WTP W 0 1 V- Z

/in /I M A

B-1024 C Full panel WTC 2 154 21-24 NA

B-1043 c Full panel WTC 2 406 40^3 NA

B-1044 c Full panel WTC 2 409 40^3 NA

C-10 c Full panel WTC 1 451 85-88 5x

C-13 cc

c

Rectangular column with spandrel

rdriidi ui single coiuiun

WTC 2 W 1 »^ z

200

1 J 7

90-92

on Q7

569

joy

C 1 A c 1 cuiumn, lower i/j WTP W 1 1 \_ Z cSj—o / J^7n/u C 1 s c J columns, Doiiom z/j WTP W 9 1 v_ Z ZTinjU M A n 3 columns, lower 1/2 \X/TP W 1 1 C 1

1 ^1 1 J / Q1yj—OAyo AOoy

i^-Z'f 3 columns, upper 1/3 \1/TP W 7 1 C Z ZUJ

7/1 /4—77/ / IN A

V^-Z J c 1 column, lower 1/2 W 1 C 1 7zuoHA oy— SO 07yz AQoy

p /in 2 columns, lower 2/3 \X/TP W 1 1 L. 11 lA 1 jO OS 1 n 1 y o— 1 u 1 AvOX

L-4D L Nearly full panel W 1 L Z

1 ^7 1 J / AC06—/711 ^ AQ joy

L-48 Nearly 2 full columns \\/TP W 7 IL Z

/I /n 44Z Q 1 Q/1 y i—y4 JNA

i_ -J J 1 column, lower 1/3 \X/TP 1 7 no zuv y4—y / M A IN A

P CO 2 full columns \X/TP W 0 1 c z7 1 ^ Z 1 J 17 1

'\ 1 Z— 1 J M A IN A

L-yz L 1 column, lower 1/3 W 1 L Z

1 in 1 iU Q1yj—OAyo XT A IN A

1 column, lower 1/3 XX^TP 1 QQyy— 1 n7 1 uz XT A IN A

pp 2 full columns XX/TP 1 1 7/1

1 Z4 7n 71 /U— / D

XT A IN A

V 1 Jv1

L 3 columns, lower 1/3 XX/TP 1 700 zuy Q7 1 nn y /— luu XT A IN A

IS.-Z L 1 column, lower 2/3 XX/TP 1 7 1

A

Z3d Q7 Q's yz—y J

XT A IN A

iVl-Z v_ Full panel XX/TP W 1 1 L 1

1 "JO OA QQ yo-yy A1 M-lua 3 columns, middle section 1/3 XX/TP W 7 1 L. Z 700 zuy C7oZ—o J

XT A IN A

IVJ- J UD 3 columns, lower 1/2 XX/TP W 7 1 L Z ZUD 81 8A o J—OU ^ AQ joy

M-ZU 2 columns, lower 1/3 XX/TP 1 1 7 1 1 Z 1 QQ 1 07 yy— luz A1

m-zd V_ Full panel XX/TP W 1 1 L 1 1 JU on Qi yu—y J AvOX

IVl-Z / 2 columns, lower % XX/TP W 1 1 V_ 1

1 in Q1 QA y 3—yo A1

iVl-Zo v„ 3 columns, lower % XX/TP ") W 1 Z

1/1 ^ Q8yo- 1 ni lui XT A IN A

2 columns, lower 1/3 XX/TP I 1 11 Q/l y4—Q7y / A^

IN -

1

2 full columns XX/TP 1 7 1 C Z 1 O 87 8*; oZ—o J

XT A IN A

IN - / Full panel XX/TP 1 1 77 1 Z / Q7y /— 1 nn luu XT A IN A

1 N O P F"iili t^^inf*! WTP VV 1 V. 11 97-100 67

N-9 c Nearly full panel WTC 1 154 101-104 69

N-10 c 2 columns, lower 2/3 WTC 1 115 89-92 6x

N-12 c 2 full columns WTC 1 206 92-95 69

N-13 c 3 columns, lower 1/3 WTC 1 130 99-102 63

8 NISTNCSTAR 1-3B, WTC Investigation
structural Elements Recovered from the WTC Buildings

Table 3-1. Identified exterior column panel pieces from WTC 1 and WTC 2 (continued).

NIST

Name Type Description BIdg. Column Floors

Otrrick

Di\ ision N-99 C Nearly full panel WTC 1 14X 99-102 (,1 N-101 C Full panel WTC 1 133 100-103 65

S-1 c 2 columns, lower 1/3 WTC 1 433 79-82 47

S-9 c Full panel WTC 1 133 97-100 NA

S-10 c 2 columns, lower 1/2 WTC 1 224 92-95 NA

S-14 c Full panel WTC 2 218 91-94 557

Key: NA, information not available. Note: "x" in the derrick division column indicates an unreadable number.

Table 3-2. Partially identified exterior column panel from WTC 1 or WTC 2. NIST

Name Type Description BIdg. Column Floors

C-117 C 3 columns, lower 1/3 NA NA 100-104

Key: NA, information not available.

Till /'

105

400 series 300 series 200 series 100 series

WTC 1 West face

WTC 2 South face

WTC 1 South face

WTC 2 East face

WTC 1 East face

WTC 2 North face

WTC 1 North face

WTC 2 West face

Note: WTC 1 panels are shown in green and WTC 2 panels are in blue. Figure 3-2. Location of the exterior panels recovered from the top third of WTC 1 and WTC 2.

NISTNCSTAR 1-3B, WTC Investigation 9
Chapter 3

Table 3-3. Identified pieces of core column material from WTC 1 and WTC 2.

NIST Namp Pnliim \j 1 U III nII r lUUI a

Derrick

ril\'ICI ATI mJi y I5IUII D-R 101 lull1 RR OCaVy 1 CC lclll££,Ul(ll CUlUlllll wxr vv 1 1 1 JS 1

1 —JHS4 J J O U 1 JZ.- 1 RR jmCaVy rpptiin fTi 1 1 1* rr^liifnn ICClall^Uldl dJJUlllll wxr vv 1 1 V. 1 RO^ IS1 J— 11 Ro JS7z. D-U 1 J Z. RR OCaVy 1 LallL;Ulal ClMUlllll vv 1 \_ 1 sod J J—JK) JS 11 J\J

V_ -OD RR jnCaVy 1 CClallLi,Ulal CUlUlIlll N A N A N A N A RR nCaVy JCLlalJ^Uial CUiUlIUl vv 1 ^ Rfll oVj 1 RO R^ sso HZ

\^ oo

u

IVD RR jmCaVy 1 lallL^Uial CUlUllllI WTr vv 1 V- ^9 ROl OU 1 11 RO sso HZ

V, ~y\j IVD RR liCaVy 1 CL lalliI,Ulal LUlUlllll 701 / U

1

19 IS CV_ -J\J ^0 nrUl ^-1 O 1 z. Wvv \a/iH(=* TlQnfT(=» cf^f^tir^n VV JUC ilall^C i>CL llUll WTr T vv 1 ^ ^ 1 OOR 11 04UH—1

1 0^UU IMA In r\ r-65 or S-8 w Widp flatifTP <sPrtinn WTC 1 904 86-89 52 36

C-71 w Wide flange section WTC 1 904 77-80 NA 36

C-80 w Wide flange section WTC 1 603 92-95 51 36

C-155 w Wide flange section WTC 1 904 83-86 52 36

HH or S-2 w Wide flange section WTC 1 605 98-101 53 42

a. C-83 was not positively identified but due to similar size and shape was deemed a core column. Key: NA, information not available.

Table 3-4. Other built-up box columns and wide flange sections from WTC 1 and WTC 2 with ambiguous stampings and/or markings.

NIST Name Type Description Markings

C-79 RB Thin rectangular column 101 A 81-85-87-92 52

C-101 RB Thin rectangular column 78A 10 27 50

C-154 RB Thin rectangular column 825: 107-108 52

C-26 W Three connected wide flange sections 604/605 107 64 50

C-44 W Wide flange section 59 S 563

C-45 W Wide flange section 16 S2 563 F, 50

C-60 W Wide flange section 193 SI 69

C-61 W Wide flange section 150 S 69

C-62 w Wide flange section 224 (S) <48> F,50

M-17 w Wide flange section 163 (9) 62 F, 36

M-23 w Wide flange section F 2010

M-37 w Wide flange section 130 (8x-92) <50>

M-38 w Wide flange section F,42

Note: "x" indicates an unreadable number.

10 NISTNCSTAR 1-3B, WTC Investigation
structural Elements Recovered from the WTC Buildings
Source: NIST. Figure 3-4. Example of stampings placed on one end of a core column.

12 NISTNCSTAR 1-3B, WTC Investigation
structural Elements Recovered from the WTC Buildings

Plate 2

b) =

Figure 3-5. (a) Example of stamping placed on flange indicating the column type (120),

and (b) schematic indicating the various plates corresponding to Table 3-5.

NISTNCSTAR 1-3B, WTC Investigation 13
Chapter 3

Table 3-5. Examples of column types with corresponding

plate gauges.

'

rlalc 1 r laic ^ r 141c J Column Type (in.) (in.) (in.) 120 1/4 1/4 1/4

121 5/16 1/4 1/4 122 3/8 1/4 1/4

123 7/16 1/4 1/4 124 1/2 1/4 1/4

125 9/16 1/4 1/4 126 5/8 1/4 1/4

128 3/4 1/4 1/4 129 13/16 5/16 5/16

133 1 1/16 3/8 3/8

149 2 1/16 1 1/16 1 1/16

150 2 1/8 3/4 3/4

152 2 1/4 3/4 3/4

334 1 1/8 3/8 3/8

335 1 3/16 7/16 7/16

520 1/4 1/4 1/4 522 3/8 1/4 1/4

Each of the structural elements was additionally stenciled in white or yellow lettering with similar

building information. For the exterior panel sections, the stenciling was located on or near the lower

spandrel on the interior face. Figure 3-6 (a) shows a typical stenciling found on a perimeter panel,

indicating this piece was in WTC 2, with center column line number 300, spanning floors 85 through 87. For the core columns, both stenciling and handwritten codes have been observed on the recovered pieces.

Figure 3-6 (b) shows one of these stencilings from a core column located in WTC 1.

Also seen in Fig. 3-6 (a) are two other indicators, 3T and <570>, found on the exterior panel sections.

These markings are the estimated piece tonnage (1 ton equals approximately 907 kg) and the erector's derrick division number, respectively. This information was also stamped on some of the core column

pieces (see Fig. 3-4). The erector, Karl Koch Erecting Co., Inc., assigned derrick divisions 47 through

70 for WTC 1 and derrick divisions 547 through 570 for WTC 2.'' Each division was assigned to a

specific area of the building and shared a crane with other nearby derrick divisions. Therefore, a single crane may have lifted pieces from derrick divisions 65, 67, and 69. Figure 3-7 shows the derrick division

numbers that hoisted the specific columns for both buildings, according to the derrick numbers found on

structural elements with positive identification (also shown in Tables 3-2 and 3-3).

"* PONYA (Port of New York Authority). 1967. Communication to Steel Fabricators, Detailers, and Erectors, Shop drawing

procedures and marking systems. May 1

.

14 NISTNCSTAR 1-3B, WTC Investigation
structural Elements Recovered from the WTC Buildings

Source: NIST. Figure 3-6. (a) Characteristic stenciling found on the lower portions of the exterior

column panels for sample C-14. (b) Characteristic stenciling found on an interior core column for sample B-6152.

NISTNCSTAR 1-3B, WTC Investigation 15
a) 63

63

63 65 _ 6x 63 6x 65 6x 67 67 69 69

ix5« ® co|) @) (ip @i $p 3» @' @ ^ !@' & ® f@< ©@)

5x @

47®'

^6969

b) 563 569

«^569

Source: McAllister 2002 ;® 570

Figure 3-7. Schematic sliowing derrick divisions that

hoisted the specific columns for (a) WTC 1 and (b) WTC 2. The "x" signifies the information that was not readable.

