NIST NCSTAR 1-11

Federal Building and Fire Safety Investigation of the

World Trade Center Disaster

Post-Construction Modifications to

Fire Protection, Life Safety, and

Structural Systems of

World Trade Center 7

Raymond A. Grill Duane A. Johnson

David A. Fanella

National Institute of Standards and Technology • Technology AdministroJion • U.S. Departmeni of Commerce

NIST NCSTAR 1-11

Federal Building and Fire Safety Investigation of the

World Trade Center Disaster

Post-Construction Modifications to

Fire Protection, Life Safety, and

Structural Systems of

World Trade Center 7

Raymond A. Grill Duane A. Johnson

David A. Fanella

Rolf Jensen & Associates, Inc.

September 2005

U.S. Department of Commerce

Carlos M. Gutierrez, Secretary

Technology Administration Michelle 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 tine 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 1-11 Natl. Inst. Stand. Technol. Natl. Constr. Sfty. Tm. Act Rpt. 1-11, 46 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

This report was prepared to support the analysis of building and fire codes and standards of the National

Institute of Standards and Technology World Trade Center (WTC) Investigation. This report was

prepared to support the overall objective of detennining how and why WTC 7 collapsed. The purpose of

this report is to document modifications and/or repairs of the fire protection, life safety, and structural framing systems of WTC 7.

Keywords: Beams, building modifications, cover plates, fire alarm, fire protection, fire safety, fire sprinklers, floor slab openings, high-rise buildings, life safety, means of egress, pressurization, structural framing, tenant alterations, voice communication, web openings, wide-flange T-sections, World Trade

Center.

NISTNCSTAR 1-11, WTC Investigation iii
Abstract

This page intentionally left blank.

iv NISTNCSTAR 1-11, WTC Investigation
Table of Contents

Abstract iii

List of Figures vii

List of Tables ix

List of Acronyms and Abbreviations xi

Glossary xiii

Preface xv

Executive Summary xxv

Chapter 1 Introduction 1

1 . 1 Fire Protection and Life Safety 1

1 .2 Structural Framing 2

1.3 References 2

Chapter 2 Modifications to Fire Protection and Life Safety Systems 3

Chapter 3 Structural Modifications due to Tenant Alterations 11

Chapter 4

Openings Made in Floor Slabs 1

5

4.1 Description of the Modifications 15

4.2 References 16

Chapter 5 Modifications Made to Beam Webs and Flanges 17

NISTNCSTAR 1-11, WTC Investigation v
Table of Contents

This page intentionally left blank.

vi NISTNCSTAR 1-11, WTC Investigation
List OF Figures

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

disaster xvii

NISTNCSTAR 1-11, WTC Investigation vii
List of Figures

This page intentionally left blank.

vni NISTNCSTAR 1-11, WTC Investigation
List of Tables

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

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

Table 2-1. Summary of modifications to WTC 7 fire protection and life safety systems 3

Table 3-1. Modifications made due to tenant alterations 1

1

Table 4-1 . Openings made in floor slabs 1

5

Table 5-1. Modifications made to beam webs and flanges 17

NISTNCSTAR 1-11, WTC Investigation ix
V I

This page intentionally left blank.

NISTNCSTAR 1-11, WTC Investigation
List of Acronyms and Abbreviations

Acronyms

AblM A5s 1 M international

Building Code of the City of New York (Local Law No. 76)

HVAC heating, ventilating, and air conditioning

NFPA National Fire Protection Association

NIST National Institute of Standards and Technology

PANYNJ Port Authority of New York and New Jersey

WTC 1 World Trade Center 1 (North Tower)

WTC2 World Trade Center 2 (South Tower)

WTC 7 World Trade Center 7

Abbreviations

ft foot

in. inch

WTl 5x74 American Institute of Steel Construction/ASTM standard abbreviation for a box (tube)

beam of cross section 15 in. by 74 in. WT24x55 American Institute of Steel Construction/ASTM standard abbreviation for a wide flange

beam of cross section 24 in. flange and 55 in. web.

NISTNCSTAR 1-11, WTC Investigation xi
List of Acronyms and Abbreviations

1

This page intentionally left blank.

Xll NISTNCSTAR 1-11, WTC Investigation
Glossary

active fire protection - A means to help prevent the loss of life and property from fire by extinguishing,

suppressing, or controlling a fire through functional systems. Sprinkler systems, fire alarm systems, and

smoke control systems are examples of active fire protection.

area of refuge - A floor area to which egress is made through a horizontal exit or supplemental vertical

exit.

combustible - A material that is not determined to be noncombustible.

damper - A device installed in heating, ventilating, and air conditioning ductwork used to prevent the spread of fire and/or smoke. Dampers are provided to maintain a fire resistance rating of the assembly

being penetrated.

detector - An initiation device that automatically detects a change in state, such as presence of smoke,

high temperature, or abnomial rate of temperature rise.

fire alarm system - A system, automatic or manual, arranged to give a signal indicating a fire emergency

and initiate the appropriate response.

fire resistance rating - The time in hours that materials or their assemblies will withstand fire exposure

as determined by a fire test.

fireproofing - Materials or assemblies used to provide a fire resistance rating to a building component.

firestop - A solid or compact, tight closure to retard the spread of flames or hot gases within concealed

spaces.

initiation device - A system component that originates a change-in-state signal in the fire alarm system.