NISTNCSTAR 1-3B, WTC Investigation
structural Elements Recovered from the WTC Buildings

Of the 42 positively identified exterior panels, 25 had specific markings giving all the information needed

(building, column, floors) to locate the structural element within the buildings from one or both codes

(i.e., stampings or stencils). The flange stampings, which indicated the specified yield strength and

column type, were used to confirai the findings (Tables 3-6 and 3-7). The only deviation noted was that 100 ksi steel was substituted for the 85 ksi and 90 ksi grades that were specified. This can be observed in Table 3-6 for samples B-1043, B-1044, C-10, and M-lOb. This substitution is consistent with PANYNJ

documents of the construction period, indicating that 100 ksi steel was used for all steel specified as 85 ksi or 90 ksi. (See NIST NCSTAR 1-3 A, Contemporaneous Structural Steel Specifications.)

Seventeen other panels were positively identified using a combination of the stampings, including the specified minimum yield strength (Table 3-8) and column type (Table 3-9), the stenciled derrick division

number (Table 3-8), or association to another panel, as follows:

• ASCE-2 : No information was available signifying the panel identification as only the one

outer column was recovered. The flange stampings indicated that the column was of the 356

type with 50 ksi steel. The column had large floor truss seats that fit seat detail 4410 or 4424. Reviewing the building design drawings, seven panels meet the criterion that the left- most column (when viewed from inside the building looking out) of the panel had the 356 -

50 combination (Table 3-10). Of these, only one panel had the proper floor truss seat identifying the panel as B330: 40-43.

• C-10: The stampings indicated that the center column line number was 45 1 and the panel

spanned floors 85 through 88, but the building identification information was obscured by a weld bead. The building can be identified by a derrick division number in the 50 series,

which corresponds to WTC 1 (Fig. 3-7). (Note that the flange stampings indicated that the

steel used is 100 ksi, while the building design drawings indicated that 85 ksi was specified.

As mentioned above, substitution of the specified 85 ksi, as well as the 90 ksi grades, by

100 ksi steel was approved.)

• C-24 : This piece was readily identifiable as a mechanical or service floor due to the non- uniform width of the columns. Unfortunately, only the upper portion of the panel was

recovered, and thus no stampings were found. However, the end connections to these floors were welded in addition to the typical bolting. In doing so, the end plate and a small portion

of the column from the panel above this piece remained after the collapse, and the stamping

of "B 203 77-78" identifying the panel above this sample was clearly visible.

• C-55 : The stampings indicated that the center column line number was 209 and the panel

spanned floors 94 through 97, however, no building information was observed. By reviewing

the flange stampings (Table 3-8), the piece was determined to belong to WTC 1.

• C-92 : Stenciling on the piece indicated that it was from WTC 2, floors 93 through 96. However, the center column line number was partially obscured, with 1 3x visible. By

reviewing the flange stampings (Tables 3-8 and 3-9), the piece center column line number

was determined to be 130.

NIST NCSTAR 1-3B, WTC Investigation 17
Chapter 3

Table 3-6. Specified and observed minimum yield strengths for positively identified

exterior column panels.^

NIST Name BIdg Colmmi Floors

Specified Minimum Yield (ksi) Stamping Observed

Column 1 Colurnn 2 Column 3 Column 1 Coluirm 2 Column 3 ASCE-2 VfTC 2 329 40-43 50 50 50 50 NA NA

B-1024 YfTC 2 154 21-24 50 50 50 NA 50 NA

B-1043 YfJC 2 406 40-43 85 90 90 ,J00_ 100 100 B-1044 WTC2 409 40-43 85 80 85 100 80 100 C-10 WTC 1 451 85-88 85 85 90 100 100 100 C-13 or S-11 and C13a orS-19 "WTC 2 200 90-92 100 100 100 100 NA NA

C-14 orS-18 V^rrc 2 300 85-87 100 100 100 NA NA NA

C-18 VfTC 2 230 93-96 55 55 55 55 5f 55 C-22 VfTC 1 157 93-96 80 75 80 80^ NA 80

_C-24 Vi/TC 2 203 74-77 100 100 100 NA NA NA

C-25 YfTC 1 206 89-92 80 80 80 80 NA NA

C-40 v^rrc 1 136 98-101 60 60 55 NA 60 55 C-46 WTC 2 157 68-71 _ 80 70 65 SO NA 65 C-48 or S-5 VfTC 2 442 91 - 94 65 65 NA 6f NA

C-55 YfTC 1 209 94-97 70 70 70 NA 70 _

C-89 WTC 2 2J^ _ 50 50 55 NA NA NA

C-92 YTTC 2 130 93 - 96 60 60 60 60 NA NA

C-93 YfTC 1 339 99-102 _ _^60_^ 60 60 NA 60 NA

cc Yrrc 1 124 70-73 50 ""50 " 50 NA 50 50 K-1 orK-13 v^rrc 1 209 97-100 60 60 60 60 60 60 K-2 or K-40 v^rrc 1 236 92-95 65 65 65 NA 65 NA

M-2 vrrc 1 130 96-99 55 55 55 55 55 55 M-lOa YITC 2 209 82-85 85 85 85 NA NA NA

M-lOb WTC 2 206 83-86 85 85 85 100 100 NA

M-20 WTC 1 121 99-102 55 55 55 NA 55 55 ^M-26 VfTC 1 130 90-93 50 55 50 NA 55 _ 50 :m-27 WC 1 130 93-96 50 55 _ 55 50 55 NA

iM-28 WTC 2 345 98 - 101 70 70 70 NA NA NA.

:M-30 WTC 1 133 94-97 55 55 55 NA 55 55 N-1 WC 1 218 82-85 70 75 75 70 75 NA

|N-7 or M-3 WC 1 127 97-100 55 55 60 55 55 60 :N-8 or M-7 WTC 1 142 97-100 60 60 60 NA 60 NA

:N-9 or M-8 VTC 1 154 101-104 55 55 55 55 55 NA

;N-10 orM-15 YJTC 1 115 89-92 55 55 55_ _ NA 55 _ 55 iN-12 orM-13 WTC 1 206 92-95 75 75 75 NA 75 75

!N-13 orM-14 VTC 1 130 99-102 55 55 55 NA_ NA NA

IN-99 or M-16 mc 1_ _ J48 99-102 65 65 65 65 NA

IN-101 orM-21 WTC 1 133 100-103 55 55 55 55 55 55

iS-1 or EE VTC 1 433 79-82 70 70 70 NA 70 70

iS-9 or C-63 VTC 1 133 97-100 55 55 55 55 55 55

:S-10 or C-17 WTC 1 224 92-95 70 70 70 70 70 NA

;S-14 orC-20 WTC 2 218 91-94 65 65 70 65 65 70

a. Columns 1, 2, and 3 are viewed left to right as viewed from the inside of the building.

Key: NA, information not available.

18 NISTNCSTAR 1-3B. WTC Investigation
structural Elements Recovered from the WTC Buildings

Table 3-7. Specified and observed column types for positively identified exterior

column panels.^

NIST Name Bldg Column Floors

Specified Column Type Stamping Observed

Column 1 Column 2 Column J Column 1 Colurrm 2 Column 3

Vv i 4U-'4 J 356 356 356 356 1-JA NA

RL> - 11 n7d U <iH VJTC* 1 9 1 lA 149 150 152 149 150 i 152

r>- J. yJHJ vv i tUu 335 334 334 335 334

1 334

V V i «i 4U-4 J 335 335 335 335 335

1 335

r* 1 n IJITTP W 1 1 1 n J

1

9.9. 120 120 120 120 120 \_ 120 u- i J or o- 1 1 anci UiJa or b-ib

A;\rrc 2 200 90-92 120 520 120 120 NA NA

C-14 or S-IS WTC 2 300 85-87 122 522 ]l20 NA^ na" NA

C-18 VflC 2 230 93-96 120 120 120 12Cl]J7 l"j207'..lLlI 120 C-22 v^rrc 1 157 93-96 120 120 120 NA " ' "

120 C-24 Arrc 2 203 74-77 325 325 325 Bottoms missing C-25 TArrc 1 206 89-92 120 120 120 120 NA NA

C-40 WTC 1 136 98-101 121 121 121 NA 121 i 121 C-46 WTC 2 157 68-71 126 128 129 126 NA ! 129 C-48 or S-5 WTC 2 442 91 - 94 120 120 120 NA 120 NA

C-55 virrc 1 209 94-97 120 120 120 NA 120 NA

C-89 WTC 2 215 12 - 15 147 145 143 NA NA NA

C-92 WTC 2 130 93 - 96 124 123 123 124 NA NA

C-93 WTC 1 339 99 - 102 121 121 121 NA 121 NA

WTC 1 124 70-73 133 133 ^133 NA 133_ 133 K-1 or K-13 WTC 1 209 97-100 120 120 120 120 120 T 120 K-2 or K-40 WTC 1 236 92-95 120 120 120 NA 120_ _i NA

M-2 TATC 1 130 96-99 122 122

~ '122" ' i22 122 122 M-lOa WTC 2 209 82-85 120 120 120 NA NA NA

M-lOb WTC 2 206 83-86 120 120 "120 120 120 NA

M-20 WTC 1 121 99-102 120 120 120 NA 120 120 M-2f5 WTC 1 130 90-93 125 125 125 NA 125 125 M-27 WTC 1 130 93-96 124 J_23 1_2J 124 123 J NA

M-28 WXC 2 345 98 - 101 120 120 120 NA NA

M-30 WTC 1 133 94-97 123 123 123 NA 123 123 N-1 WTC 1 218 82-85 123 123 123 123 123 NA

N-7 or M-3 "WTC 1 127 97-100 121 _ _ _ _121 121 121 121 121 N-8 or M-7 WTC 1 142 97-100 121 '"121

121 NA 121 NA

N-9 or M-8 "WTC 1 154 101-104 120 120 120 120 I 120 NA

N-10 or M-15 lATC 1 115 89-92 125 125 125 NA 125 125 N-1 2 or M-13 WTC 1 206 92-95 120 120 120 NA 120 120 N-1 J or M-14 WTC 1 130 99-102 I

121" 121 120 NA NA NA

:N-99 or M-16 WTC 1 148 99-102 120 120 __j20 120 120 NA

N-101 or M-21 WTC 1 133 100-103 120 120 120 120 120 120

S-1 or EE WTC 1 433 , 79-82 123 123" 123 NA 1 123 1 123

S-9 orC-63 WTC 1 133 97-100 122 122 122 122 122 122 S-10 or C-17 WTC 1 224 92-95 120 120 120 120 120 NA

S-14 or C-20 WTC 2 218 91-94 120 120 120 120 120 120

a. Columns 1, 2, and 3 are viewed left to right as viewed from the inside of the building.

Key: NA, information not available.

NISTNCSTAR 1-3B, WTC Investigation 19
Chapter 3

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20 NISTNCSTAR 1-3B, WTC Investigation
structural Elements Recovered from the WTC Buildings

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NISTNCSTAR 1-3B, WTC Investigation 21
Chapter 3

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22 NISTNCSTAR 1-3B, WTC Investigation
structural Elements Recovered from the WTC Buildings

• C-93 : The stampings indicated that the center column line number was 339 and the panel

spanned floors 99 through 102; however, no building information was observed. By

reviewing the flange stampings (Table 3-8), the piece was determined to belong to WTC 1

.

• CC: The stampings indicated that the center column line number was 1 24 and the panel

spanned floors 70 through 73; however, no building information was observed. By reviewing

the flange stampings (Table 3-8), the piece was determined to belong to WTC 1.

• K-1 : The stampings indicated that the center column line number was 209 and the panel

spanned floors 97 through 100; however, no building information was observed. By

reviewing the flange stampings (Table 3-8), the piece was determined to belong to WTC 1

.

• K-2 : The stampings indicated that the center column line number was 236 and the panel

spanned floors 92 through 95; however, no building information was observed. By reviewing

the flange stampings (Table 3-8), the piece was determined to belong to WTC 1.

• M-2: No information was available from the stampings at the base of the middle column,

and very little information was recovered from the stenciling on the spandrel. A derrick

division number of <63> was observed, placing the element in WTC 1 (Table 3-8). The only

other information was - 9, indicating that some portion of the panel was located in the

90s-floor-level range. The flange stampings from the recovered piece specified that all three

columns were of the 122 type, with F,. 55 ksi steel. In addition, columns 1 and 3 had floor

truss seats, while column 2 had gusset plates for the diagonal bracing straps. Reviewing the

building design drawings, it was found that five panels meet the 122 column type, with 55 ksi

steel in the 90s range (Table 3-11). Of these, only two panels had columns 1 and 3 with floor

truss seats (130: 96 through 99 and 330: 96 through 99). As shown in Fig. 3-7, the derrick

division of <63> identifies the panel as 130: 96 through 99.

• M-lOa: The sample was identified solely by association to another panel (bolted spandrel

connection). The sample M-10 retrieved by SEAoNY was actually composed of pieces from

two different exterior column panels (Fig. 3-8). Therefore, with the positive identification of

M-lOb via the stampings and stencils, M-lOa's connection to it allowed its identification as WTC 2,209: 82 through 85.

• M-2

8

: The stampings indicated that the center column line number was 345 and the panel was located in WTC 2. However, the markings of the floors spanned were partially obscured;

9x-lxx. By reviewing the building design drawings, the only panel that could fit spanned

floors 98 through 101.

• M-30: The stampings found were x33 94-97, where the "x" signifies missing information

due to a weld bead running across this area. Thus, the building and exact center column line numbers were unknown. However, a derrick division number of <65> was visible on the

interior spandrel. From this information, as well as the specified minimum yield strength

(Table 3-8) and column type (Table 3-9), M-30 was determined to belong to WTC 1. with a center column line number of 133.

NISTNCSTAR 1-3B, WTC Investigation 23
Chapter 3

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24 NISTNCSTAR 1-3B, WTC Investigation
Structural Elements Recovered from the WTC Buildings

mBottom of columns

M-10a M-10b

Figure 3-8. Schematic showing the sample M-10 as two separate exterior column panels,

M-10a and M-10b.

• N-1 : The stampings indicated that the columns spanned floors 82 through 85; however, no

building information was observed and a weld bead ran through the middle of the center column line number yielding only "2x8." By reviewing the building plans, only column line 218 spanned the floors specified and the flange stampings (Tables 3-8 and 3-9) indicated that the piece belonged to WTC 1.

• N-7 : The stampings indicated that the center column line number was 127 and spanned floors 97 through 100, however, no building information was observed. By reviewing the flange

stampings (Table 3-8), the piece belonged to WTC 1.

• N-12 : The stampings found were x06 92-95 where the "x" signifies missing information due

to a weld bead running across this area. Thus, the building and exact center column line numbers were unknown. However, a derrick division number of <69> was visible on the

interior spandrel. From this information, as well as the specified minimum yield strength

(Table 3-8) and column type (Table 3-9), it was determined that N-12 belonged to WTC 1, with a center column line number of 206.

• S-10 or C-17: The stampings indicated that the center column line number was 224 and the

panel spanned floors 92 through 95; however, no building information was observed. By

reviewing the flange stampings (Table 3-8), the piece was determined to belong to WTC 1

.

NISTNCSTAR 1-3B, WTC Investigation 25
Chapter 3

In addition to the overall images taken for record-keeping purposes, the exterior column panels were mapped to indicate how much of the panel was recovered after the collapse. Figure 3-9 displays

schematics of typical exterior panels recovered, and Figs. 3-10 and 3-1 1 show these maps, with the

recovered portion indicated, for the identified samples from WTC 1 and WTC 2, respectively. Special note should be given to the fact that these diagrams are drawn as if viewed from the outside of the

building. B-1043, B-1044, and C-24 were samples located at the mechanical floors of the building. C-13

and C-13a (pieces of the same exterior panel) and C-14 were exterior wall panels located at the comer of

the building.

For the 12 samples identified as core column material (Table 3-3), all but 2 were clearly marked.

Figures 3-12 and 3-13 show the portion of column recovered for each individual column from WTC 1 and WTC 2, respectively. Sample C-30 had markings that clearly indicated the building and column;

however, the floors were partially obscured: "x04-10x." As the 24 ft section has both connector ends, it spanned only two floors and fit with the floor levels of 104-106. The second sample was C-88b, which

did not have any stampings or markings, but was welded to C-88a (identified by stampings). A final sample, C-83, was also found among this group. While no markings were found on the sample, it was

recorded as a core column due to its shape, which was very similar to C-90.

There were 1 3 other wide flange sections that had stampings and/or markings that did not correspond to the code as discussed above (Table 3^). Instead, there were typically three distinct grouping of numbers

and/or letters. Two examples are:

Sample C-44: "59 S 563"

Sample M- 17: "163 9 62"

One piece, C-26 (Fig. 3-14), was distinct among this group in that it was composed of three wide flange

sections bolted together at two different angles. The markings on the piece indicated that the wide flanges were 50 ksi steel and came from the 107th floor of WTC 1. Reviewing design drawings, it was found that

this piece was a component of the framed floor outside of the core. The as-built location of the other

1 2 components could not be determined nor confirmed that they were part of the structural steel used in the WTC towers.

Floor trusses were also recovered; however, attempts to identify their specific as-built locations within the

buildings were not successful. No stampings were found. Of the 23 pieces held by NIST, 8 are of

significant size but are badly tangled and twisted as a result of the collapse and subsequent handhng of the

material. The remaining pieces consist of shorter sections of chord and rod material in addition to welded

sections that connected the trusses to the floor seats.

At present, there are seven samples from WTC 5, all in the GZ-series (see Table A-10). These are coupons that were removed at the WTC site and held by Gilsanz Murray Steficek, LLP. They were

subsequently sent to NIST once the Investigation officially began.

No structural elements have been positively identified from WTC 7. However, the columns were

fabricated from conventional 36 ksi, 42 ksi, and 50 ksi steel that complied with ASTM International

specifications.

26 NISTNCSTAR 1-3B, WTC Investigation
structural Elements Recovered from the WTC Buildings

Outside of building looking in at panel

Column

Spandrel

Typical Exterior Panel

Outside of building looking in at panel

Column

Spandrel

Typical Mechanical Floor Panel

Outside of building looking in at panel

Column

Spandrel

r

Typical Corner Panel

Figure 3-9. Schematics displaying the various types of exterior column panels.

NISTNCSTAR 7-36, WTC Investigation 27
Chapter 3

Outside of building looking in at panel

JUU

C-10

A451 : 85-88

Un-recovered

portion

Outside of building looking in at panel

C-22

LI

A157: 93-96

Outside of building looking in at panel Outside of building looking in at panel

C-25 C-40

A206: 89-92 A136: 98-101

Figure 3-10. Exterior column panel maps indicating the portion of the specific

exterior column panel section recovered from WTC 1.

28 NISTNCSTAR 1-3B, WTC Investigation
Structural Elements Recovered from the WTC Buildings

Outside of building looking in at panel

C-55

A209: 94-97

Un-recovered

portion

Outside of building looking in at panel

J

CC

A124: 70-73

Outside of building looking in at panel

C-93

A339: 99 - 102

Outside of building looking in at panel

K-1

Also labeled as

K-1

3

L

A209: 97-100

Figure 3-10. Exterior column panel maps indicating the portion of the specific

exterior column panel section recovered from WTC 1 (continued).

NISTNCSTAR 1-3B, WTC investigation 29
Chapter 3

Outside of building looking in at panel

K-2

Also labeled as K-40

A206: 92-95 Un-recovered

portion

Outside of building looking in at panel

M-20

A121: 99-102

Outside of building looking in at panel

M-2

A130: 96-99

Outside of building looking in at panel

M-26

A130: 90-93

Figure 3-10. Exterior column panel maps indicating the portion of the specific

exterior column panel section recovered from WTC 1 (continued).

30 NISTNCSTAR 1-3B, WTC Investigation
structural Elements Recovered from the WTC Buildings

Outside of building looking in at panel

M-27

A130: 93-96 Un-recovered

portion

Outside of building looking in at panel

M-30

A133: 94-97

Outside of building looking in at panel Outside of building looking in at panel

N-1 N-7

A218: 82-85

A127: 97-100

Figure 3-10. Exterior column panel maps indicating the portion of the specific

exterior column panel section recovered from WTC 1 (continued).

NISTNCSTAR 1-3B, WTC Investigation 31
Chapter 3

Outside of building looking in at panel

N-8

Also

labeled as M-7

A142: 97-100

i Un-recovered

portion

Outside of building looking in at panel

N-9

r

Also labeled as M-8

A154: 101-104

Outside of building looking in at panel Outside of building looking in at panel

N-10

N-12

Also labeled as M-13

All 5: 89-92

A206: 92-95

Figure 3-10. Exterior column panel maps indicating the portion of the specific

exterior column panel section recovered from WTC 1 (continued).

32 NISTNCSTAR 1-3B, WTC Investigation
structural Elements Recovered from the WTC Buildings

Outside of building looking in at panel

N-13

A130: 99-102 Un-recovered

portion

Outside of building looking in at panel

N-99

A148: 99-102

Outside of building lookinq in at panel Outside of building looking in at panel

N-101

Also labeled as M-21

S-1

Also labeled as EE

A133: 100-103

A433: 79-82

Figure 3-10. Exterior column panel maps indicating the portion of the specific

exterior column panel section recovered from WTC 1 (continued).

NISTNCSTAR 1-3B. WTC Investigation 33
Chapter 3

Outside of building looking in at panel

A133: 97-100

S-9

Un-recovered

portion

Outside of building looking in at panel

A224: 92-95

S-10

Figure 3-10. Exterior column panel maps indicating the portion of the specific

exterior column panel section recovered from WTC 1 (continued).

34 NISTNCSTAR 1-3B, WTC Investigation
structural Elements Recovered from the WTC Buildings

Outside of buildinR looking in at panel

ASCE-2

B330: 40-43

Mechanical Floor

Un-recovered

portion

Outside of building looking in at panel

Broken columns from

upper panel B-1043

• 3 bolts and

welds intact

B406: 40-43

Mechanical Floor

Outside of buildinu looking in at panel

B-1024

8154: 21-24

Outside of building looking in at panel

Broken columns from

B-1044

3 bolts and

welds intact

B409: 40-43

Mechanical Floor

Figure 3-11. Exterior column panel maps indicating the portion of the specific

exterior column panel section recovered from WTC 2.

NISTNCSTAR 1-3B, WTC Investigation 35
Chapter 3

Outside of building looking in at panel

C-13

Also labeled

as S-l 1

C-13 and

C-13a

(separated)

Also labeled

B200: 90-92

Corner Panel

Outside of building looking in at panel

C-18

:

B230: 93-96

Outside of building looking in at panel

C-14

Also labeled

as S-18

B300: 85-87

Corner Panel

Outside of building looking in at panel

C-24

B203: 74-77

Mechanical Floor

Figure 3-11. Exterior column panel maps indicating the portion of the specific

exterior column panel section recovered from WTC 2 (continued).

36 NISTNCSTAR 1-3B, WTC Investigation
structural Elements Recovered from the WTC Buildings

Outside of building looking in at panel

C-46

B157: 68-71

Outside of building looking in at panel

C-89

B215: 12-15

Outside of building lookinu in at panel

C-48

B442: 91-94

Outside of building looking in at panel

C-92

B130: 93-96

Figure 3-11. Exterior column panel maps Indicating the portion of the specific

exterior column panel section recovered from WTC 2 (continued).

NISTNCSTAR 1-3B, WTC Investigation 37
Chapter 3

Outside of building looking in at panel

M-lOa

B209: 82-85

Outside of building looking in at panel

M-28

L

B345: 98-101

Outside of building looking in at panel

M-lOb

L

B206: 83-86

Outside of building looking in at panel

S-14

Also labeled

as C-20

B218: 91-94

Figure 3-11. Exterior column panel maps indicating the portion of the specific

exterior column panel section recovered from WTC 2 (continued).

38 NISTNCSTAR 1-3B, WTC Investigation
Structural Elements Recovered from the WTC Buildings

Source: NIST. Figure 3-12. Core columns recovered from WTC 1. a) B-1011 (508A: 51-54),

lower 2 ft to 3 ft of built-up box column, b) B-6152-1 (803A: 15-18), lower

3 ft of built-up box column.

NISTNCSTAR 1-3B, WTC Investigation 39
Chapter 3

Source: NIST. Figure 3-12. Core columns recovered from WTC 1. c) B-6152-2 (504A: 33-36),

lower 2 ft of built-up box column, d) C-65 (904A: 86-89), lower 24 ft of wide

flange section (continued).

40 NISTNCSTAR 1-3B, WTC Investigation
structural Elements Recovered from the WTC Buildings

I ^ t

Source: NIST. Figure 3-12. Core columns recovered from WTC 1. e) C-71 (904A: 77-80), lower 16 ft of

wide flange section, f) C-80 (603A: 92-95), lower 13 ft of wide flange section (continued).

NISTNCSTAR 1-3B, WTC Investigation 41
Source: NIST. Figure 3-12. Core columns recovered from WTC 1. g) C-155

(904A: 83-86), lower 33 ft of wide flange section, and h) HH

(605A: 98-101), lower 16 ft of wide flange section (continued).

NISTNCSTAR 1-3B, WTC Investigation
structural Elements Recovered from the WTC Buildings

Source: NIST. Figure 3-13. Core columns recovered from WTC 2. a) C-88a (801 B: 80-83), lower 16 ft of

built-up box column and C-88b (801 B: 77-80), upper 8 ft of built-up box column.

NISTNCSTAR 1-3B, WTC Investigation 43
Chapter 3

b)

Source: NIST. Figure 3-13. Core columns recovered from WTC 2. b) C-90

(701 B: 12-15), entire length of built-up box column, and c) C-30

(1008B: 104-106) entire length of wide flange section (continued).

44 NISTNCSTAR 1-3B, WTC Investigation
structural Elements Recovered from the WTC Buildings

JXM^Mif,':' . , , _ __

Source: NIST. Figure 3-14. Structural element composed of three wide flange sections bolted

together. The component was found to be from the framed floor area outside of the core on the 107th floor of WTC 1 (sample was C-26).

NISTNCSTAR 1-3B, WTC Investigation 45
Chapter 3

This page intentionally left blank.

46 NISTNCSTAR 1-3B, WTC Investigation
Chapter 4

Structural Steel Elements of Special Importance

Of the 41 exterior column panels and 12 core columns positively identified, many were considered

especially important to this Investigation led by the National Institute of Standards and Technology

(NIST). Two major categories of steel are considered to be of special value:

• Samples located in or around the floors impacted by the airplane

• Samples that can represent 1 of 12 grades of steel specified for the exterior columns,

1 of 4 grades of steel specified for the core columns, and 1 of the 2 grades of steel for the floor trusses

4.1 SAMPLES located IN OR AROUND THE FLOORS IMPACTED BY THE

AIRPLANE

Interpretation of the photographic evidence revealed that damage to World Trade Center (WTC) 1 due to aircraft impact occurred from floor 94 to floor 99 and was bounded by columns 1 1 1 through 152. For

WTC 2, the impact area was lower with damage found from floor 77 to floor 85. While the damage

appears to be bordered by column lines 411 and 440, columns closer to the southeast comer of the

building may also have been affected. However, few images were obtained where smoke is not obscuring

this portion of the south face of WTC 2 to complete the analysis. From this information, NIST was able

to determine which perimeter panels and core columns could be used to comment on damage and possible

failure mechanisms in this area. Figure 4-1 shows the sample overlay of the exterior panels in NIST's

possession in and around the impact zone of WTC 1. Samples C-80 and HH, both core columns, were

also identified as residing near the impact zone. The recovered portion of each column is approximately

represented in this image. Unfortunately, there were no similar corresponding exterior panels for WTC 2,

but two core columns were recovered (Fig. 4-2).

NISTNCSTAR 1-3B, WTC Investigation 47
Chapter 4

Figure 4-1. Interpreted column damage, from photographic evidence, to WTC 1, with

overlay of samples in NIST's possession. Samples shown represent recovered portions.

Core columns 603 and 605 are in the second row from the north face of WTC 1.

48 NISTNCSTAR 1-3B, WTC Investigation
structural Steel Elements of Special Importance

Damage in shaded area cannot be accurately determined. Note: Core column 801 is in the closest row to the south face of WTC 2. Figure 4-2. Interpreted column damage, from photographic evidence, to WTC 2,

with overlay of samples in NIST's possession.

4.2 SAMPLES REPRESENTING THE VARIOUS TYPES OF STEEL SPECIFIED

IN THE DESIGN DRAWINGS

The other grouping of samples that was deemed important was that which belonged to one of the different

grades of steel specified in the buildings' construction. The following minimum yield strengths, in ksi

(1 ksi equals 1,000 pounds per square inch), were specified for each structural element:

• Columns of the exterior panels: 36, 42, 45, 46, 50, 55, 60, 65, 70, 75, 80, 85, 90, and 100

• Core columns: 36, 42, 46, and 50

• Floor truss material: 36 and 50

NISTNCSTAR 1-3B, WTC Investigation 49
Chapter 4

From the recovered steel, sufficient representative samples from each important class of steels are available for a full examination (i.e., chemical, metallurgical, and mechanical property analyses). From

Table 4-1, it can be seen that 10 of the 14 types of steel specified for the columns are represented, and

10 of the 12 grades of spandrel material have been identified. Additionally, sample ASCE-3 (as-built

location in the building not identified) has a flange stamping of 45 for the minimum yield requirement,

which would increase the total number of perimeter column material types to 1 1 . One important note is that from the observed stampings of the recovered elements and other documents (see NIST

NCSTAR 1-2B), it appears that 100 ksi steel was substituted for the 85 ksi and 90 ksi grades in the

construction of the exterior panels (Table 3-6). Considering both column and spandrel material, samples

of all grades specified for the perimeter panels are available for metallurgical and mechanical property

evaluation. There are a total of 106 individual perimeter columns (97 coluirms with known as-built

locations and 9 columns from unidentified panels sections where the column type and minimum strength

values could be deciphered from the stampings located on the base of the columns) and 87 pieces of

spandrel material. Tables 4-2 and 4-3 list the specified minimum yield strength/gauge combinations

recovered for the columns and spandrels, respectively. While only two of the four grades of steels were

obtained (36 ksi and 42 ksi) for the core columns (Table 3-3), 99 percent of the total number of core columns were fabricated from these two grades. For the floor truss material, the samples could not be

identified as to their precise, as-built locations within the buildings. However, initial chemical and

mechanical property analyses have shown that both minimum yield strength materials specified have been

recovered.

50 NIST NCSTAR 1-3B, WTC Investigation
structural Steel Elements of Special Importance

Table 4-1. Listing of recovered exterior column panels with specified minimum yield

strengths and thickness for columns^ and spandrels.

NIST NAME Bldg Center

Col. #

Splice at floor Panel Type

COLUMN

1 COLUMN2 COLUMN

3 LOWER

SPANDREL 1 MIDDLESPANDREL

UPPER

SPANDREL

Col. tvnp * J r *^

Fv Col. tvnpFv Col. tvnpFv Gage Fv 1

yr>.yif I

Gage Fv Oage

(in)

Fv Lower|Upper (ksi) B-1024 V(/TC 2 154 1 "'4 300 152 50 150 50 149 50 1 9^1

1 . Z J jO 1i . 9^Z J jD 1 25 ''.fx ASCE-2 WTC 2 330 4 J 400 J_>D '^n jU 2JL£ £11 U . 7_»6 jO 11/

d

nU. Q?? 7 jO n J CC WTC 1 124 .' LI / J 300 1 J J

'^n JU 1 J J'^n jU f.n

U, ^OZ J jO U. ^OZD jD U, -'OZ^ '<(. JO M-26 WTC 1 1 30 on 7 J 300 1 9^ 1 Z J J Z J

1 9^

1 Z J DU U, J / J jD U J / J _»0 U. J Z-* jU M-27 AVTC 1 130 y J 70 300 1 9"^

1 Z J J J

1 OA 1 Z'H ^U U. J / J ju U J / J _iO l(. M-2 ViTC 1 130 rO QQ77 300 1 99 1 ZZ J J

1 9 9 1 ZZ J J1 99 I ZZ

C c J J 0 07c

U. J / j _)0 n 07c U J / J 49tZ U.J/.' ''.f.

1VI - J u WTC 1 133 Q77 / 300 1 Z_i

iTf 1 99 1 Z J CC

J J

1 O'y C C n '>7^. u. J y_) _»0 irb Q

^"yr A 0

C-18 WTC 2 230 !7_i yo 300 1 90 1 zU -> J

1 9n 1 ZU

CC

J J

1 90 IZU CCJJ U.J /j •4 J n '>7^

U. _) /D 49nZ 4.2 WT"C 1 154 1 n 1 1 U

1

300 11 9nZU c<

J J

1 9n I ZU <<; J J1 90 IZU JTC J J0 97f U. J / J 494Z U, J / J

9*^ JQ U. J / J JU

IVl - i» u l^TC 1 121 QQyy 1 m 300 1 9n izu 1 9ri

i ZU CC

J J

1 on CC

U. J /j 49'tZ 4J2 2£ N-13 WTC 1 130 QQyy 1lUzm 300 1 90 1 ZU J J

1 9

1

1 Zl CCJ J

1 9 1 IZl

1 90 IZU

CC

J J

0 '57<; U. j ij /49 4Z 4_2 Q 275 MIN - J.iniU

1

WTC 1 133 1 nn lUU iuJ 300 1 '>n

1 ZU CfJ J

1 9n 1 ZU J J CC

J J U. J }J 4hZ9 U. J / J JO nU. xi^ J / J JU WTC 1 1 33 1 nn

1 UU 300 1 99 1 ZZ J J

1 99 1 ZZ CC 1 99 1 ZZ J Jn ^7^ U.J /

J

9i^; jD nU, 97^ J /D 49tZ U, J / J JU

INw- 11 nU WTC 1 115 89 92 300 1 Z J 1 ZD <:< J J

1 9<: CC 0 97''; U.J /

J

jD n '57'^ U, J / J 494Z Q 275 4.2

r-4fi WTC 1 136 1 n 1 lU 1 300 1 ') 1 1 zl 1 f 1 1 Zl f^n uU 1 "0

1

-HH- 0 97^;

U. J / J 494Z n 97<;U. J IJ jD ri inc j i J

A 1

VV 1 (i 215 12 15 300 1 >1

1

_>_) Hj jU 1 ^'7 ^n i-j/j jO 1 J / j jO 1 J 0 jD

IN - / VV 1 O i 127 y y

1 nn

1 UU 300 1 z 1 OU 1 1 1 1 Z

1

CC

J J

1 9 1 1 Z i CC

J J

0 97^;

U, J / J 49HZ U /D 4nZ9 n ?t; 49

TITTr" W 9 1 <i 93 96 300 *^ n 1 T? 1 O/I 1Z4 *^n OU U- J / J A9 U J /D 49nZ Q 275 4.2

VV 1

1

339 99 102 300 ATI

1 Zl ^^n OU 1 0 1 AO n 97^ U. J / J 49•HZ Q

"^,7^ 4-2 Q 275 43

vv 1 U 1 9nQ 97 100 300 IzU du 1 ZU n DU 1 on 1 ZU f^O OU U. _i ; J 4nZ9 Q 07c 4_2 TIT Q 275 42

i^rrr VV i 1 i 236 92 95 300 120 1 on 1 zU OU tH:* U. J / J 49HZ U, J / J 49tZ Q 275 42

In -o Vl^ 1 i 149 97 100 ^00 1 1

1

Izl n DU 1 0 1 1 Zl OU 1 0 1 IZ I OU n 7"^^ U.J.'J 4 0 nZ 0 97<:

U. J /D 49nZ U. J / J 49 449 9

1

y4 300 1 "in IzU D J

1 "^n

1 zU 1 on n '57< U.J /j 4 ^J n 97';

U. J / J

4-^ 4D nU. Ti^ J fj 49

KT QQ In -77 iJtrTn 1 i|V 1 U 1 99 102 JUU IzU 0 J

1 on 1 ZU UJ 1 00 IzU 0 Jn 97'^

U. J / J TJ

n 97'^, U - J -' 49T Z 42

c; \A W 1 L- z

91 S? 91 94 JUU 1 on 1 ZU "Tn /U 1 9n 1 ZU AK 1 00 1 ZU 0 J

0 97'f U. J / J n 97^. U J V J 0 375 45

ivl-Zo 9 98 101 300 1 "-n

i zU .' U

1 on 1 zU /U 1 on IZU "70 /U n 97'^ U.J IJ 4^. 4 J Q 37c 4-£ Q

->75 /]5

L/- J" J IJITTP 1 1

1

209 94 9 / '^00 1 on 1 zU If] >v 1 20 n 97-^

U. J 0 4f^ AS, Q 275 45

Q 1 n o- 1 U V(f 1 U i 994 92 95 300 1 on 1 ZU /U 1 00 IZU 70/u 0 97'^ U.J / J ju nU. 97^ _i / J 46 Q 275 44

c; 1 o- J. 4?? 79 82 TOO 1 'ji

1 Z 3 /U 1 0'^1 Z J .' U

1 0"^ 0 497'\ U.4 J / J jU

' n -197^ 44 0 1375 45

KT 1 IN -

1

91 ?. 82 85 300 2i 1 ZJ tj 1 Z J / u U n J / J DU nU 97^ J /D JU 50 P Af, urrp 9 1 "^7

1 J / 68 71 300 izy 0 J 1 Z6 /U 1 Oi^ IZG COoU U, DZ J DD U, DZD U J

' 0 5625 65

KT 1 9

IN- IZ 92 95 JUU 1 ZU ^</ J

1 9n 1 ZU fj J 20 3£. -r? nU, 97^ J / J _>U nU. 97^ J / J 50 0 375 46 P 99 W 1 U 1

1 ^"7 93 96 JUU 120 80 120 75 120 SO 0.375 65 0 375 60 Q 275 46 P 9-^ 89 92 300 4^ ^ SS 120 80 0.375 55 0 375 55 [1 275 4§

B-1044 WC 2 409 40 43 400 335 85 335 80 335 85 0.9375 60 a'a a^a

' 0-9375 50 M-lOa lArrC 2 209 82 85 300 120 85 120 85 120 85 Or4^ 0.375 60 Q 275 M-lOb VlrTC 2 20d 83 86 300 120 85 120 85 120 85 0.375 60 Q 975 §0 Q 275 S&

C-10 WC 1 451 85 88 300 120 85 120 85 120

' 90 0.375 60 0.375 60 0.375 60 B-1043 ViTC 2 406 40 43 400 334 90 334 90 335 85 0.9375 65 a^a n/a 50^

C-24 WC 2 203 74 77 400 ^325 100 325 100 325 100 70 a^a a'"a 0.5625 80

C-13, 13a V^TC 2 200 90 92 210 120 100 520 100 m 4-00 a/'a 0 375 70 0.375 70

C-14 lATC 2 300 85 37 210 120 100 mQ 4-00 rJa. 0 375 75 Q -^75 7S.

a. Columns 1, 2, and 3 are left to right viewed from inside the building. Note: Strike through indicates section is missing.

NISTNCSTAR 1-3B, WTC Investigation 51
Chapter 4

Table 4-2. Strength/gauge combinations of perimeter

columns recovered by NIST.

Flange F, Flange Gauge Number of Columns Recovered and

(ksi) (in.) Identified bv NIST

45 1.75 1 50 0.5 2 50 0.5625 2

50 1.0625 2

50 1.8105 1 50 2.0625 1 50 2.125 1 50 2.25 1 50 2.5 1 50 2.625 1 55 0.25 12

55 0.3125 5 55 0.375 6

55 0.4375 3 55 0.5625 3 55 1.375 1 55 1.6875 1 60 0.25 5 60 0.3125 6

60 0.375 1 60 0.5 1 65 0.25 7 65 0.375 1 65 0.8125 1 70 0.25 7 70 0.4375 2 70 0.75 1 75 0.25 3 75 0.4375 2 80 0.25 3 80 0.625 1 80 1.1875 1 85- 100 0.25 12 85-100 0.5625 3 85-100 1.125 2

85-100 1.1875 3

52 NISTNCSTAR 1-3B, WTC Investigation
structural Steel Elements of Special Importance

Table 4-3. Strength/gauge combinations of spandrels

recovered by NIST.

iMimDer oi .^panarcis Kccovcrt'ti ny

36 3/8 16

36 9/16 3 36 1 1/4 3 36 1 3/8 3 42 3/8 24

45 3/8 7 46 3/8 4

50 3/8 5 50 7/16 2 50 1 5/16 2 3/8 2 60 3/8

60 1 5/16 1 65 3/8 1 65 9/16 1 65 5/8 2 65 15/16 1 70 3/8 2 75 3/8 1 80 9/16 1

NISTNCSTAR 1-3B, WTC Investigation 53
Chapter 4

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54 NIST NCSTAR 1-3B, WTC Investigation
Chapter 5

Summary

The National Institute of Standards and Technology has 236 samples from the World Trade Center

(WTC) buildings, the majority belonging to WTC 1 and WTC 2. These samples represent roughly a half

percent of the 200,000 tons of structural steel used in the construction of the two towers. The collection

of steel from the WTC towers is sufficient for determining the quality of the steel and for determining

mechanical properties as input to models of building perfomnance as sufficient representative samples

exist for all 12 grades of exterior panel material, 2 grades of the core column material (that represents

99 percent, by total number, of columns), and both grades for the floor truss material.

NISTNCSTAR 1-3B, WTC Investigation 55
Chapter 5

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56 NIST NCSTAR 1-3B, WTC Investigation
Chapter 6

References

Astaneh-Asl, A. 2002. World Trade Center Post-Disaster Reconnaisance and Perishable Structural

Engineering Data Collection, Final Report to National Science Foundation, UCB/CEE-Steel2002/04. University of California, Department of Civil and Environmental Engineering,

Berkeley, CA.

McAllister, T., ed. 2002. World Trade Center Building Performance Study: Data Collection,

Preliminary Obsen'ations, and Recommendations. FEMA403. Federal Emergency Management

Agency. Washington, DC, May.

NISTNCSTAR 1-3B, WTC Investigation
Chapter 6

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58 NISTNCSTAR 1-3B, WTC Investigation
Appendix A

Data on Recovered WTC Steel

A.1 DATABASE OF RECOVERED STEEL

Table A-1. List of all WTC steel elements recovered for NIST investigation.

In FEMA

report? NIST Name \ Type 1 Brief Description j Markings BIdq Column Floors Location

Y AA 2 full columns, thick walled 1 i PL — — —

i

Y (NSF) ASCE-2 ! c 1 full column 1 B330: 40:43 V'./TC2_ 330 40-43 ; PL

Y(NSF) ASCE;3 C J 1 column, bottom 1/3rd of left column J 1 PL

_ —

i

.! : - \

i

1 B-1011 RB

-H Heavy rectangular column 508A: 51:54 ] WTC 1 508 51- JFkyPL

B-1022 W Thick v^/ide flange with severe bend 205

B-1024 C 3 full columns B154: 21-24 WTC 2 154 21-24 JFK

B-1043 c Mechanical floor, 3 full columns _ _ B406: 40-43 yyTC2 406 40-43 JFK/PL

B-1044 _c Mechanical floor, 3 full columns 6409: 40-43 WTC 2 409 40-43 JFK/PL

B- 1044-1 0

Piece of crushed metal decking assoc

with B-1044 202

B-1075 w Wide flange i 205

B;2150 0 Pieces of aluminum sheathing i 202

\ 6-5004 BT Bowlie section ^ .

\ JFK/PL

I B-5007 BT Bowtie section JFK/PL_

B-6 152-1 RB Heavy rectangular column 803A: 15-18 WTC 1 803 15-19 PL

i B-6 152-2 RB Heavy rectangular column 504A: 33-36 M.L1.. ___504 _33-36 _ PL

Y BB C Single, thick column i 205

Y C-10 C Full panel 1 451:85-88 WTC 1 451 85-88 PL

Y C-11 c 2 columns, upper 2/3rds 205

^

Y C-13 orS-11 cc

Single rectangular column with large \ spandrels _

! B200: 90-92 WTC 2 200 90-92 PL

Y C-13a orS-19 c Partial of single column B200; 90-92 WTC 2 200 90-92 PL

Y C-14 or S-18 c 1 column, lower I^Grd \ 6300:85-87 V^TC 2 300 85-87 1 B

Y C-J5 c Partial of single column \ 205 Y _ C-16 c 1 column, upper 1j3rd i ! 205

Y C-IBa c Fell off during moving of C-16 ; 205 Y C-18 c 3 columns, bottom 2/3rds 6230:93-96 WTC 2 230 1 93-96 i PL

C-18 Associated B One vi'asher and nut i i Lab Y C-22 c 3 columins, lower 1/2, mangled \ A1 57: 93-96 \MC 1 1-157 : 93-96 1 PL

Y C-24 c

3 columns, upper 1.'2, columns change dimensions i B203: 74-77 WC 2 203 ; 7477; 205 Y C-25 i c 1 column, lower 1/2 1 A206: 89-92 VVfTC 1 206 89-92 PL

Y iC-26 iThree connected wide flanges 1604 & 605 (107) 64 Fy 50 i PL

Y ;C-28 1 c h column of unknown location 205

Y :C-28B CC iCorner column, in 2 pieces 205

y :C-29 w Wide flange 205 _ Y :(>30 or S-12_ .w Wide flange i 10086 x04 - lOx WTC 2 ! 1008 I104-IO6 PL

_Y |C-31 orS-7 ! w iWide flange 676 35 205 Y lc-32 ! c n column, upper 1/3rd 236 Y IC-35 i w IWide flange J

205 Y lC-40 \ c :2 columns, lower 2/3rds 1 A1 36: 98-101 iWTC 1 136 98-101 PL

NISTNCSTAR 1-3B, WTC Investigation 59
Appendix A

Table A-1. List of all WTC steel elements recovered for NIST investigation (continued).

In FEMA

renort? NIST Name Type Brief Description Markings BIdq Column Floors Location

Y C-41 c 1 column, lower 2/3rds 205 Y C-42 w Wide flange 205

Y C-43 c 1 column, lower 1/2 205

Y C-44 w

Wide flange, FEMA reported possible

core columns 59 S 563 PL

Y C-45 w

Wide flange, FEMA reported possible

core columns 15 S2 563

r~

PL

Y C-46 c Nearly 3 full columns B157: 68-71 WTC2 157 68-71 ^ PL

Y C-47 c 3 columns, upper 1/2 236 Y C-48 orS-5 c Nearly 2 full columns B442: 91-94 MC..2. 442 205 Y C-49 orS-6 c portion of 1 column 236 Y C-51 c 2 columns, upper 1/2 205 Y C-52 c 1 column, upper 2/3rds 205 Y C-53 J Floor truss PL

Y C-53B J Floor truss PL

i Y C-54 c

1 column, small piece with extended

outer web 205

j Y C-55 c 1 column, lower 1j'3rd 209: 94-97 WTC L 209 94-97 PL

Y C-60 w Wide flange, S-shaped 193 SI 57 PL

; _ Y C-61 w VWde flange 150 S 69 PL

; Y C-62 vv Wide flange 224 (S) <48> PL

Y C-64 c 1 column vi/ith a lot missing 205

^ C-65 or S-8 w V^/ide flange 904A (86-89) <52> PL

i Y C-66 or S-17 w Wide flange 205 Y C-67 c 1 columin, rest unknown 205 Y C-68 c 1 column, upper 1j'2 205 Y C-69 w Wide flange 205 Y C-70 w Wide flange 205 Y C-71 w Wide flange 904A 77-80 WTC 1 904 77-80 PL

Y C-72b _w Wide flange 205 Y C-73 c__ 1 column, upper 1/2 205 Y C-74 w Wide flange 205

Y C-75 c

Portion of 1 column and spandrel, rest unknown 236 Y C-76 w Wide flange 205

Y Ky-f f 2 columns from different panels attached at spandrel, 1/3rd of each 205

Y C-78 w Wide flange 205 VT DPKb Rectangular columm, FEMA reported possible core column

101 A 81 -85-87 -92 52 V^TC 1 PL

Y C-80 w

Vy/ide flange, FEMA reported possible

core columns 603A 92-95 <51> WTC 1 603 92-95 PL

Y C-81 w Wide flange 205 ^

1 Y C-82 w Wide flange __2q5

- -

V /MCIFS Y (IMc>r; Kb Heavy rectangular column, FEMA

reported as possible core column No ID, similar to other core column PL

1 Y(NSF) C-84 c 1 full column PL

1 Y (NSF) C-85 w Wide flange 205

I Y C-87 w Thick Wide flange 205 i

C-88a RB

Built-up box column, FEMA reported possible core column

801 B 80-83 WTC 2 801 80-83 PL

C-88b Built-up box column, vi'elded to C-88a 801 B 77-80 WTC 2 801 77-80

_^ pI I C88c 0 Broke off C-88 PL

1 Y|NSF) C-89 c 2 full columns B215: 12-15 WTC 2 215 12-15 PL i

60 NISTNCSTAR 1-3B, WTC Investigation
Data on Recovered WTC Steel

Table A-1. List of all WTC steel elements recovered for NIST investigation (continued).

In FEMA

report?

lilo 1 Maine Brief Description Markings Bidt) Column Floors Location

Y (NSF) C-90 RB

Heavy rectangular column, FEMA

reported as possible core column 701B 12- 15 WTC 2 701 12-15 PL

Y C-91 ] Ch Channel 236 Y C-92 C Partial of single column BI Sx: ?3-96 WTC 2 130 93-96 ...PL

Y C-93 c Partial of single column 339: 99- 102 WTC 1 i 339 99- 102

' PL

C-94 0

May be some type of brace,

rectangular box construction

- • -

PL

C-95 Ch Channel 236

C-96 Ch Channel 236

C-97 Ch Channel 238

C;£8 Ch Channel 236

C-99 _ Ch Channel 236

C-100 _ J Possible angle from a floor truss PL

C-101 RB thinner 78A 10 27 50 ~' PL

C-102 C Partial of single column 205

C-103 0 Square-tube construction PL

C-104 Possible angle from a floor truss

" —

PL

C-105 Ch Channel 236

c^ioe _ J Small piece of floor truss 202

C-107 Ch Channel — -•' 236

C-108 B Three sheared bolts _Lab C-109 B Single bolt sheared Lab c-jig B Bolt and nut Lab

c-rij B Bolt and wasner

'—

Lab C-112 B Single bolt sheared Lab

C-113 B Tv('o sheared bolts with washers '— Lab

C-114 B Sheared bolt with nut Lab

C-115 J Pig-tailed piece from floor truss Lab

C-116 H Damper

- - —

Lab

C-117 C 3 columns, lower 1/3 101-104 PL

C-118 Ch Channel 1 236 C-119A 0 Square-tube construction PL

C-119B 0 Square-tube construction ! PL

C-120 0 Square-tube construction i PL

C-121 0 Square-tube construction

| PL

C-122 J_ Piece of floor truss

|_ PL

C-123 w Small Wide flange \ r 205

p-124 Ch Channel \ 236

C-125 Ch Channel 236

C-126 W Wide flange 205

C-128 Ch Channel B

C-129 Ch Channel 236

C-130 W Wide Flange 205

C-131 J

Small portion of floor truss with cement i- - -

' 202

C-132 J Piece of floor truss , PL

C-133 c

1 column, bottom 1/3rd of unknown \ location \ 205

C-134 Ch Channel I 236 ,

C-135 0

May be some type of brace, i rectanqular box construction ! PL

C-137a J Piece of floor truss l PL

C-137b J Piece of floor truss 1 PI- C 137c J Piece of floor truss PL

C-137cl J Piece of floor truss 1 PL i

C-137f J Piece of floor truss i PL

NISTNCSTAR 1-3B, WTC Investigation 61
Appendix A

Table A-1. List of ail WTC steel elements recovered for NIST investigation (continued).

i InFEMA

i report? NIST Name Type Brief Description i Markinqs

. „ • . _ BIdq Column Floors Location \

C-138 W Small wide f ange ; 205 !

i C-139 Ch —1 - - Channel • 236 i C-140 J Piece of angle r PL i C-141 Ch Channel i 235 1 C-142 W Wide flange i 205 i C-143 Ch Channel s 236 1

u__.„ C-144 Ch Channel j 236 J

C-145 Ch Channel _

.

236 1 C-146a _ 0 Mangled ball of steel and concrete 1 202

J C-146b J Piece of floor truss | PL i C-147 Ch Channel

" 23B i C-148 Ch Channel 236

C-149 J Piece of floor truss PL

C-150 _ W Wide flange 205

G-151 J Piece of floor truss PL

C-152 Ch Channel 236

C-153 Ch Channel —236

C-154 RB Thin rectangular beam with supports 825: 107-108 52 PL

C-155 W Wide flange 904A 83-86 WTC 1 904 83-86 PL

C-156 0 Square-tube construction PL

Y CC C 2 full columns i 124:73-70 wrc i_ 124 _70;73_ PL

Y DD c

1 Column, spans 1 floor and has end j plates on both ends | 205

Y FF c Single, thick column i 205

GZ-1 Cn5

Received from D, Sharp, coupon from | Bldg« Lab

:G2-2 Cn5

Received from D. Sharp, coupon from j Bldg#5 I Lab

GZ-3 Cn5

Received from D Sharp, coupon from 1 Bldg« Lab

;G2r4 Cn5

Received from D Sharp, coupon fromi ; Bldg#5 Lab

IgZ-5 Cn5

Received from D Sharp, coupon from 1 Bldg« Lab

\glb Cn5

Received from D Sharp, coupon from | BIdgfS Lab

\gZ7 Cn5

Received from D. Sharp, coupon from i BIdgAS { Lab

1 i i

1

Y HH or S-2 W

* i Wide flange. FEMA reported possible i core column 605A 98-101 WTC 1 605 98-101 • PL

Y \Kr^ or K-13

I C, 3 columns, lower 1/3rd j 209: 97-100 \VTC 1 209^ 97-100 202

i Y ll« or K-40 ( _...c_ 1 column, lower 2/3rds \ _ 236: 92-95 WTC^I 236 _ 92§5__ PL

Y kio Cn

Flange coupon received from Gross,

July 29, 2002 Lab

1 Y 1 Cri

Flange coupon received from Gross, j July 29, 2002 | Lab

1 Y |Kr12 ] Cn^

Flange coupon received from Gross,

July 29, 2002 1 Lab

Y !K-13 Cn

Flange coupon received from Gross, \ July 29, 2002 J

1 Lab

62 NISTNCSTAR 1-3B, WTC Investigation
Data on Recovered WTC Steel

Table A-1. List of all WTC steel elements recovered for NIST investigation (continued).

In FEMA

report?

Y

NIST Name

K-14

Type Brief Description

„ Markings BItly Culurrm Floors Location

Cn

Flange coupon received from Gross,

July 29,2002 Lab

Y K-15 Cn

Flange coupon received from Gross,

July 29,2002 Lab

Y K-16 C

1 full colun-m, thick, looks very corroded PL

K-16a _ __C

^ Fell off of K-16 while moving PL

_ __ __Y K-ie^ Cn

Flange coupon received from Gross,

July 29, 2002 Lab

Y K-19a Cn

Flange coupon received from Gross,

July 29,2002 Lab

Y K-19b Cn

Flange coupon received from Gross,

July 29, 2002 Lab

_Y K-50a 0

Rectangular slab of steel v/ith bolts, received from D Sharp, SEAoNY Lab

Y K-50b 0

Rectangular slab of steel with bolts, received from D Sharp, SEAoNY Lab

Y K-50C 0

Rectangular slab of steel with bolts, received from D. Sharp, SEAoNY Lab

Y M-2 C Full panel -9 <63> : WTC 1 130 96-99 PL _

Y M-4 or M-5 c 3 columns, upper 2/3rds 205

Y M-lOa c 3 columns, unknown location B209: 82-85 WTC 2 206 82-85 PL Y M-lOb c 3 columns, lower 1.'2 B206; 83-86 v\n"C2 206 83-86 PL

, . . Y

tv1-1J_ _ w Wide flange 205

^ Y M-17 w

Wide flange or I-beam, 1 'flange, 2' web, 50-60' long 163 (9) 62 205 M-17a 0 Fell oft' of Iv1-17 while moving 202

M-18 RB Large box beam, 19" x 21" x 17.5' long 205

tyi-19 C 2 columns, upper 1/3rd 205 M-20 C 2 columns, lower 1/3rd A121: 99-102 WTC 1 121 99-102 PL

M-22 RB

Large box beam, 19" x 26.5" x 9.5' long 205

M-23 W Possibly part of Wide flange or I-beam F2010 PL

1 _M-24 Ch Channel 236

M-25 J Small piece of floor truss 202 M-26 C 3 full columns A130; 90-93 yvTC 1 130 90-93 PL

M-26 associated B 8 bolts and a nut Lab M-27 _C 2 columns, lower 3/4ths A130: 93-96 WC 1 130 93-96 202 . M-28 C 3 columns, lower 1/4th B345: 9x - 1 XX WTC 2 . 345 ; 98 -101 PL

M-29 0 5 ft piece of strapping

: 202

M-30 c 2 columns, lower 1/3rd ^33; 94-97 WTC± 133 202

M-30 associated 0

Pieces of glass, plexiglass, other

rubble Lab

i M-31 J Pieces of floor truss \ Lab M-32 J Pieces of floor truss Lab M-33 w Wide flange 205

M-34 Ch Channel B M35 cc Corner column 205 MSB J Thick angle PL m:7 w VWde flange 130 (B?-92) <50> 205

iM-38 L_,..,.W _ Wide flange Fy42 PL

NISTNCSTAR 7-36, WTC Investigation 63
Appendix A

Table A-1. List of all WTC steel elements recovered for NIST Investigation (continued).

In FEMA

report? NIST Name Type Brief Description Markinqs BIdg Column Floors Location

Y N-1 C_

C

2 full columns i 2 8; 82-35 WTC 1 218 82-85 PL

Y N-3 1 column, upper 1;2 | 236 Y N-4 c 1 column, middle 1/3rd 236 Y N-5 0 Part of spandrel plate vi/ith bolts

j PL

Y N-6 c 1 column, length of spandrel, crushed I 236 1 Y (as M-3) N-7 or M-3 c 3 full columns 1 127:97-100 WTC1 127 97-100 PL

j Y (as M-7) N-8 or M-7 c Full panel A142: 97-100 WTC 1 142 97-100 PL _j

Y (as M-8) W-9 or M-B c

Almost full panel, missing lower 1/3rd

of 1 column A154; 101-104 y\,TC 1

_

_ 154 101-104 PL 1 N-10 orM-15 c 2 columns, lower 2/3rds A115: 89-92 WTC 1 115 89-92 PL 1 Y (as M-9) N-11 or M-9 c 3 columns, upper 2/3rds | 2D5 ! m N-12 or M-13 c 2 full columns i 06: 92-95 WTC 1 206 92-95 PL

m......... N-13 orM-14 _c 3 columns, lower 1/3rd A130; 99-102 WTC 1 130 99-102 5

Y (as M-

, 16) N-99 or M-16 c

Almost full panel, missing lower 1/3rd

of 1 column _ A1 48: 99-102 VVTC 1^ 1 48 99-102 PL

N-101 orM-21 _ c 3 full columns A133; 100-103 ^WTC 1

_ 133 100-103 PL ,;Y (as C-19) N-N or C-19

' "c 1 column, lower 1/2 205

1 Y (as EE) S-1 or EE c 2 columns, lower ^^'3r<i A433: 79-82 WTC 1 433 79-82 PL

Y (as C-50) S-3 or C-50 c 1 column, unknown 1/2 205 JJas C-63) S-9 or C-63 c Full panel A133: 97-100 WTC 1

__ 133 97-100 PL

]Y (as C-17) S-10 or C-17 c 2 columns, lower 1/2 224; 92-95 WTC 1 224 92-95 PL

lY (as C-20) S-1 4 or C-20 c Full panel B21B: 91-94 WTC 2 218 91-94 PL

SM2 w I-beam 205

L

[ YJas N-2) T-1 or N-2 J Floor truss material 202

U-5 c 3 columns, upper 1/4 236

U-15 c Partial of single column 205

U-25 0 Unknown Wide flange with concrete <North> 84-155 A8 Div2 205

Y W-14A or A w Heavy Wide flange 205

1 Y _ W;14B^ w_ _ Heavy Wide flange r PL

„.. NSF: Pieces conlnbuled by A. .Asteneh salvaged under NSF contract Key: 202, Bldg. 202, high bay; 205, BIdg. 205, parking lot; 236, Bldg. 236. parking lot; B, bolt; BT, bowtie section of exterior wall; C, flat wall, exterior column panel section; CC, comer panel section of exterior wall; Ch, channel; Cn, coupon of exterior column; Cn5, coupon from WTC 5; H, hanger; J, floor truss; NSF. pieces contributed by A. Asteneh salvaged under NSF

contract; O. other; RB, rectangular, built-up box column; W, wide flange section; Lab, Bldg. 223, Rm B253; JFK, Hanger 17, JFK Airport; JFK/PL, Main piece at JFK, portion at NIST. PL, Bldg. 202, parking lot;

64 NISTNCSTAR 1-3B. WTC Investigation
Data on Recovered WTC Steel

Table A-2. List of identified exterior pane sections.

\\n FEMA report? NISTName Type Brief Description Msrkin ys BIdg Pnlutnn Y (NSF) ASCE-2 C 1 full column B330 40-43 V'./TC 2 530 40-43

j.

B-1024 C 3 full columns 8154: 21-24 WTC 2 154 21-24 B-1043 c Mechanical floor, 3 full columns B406. 40-43 WTC 2 405 40-43 B-1044 c Mechanical floor. 3 full columns 8409 40-43 WTC 2 409 40-43

Y C-10 c Full panel — —.. 451 : 85-88 WTC 1 451 85-88 Y C-13 or S-11 CC Single rectangular column with large spandrels B20D 90-92 WTC 2 200 90-92 Y C-13a or S-19 c Partial of single column B200: 90-92 WTC 2 200 90-92 Y C-14 orS-18 c 1 column, lovi/er 1 /3rd B300: 85-87 WTC 2 300 85-87

r Y C-18 c 3 columns, bottom 2/3rds B230: 93-96 V^n'C 2 230 93-96 Y C-22 c 3 columns, lower 1/2, mangled A157: 93-96 WTC 1 157 93-96

1 Y C-24 c 3 columns, upper 1/2, columns change dimensions B203: 74-77 WTC 2 203 74-77 Y C-25 c 1 column, lower 1/2 A206: 89-92 WTC 1 206 89-92 Y C-40 c 2 columns, lov\'er 2/3rds A136: 98-101 WTC 1 136 98-101 Y C-46 c__ Nearly 3 full columns B157: 68-71 WTC 2 157 58-71 Y C-48 or S-5 c Nearly 2 full columns ^ B442: 91-94 WTC 2 442 91 - 94 Y C-55 c 1 column, lower 1/3rd 209: 94-97 WTC 1 209 94-97 Y (NSn _ :.....M..:.?r.!../. C-89 c 2 full columns B215: 12 - 15 WTC 2 215 12 - 15 Y C-92 c Partial of single column B13x: 93-96 WTC 2 130 93-96

Y C-93 c Partial of single column 339: 99- 102 WTC 1 339 99 - 102

Y CC c 2 full columns 124: 73-70 WTC 1 124 70-73

iDoes not match K-1 orK-13 c 3 columns, lower 1/3rd 209: 97-100 WTC 1 2tB 97-100 Y K-2 or K-40 c 1 column, lower 2/3rds 236: 92-95 WTC 1 236 92-95

Y M-2 c Full panel -9 <63> WC 1 130 96-99 M-10a c 3 columns, 1/3rd, not labeled but attached to M-lOb B209: 82-85 WTC 2 209 82-85 Y M-lOb c 3 columns, lower 1/2 B206: 83-86 WTC 2 206 83-85 M-20 c 2 columns, lower 1/3rd A121: 99-102 WTC 1 121 99-102 M-26 c 3 full columns A130: 90-93 WTC 1 130 90-93 M-27 c 2 columns, lower 3/4ths A130: 93-96 WTC 1 130 93-96 M-28 c 3 columns, lower 1/4th B345: 9x - Ixx WTC 2 345 98 - 101 M 30 c 2 columns, lower 1/3rd 33 94-97 WTC 1 133 94-97

Y N 1 c 2 full columns 2 8" 82-85 WTC 1 218 82-85 Y (as M-3) N-7 or M-3 c 3 full columns 127- 97-100 WTC 1 127 97-100 Y (as M-7) N-8 or M-7 c Full panel A142- 97-100 WTC 1 142 97-100 Y (as M-8) N-9 or M-8 c Almost full panel, missing lower 1/3rd of 1 column A154: 101-104 WTC 1 154 101-104

1 Y jaS M;;15) N-10 or M-15 c 2 columns, lower 2/3rds _ A1J5: 89-92 WTC 1 115 89-92 Y (as M-13) N-12 or M-13 c 2 full columns i 06: 92-95 WTC 1 206 92-95 Y (as M-14) N-13 or M-14 c 3 columns, lower 1/3rd i A130: 99-102 WTC 1 130 99-102 N-99 or M-16 c Almost full panel, missing lower 1/3rd of 1 column 1 A148: 99-102 WTC 1 148 99-102

N-101 orM-21 c 3 full columns iA133: 100-103 WTC 1 133 100-103

IS-lorEE c 2 columns, lower 1/3rd : A433: 79-82 WTC 1 433 79-82 Y lS-9orC-63 cc

Full panel : A133: 97-100 WTC 1 133 97-100 Y iS:10.o.r.C:lZ 2 columns, lower 1/2 i 224: 92-95 WTC 1 224 92-95 S-14 or C-20 c Full panel I 8218:91-94 WTC 2 218 91-94

Table A-3. List of partially identified exterior panel sections

lln FEMA report? NIST Name Type Brief Description Markings BIdg Colurrin Floors

C-117 c 3 columns, lower 1/3 101-104 NA 101-104

NISTNCSTAR 1-3B, WTC Investigation 65
Appendix A

Table A-4. List of unidentified exterior panel sections.

In FEMA report? NIST Name Type Brief Description Location \ Y C-28B (formerly U-4) CC Corner column, in 2 pieces 205 M-35 cc Corner columm 205

Y AA (formerly U-7)

" c 2 full columns, thick walled PL

Y (NSF) c 1 column, bottom l/'Srd of left column PL

Y BB c Single, thick column 205 J

Y C-TT c 2 columns, upper 2/3rds 205 Y C-iS (formerly U-20) c Partial of single column 205 Y C-16 c 1 column, upper Mdid 205 Y C-16a c Fell off during moving of C-16 205 Y C-28 (formerly U-1) c 1 cclumm of unknown location 205 Y C-32 c 1 column, upper 1/3rd 236 Y C-41 c 1 column, lower 2/3rds 205

_Y C-43 c 1 column, lower 1/2 "205 C-47 c 3 columns, upper 1/2

_ 236 Y C-49 or S-6 c portion of 1 column 236 Y C-51 c 2 columns, upper 1.'2 205

C-52 c 1 column, upper 2j3rds 205 Y C-54 c 1 column, small piece wAh extended outer web 205 Y C-64 c 1 column with a lot missing 205

!"""

"y

c-ez""'

' ~ c

1 column, rest unknown 205 Y C-68 c 1 column, upper 1/2 205 Y C-73 c 1 column, upper 1/2 205 Y C-75 c portion of 1 column and spandrel, rest unknown 236 Y C-77 c 2 columns fromi different panels attached at spandrel, 1/3rd of each 205

i Y (NSF) C-84

' c"" 1 full column, stampings on front face PL

C-102 Partial of single column 205

"

C-133 c 1 column, bottom li'Srd of unknown location 205^

_Y DD c 1 Column, spans 1 floor and has end plates on both ends _ _J205

Y FF c Single, thick column

5r 205

Y K-16 1 full column, thick, looks very corroded PL

K-16a (formerly U-23) Fell off of K-16 while mioving PL

Both are in report but

listed separately

t\A A cir \\A ^ Ul \v\--D 3 columns, upper 2/3rds

M-19 c 2 columns, upper 1/3rd . 205

Y Il3'~ 1 column, upper M2 '236"'"' Y N-4

" "c "

1 columm, miiddle 1/3rd 236 Y N-6 (formerly U-2) c 1 column, length of spandrel, crushed 236 Y (as M-9) N-1 1 or M-9 c 3 columns, upper 2/3rds 105

Y (as C-19) N;N or C-19 1 column, lower 1/2 26'5 ' '"'

Y (as C-50) S-3 or C-50 c 1 column, unknown 1/2 205

U-6 c 3 columns, upper 1/4 236

U-1

5

c Partial of single column 205 _

Y K-10 f Cn Flange coupon received from Gross, July 29, 2002 Lab Y K-11 ^ Cn Flange coupon received from Gross, July 29, 2002 Lab Y K-12 Cn Flange coupon received from Gross, July 29, 2002 Lab Y K-13 Cn Flange coupon received from Gross, July 29, 2002 Lab Y Cn Flange coupon received from Gross, July 29, 2002 Lab "

Y K-15 Cn Flange coupon received from Gross, July 29, 2002 Lab Y K-18 t Cn Flange coupon received fromi Gross, July 29, 2002 La'b Y K-19a Cn Flange coupon received from Gross, July 29, 2002 Lab Y K-19b Cn Flange coupon received fromi Gross, July 29, 2002 Lab

B-5004 BT BoviTtie section

' JFK/PL

B-5007 bt"""" Bovilie section JFK/PL

66 NISTNCSTAR 1-3B. WTC Investigation
Data on Recovered WTC Steel

Table A-5. List of identified core columns.

In FEtalA report? NIST Name Ikes RBBrief Description Markings Eldg plpors

B-101

1

HG3vy fGctsn^ulsf column OUOM *^j_tv V'/TC 1 MO 51-54

B-6 152-1 RB Hsavy fectdriQulsr column fin? A 1C, IP, ,-C9> WTC 1 OUJ 15-18 B-6152-2 RB Heavy rectangular column 504A: 33-36 WTC1 504 _ 33-36

- - NSF C-83 RB

Heavy r&ctanQular column FEMA reported as

possible core column No ID found, but similar to core column size and shape

C-88a RB

Hiiilt-iin Knv i^nliimn FFh^A rannriaA nncc'iMa r-nra uuiii'Ufj UUA LUiUFiiri, r civiM FcpuileU pUsolDIc LDic column 801 B 80-83 WTC 2 801 80-83

C-88b Similar shape welded to above column 801 B 77-80 WTC 2

801

"

77-80 NSF C-90 RB

Hp3vu rprtnnniilnr rnliimri FPMA rpnnrtoH ac

possible core column 701B 12-15 wrc2 701 12-15 .

,

C-30 or S-12 W Wide flange 1008B x04-10)( 'WTC2^ 1008 104 - 106

C-65 or S-8 W Wide flange 904A (86-89) <52> WTC 1 904 Y C-71 W Wide flange 904A 77-80 WTC 1 904 77 - 80

C-80 W Wide flange, FEMA reported possible core columns 603A 92-95 <_51>^ W7C 1 603 92-95

C-155 (formerly U-5) W Wide flange 904A 83-86 wrci 904 83-86

HH or S-2 W Wide flange, FEMA reported possible core columns 605A 98-101 wrc 1 " SB

" »ior

Table A-6. List of built-up box beams and wide flange sections with

ambiguous stampings.

NIST Name Type Brief Description Markinas Location

Markinqs but no knowledge of this coding i C-79 RB Rectangular column, FEMA reported possible core column 101 A 81 -85-87-92 52 1 PL

C-101 (fotmerly U-16) RB Similar to corner column, but much thinner 78A 10 27 50 PL

C-154 RB Thin rectangular beam with supports 825 107-108 52 PL

.C-2B ^ _ _W Three connected Wide flanges 504 &605 (107) <B4> FySd PL

C-44 W Wide flange, FEMA reported possible core columns 59 S 563 PL

C-45 W Wide flange, FEM.A reported possible core columms 16 S2 563 Fy50 PL

'c-60 W Wide flange, S-shaped 193 SI 57 PL

C-61 W Wide flange

^ 150 S 69 PL

C-62 W Wide flange 224 (S)<48> Fy50 PL

M-17 W Wide flange or I-beam, 1ft flange, 2 ft web, 50-60 ft long 163 (9) 62 Fy36 205

.M-23 W Possiblypart of Wid e_fl a ii g e or 1- beam F2010 PL

;iVl-37 W Wide flange 130 (8?-92) <50> j 205

IVl-38 W Wide flange _„J PL

NISTNCSTAR 1-3B, WTC Investigation 67
Appendix A

Table A-7. Ust ofjjnidentified wide flange sections.

In FEMA report? NIST Name Type Brief Description Location

B-1022 W

W

Thick wide flange with severe bend 205

B-1075 Wide flange 205

Y C-29 (formerly U-10) w Wide flange 205

Y C-35 w Wide flange 205 _ _Y C-69 w Wide flange 205

Y C-70 (formerly U-9) \V Wide flange 205

Y C-72b w Wide flange 205

Y C-76 w Wide flange 205

Y C-78 (formerly U-8) w W\6e flange 205 Y C-81 w Wide flange 205 Y C-82 w Wide flange 205 Y (NSF) C;85 w Wide flange 205 Y C-87 w Thick Wide flange 205

C-123 w Small Wide flange 205

C-126 w Wide flange 205

C-130 w V%'ide flange 205

C-138 w V'v'ide flange 205

C-142 w Wide flange 205

C-150 M Wide flange 205

Y M-11 w Wide flange 205

M-18 RB Large box beam 205

M-22 RB Large box beam 205

M-33 W Wide flange 205

SM-2 W Wide flange 205

Y W-14A or A W Heavy Wide flange 1 205

Y W-14B W Heavy Wide flange ( PL

68 NISTNCSTAR 1-3B. WTC Investigation
Data on Recovered WTC Steel

Table A-8. List of recovered floor truss material.

In FEMA report? NISI Name Type Brief Description Location Y C-53 J Floor truss PL

Y C-53B J Floor truss PL

C-100 J Possible angle from a floor truss PL

C-104 J Possible angle fronri a floor truss PL

C-106 (formerly U-18) J Small piece of floor truss 202

C-115 J Pig-tailed piece from floor truss Lab

J Piece of floor truss PL

C-131 J Small portion of floor truss with cement 202

j C-132 J Piece of floor truss PL ! C-137a J Piece of floor truss PL

C l^^b J Piece of floor truss PL

C-137C J Piece of floor truss PL

rc-137d J Piece of floor truss PL

C-137f J Piece of floor truss PL

C-140 J Piece of angle PL

C-14Bb J Piece of floor truss PL

C-149 J Piece of floor truss PL

C-151 J Piece of floor truss PL

M-25 J Small piece of floor truss 202

M-31 J Pieces of floor truss Lab M-32 J Pieces of floor truss Lab M-36 J Thick angle from floor truss PL

- Y (as N-2) T-1 or N-2 J Floor truss 202

Table A-9. List of recovered channel material.

In FEMA report? NIST Name Type Brief Description Location

Y C-91 Ch IChannel 236

C-95 Ch Channel 236

C-96 Ch Channel 236

C-97 Ch Channel 236

C-98 Ch Channel 236

C-99 Ch Channel 236

C-105 Ch Channel 236

C-107 (formerly U-19) Ch Channel 236

C-118 Ch Channel 236

C-124 Ch Channel 236

C-125 Ch Channel ^ 236

C-128 Ch Channel B

C-129 Ch Channel 236

C-134 Ch Channel 236

C-139 Ch Channel 236

C-141 Ch Channel 236

C-143 Ch Channel 236

C-144 Ch Channel 236

C-145 Ch Channel 236

C-147 Ch Channel 236

C-148 Ch Channel 236

C-152 Ch Channel 236

C-153 Ch Channel 236

M-24 Ch Channel 236

M-34 Ch Channel B

NISTNCSTAR 1-3B, WTC Investigation 69
Appendix A

Table A-10. List of material from WTC 5.

In FEMA report? NIST Name Brief Description Location \ Cn5 Coupon from BIdg ffi Lab i \GZ2 Cn5 Coupon from BIdg ffi \gZ3 ' Cn5 Coupon from BIdg #5 Lab ! \GIr4 Cn5 Coupon frorri BIdg #5 Lab i

\ iGZ;S_ Cn5 Coupon from BIdg i& Lab i Cn5 Coupon fromi BIdg #5 Lab !

! ' \GZ7 1 Cn5 Coupon from BIdg #5 Lab 1

Table A-11. 1-ist of miscellaneous material.

In FEMA report? NIST Name Type

B

Brief Description Location

i C-18 Associated Une washet and nut Lab

i C-108 B Three sheared bolts Lab

C-109 B Single bolt sheared Lab

C-110 Bolt and nut Lab~' "

C-111 B Bolt and washer "Tab

C-112 B Single bolt sheared Lab

C-113 B Tvifo sheared bolts with washers Lab

C-114 B Sheared bolt with nut Tab

M-26 associated 8 bolts and a nut

, Lab

CJJJ^22 H Damper Lab

B- 1044-1 0 Piece of crushed metal decking assoc with B-1044 202

B-2150 0 Pieces of aluminum sheathing 202

C88c (formerly U-22) 0 Broke off C-88 PL

C-94 0 Ivtay be some type of brace, rectangular box construction PL

C-103 0 Square-tube construction PL

C-119A 0 Square-tube construction PL

C-119B 0 Square-tube construction PL

C-12D 0 Square-tube construction PL

C-121 0 Square-tube construction PL

C-135 0 tvlay be some type of brace, rectangular box construction PL

C-146 6 Mangled ball of steel and concrete 202

C-156 (formerly U-17) ^

p I Square-tube construction PL

Y K-50a Rectangular slab of steel with bolts, received from D. Sharp, SEAoNY Lab Y K-50b 0 Rectangular slab of steel with bolts, received from D. Sharp, SEAoNY Lab

r " y" K-50c gRectangular slab of steel with bolts, received from D. Sharp, SEAoNY Lab ' "

M-17a (formerly U-24) 0 Fell off of M-17 while moving 202

M-29 ~

5 ft piece of strapping 202

M-30 associated 6

Pieces of glass, plexiglass, other rubble Ljb

Y l\l-5 0 Plate vv'ith bolts PL 1

U-25 0 Unknown Wide flange with concrete 205

70 NISTNCSTAR 1-3B, WTC Investigation
Data on Recovered WTC Steel

A.2 REPRESENTATIVE PICTURES OF RECOVERED WTC STEEL

NISTNCSTAR 1-3B, WTC Investigation 71
Appendix A

Source: NIST. Figure A-1. Exterior column panel, sample C-46 shown.

72 NIST NCSTAR 1-3B, WTC Investigation
Data on Recovered WTC Steel

Source: NIST. Figure A-2. Floor truss seats shown from sample N-8.

NISTNCSTAR 1-3B, WTC Investigation 73
Appendix A

Seat

Damping unit with missing viscoelastic

material. Damping unit has been bent into an

upright position.

Gusset plate for viscoelastic damping unit attachment to column interior.

Figure A-3. Damping Unit shown from sample N-8.

Welded gusset plate used in place of seat on

alternate column/spandrel intersections. One

method used to attach diagonal bracing strap to exterior wall

Source: NIST. Figure A-4. Gusset plate shown from sample N-8.

74 NIST NCSTAR 1-3B, WTC Investigation
Data on Recovered WTC Steel

Sample M-29

Source: NIST.Figure A-5. Diagonal bracing strap shown on sample C-25 (top), and

single strap labeled M-29 (bottom).

NISTNCSTAR 1-3B, WTC Investigation 75
Appendix A

B-5004 portion cut and moved to NIST campus

Source: NIST. Figure A-6. Bowtie section of exterior wall.

76 NIST NCSTAR 1-3B, WTC Investigation
Data on Recovered WTC Steel

Samples C-83 and C-90

Source: NIST. Figure A-7. Recovered rectangular built up box sections used as core columns.

NISTNCSTAR 1-3B, WTC Investigation 77
Appendix A

Source: NIST. Figure A-8. Recovered wide flange sections used as core columns.

78 NISTNCSTAR 1-3B, WTC Investigation
Data on Recovered WTC Steel
Appendix A

Source: NIST. Figure A-10. Recovered floor truss material; shown are portions of sample C-53.

80 NISTNCSTAR 1-3B, WTC Investigation
Data on Recovered WTC Steel

Source: NIST. Figure A-1 1 . Recovered inner channel material used to connect floor trusses to core columns; shown is sample C-129.

Source: NIST. Figure A-12. Coupons removed in the field from WTC 5; shown is sample GZ-1.

NISTNCSTAR 1-3B. WTC Investigation 81
Appendix A

Source: NIST. Figure A-13. Examples of recovered bolts from various samples.

82 NISTNCSTAR 1-3B, WTC Investigation
Data on Recovered WTC Steel

Source: NIST. Figure A-14. Examples of miscellaneous materials recovered.

NISTNCSTAR 1-3B, WTC Investigation 83
Appendix A

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84 NISTNCSTAR 1-3B, WTC Investigation