An initiation device begins the life safety processes, such as evacuation; heating, ventilating, and air conditioning shut down; elevator recall, etc.

manual fire alarm box - A manually operated initiation device that originates a change-in-state signal in the fire alarni system.

means of egress - A continuous and unobstructed path of vertical and horizontal travel from any point in a building to a public way. The means of egress consist of the exit access, the exit, and the exit discharge.

noncombustible - A material that, in the fonn in which it is used in construction, will not ignite and bum

when subjected to fire. However, any material which liberates flammable gas when heated to any

temperature up to 1,380 T for 5 min shall not be considered noncombustible.

notification appliance - A fire alarm system component such as a bell, horn, speaker, or strobe that provides audible, tactile, or visible outputs, or any combination thereof

NISTNCSTAR 1-11, WTC Investigation xiii
Glossary

passive fire protection - Fire protection features that are incoiporated into the building construction or building materials that do not rely on active fire protection methods to limit fire ignition, fire growth, or material failure. Fire separations and divisions, sprayed-on fire proofing, and enclosing structural members with noncombustible materials are examples of passive fire protection.

smoke and heat venting - A process used to move products of combustion to the outdoor air.

xiv NISTNCSTAR 1-11, 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 performance 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 detemiine 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. Detemiine 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 1-11, WTC Investigation XV
Preface

NIST is a nonregulatoiy 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

perfonnance and emergency response and evacuation procedures in the wake of any building failure that has resulted 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 puipose of each project is summarized

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

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 Performance and

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

Analyze the baseline performance of WTC 1 and WTC 2 under

design, service, and abnormal 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

Determine 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 performance 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

Environment; 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 terrorist attacks on WTC 1 and WTC 2 until the collapse of

WTC 7, including practices followed and technologies used.

xvi NISTNCSTAR 1-11, WTC Investigation
Preface

NIST WTC Investigation Projects

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

Safet>' 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 DiNermo, President, Hughes Associates, Inc.

NISTNCSTAR 1-11. WTC Investigation xvii
Preface

• Robert Hanson, Professor Emeritus, University of Michigan

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

Inc.

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

University of Colorado at Boulder

• Fonnan 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 recommendations,

however, are solely the responsibihty 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 ten-orist 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.

XVlll NISTNCSTAR 1-11, WTC Investigation
Preface

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

Date Location Principal Agenda

lune ~>4 "'00"' New Ynrk Titv NY I UUllL IllCCllilii,. 1 UUllC LUIIllilClJlS Ui) lilC LJiUfi I lUrl lUl lilC pending WTC Investigation.

VJal UiCI oUUI U, IVIL/ IViCUia UllCllIll^ allllUUIlLlll^ IIIC lUIlIldl Mall UJ lllc HI VCSUgallUIl.

Deremher Q

"'00''

v> aoi ill 1 ^ivjj 1, LW_ JVlCUlU UllCIIli^ KJll IClCaoC Ul UlC / UiJlIC LJIJUUtt. dllU INIOI ICCJUC^l for photographs and videos.

Anril 8 "'00^ Klpw iNcw Ynrl- I ui K Pitv v_iiy, MYi> I juiiii puuiic lui ujii Willi \_uiuiiiuia uiiivcisiiy uii 1 11 ai-pci dUII interviews. Apni zy—ju, zuuj Gaithersburg, MD NCST Advisory Committee meeting on plan for and progress on WTC Investigation with a public comment session. Mq^' IVldv 7/, .-UUj Tin^ KIcm; i\ew V(^rl' 1 orK Pih; ciiv . W]> 1 Media briefing on release of A/i/v 2003 Progress 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 fi-om 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 01 preliminary iindings 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 1 ork 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 disposifion 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 regulator}' authorities

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

NISTNCSTAR 1-11. WTC Investigation XIX
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. NISTNCSTARIA. 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 I-IA. 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 ofthe 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 1-1 D. 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 ofCodes, 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 ofthe 1968 and Current (2003) New

XX NIST NCSTAR 1-11, 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 ofthe World

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

York Cit)> Building Code by Local Laws Adopted While World Trade Center J, 2, and 7 Were in Use. NIST NCSTAR 1-lG. Nationallnstitute 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: Post-Construction Modifications to Fire Protection and Life Safety Systems

of World Trade Center 1 and 2. NIST NCSTAR I-IH. 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

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

Safety, and Structural Systems of World Trade Center 7. NIST NCSTAR 1-1 1. 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 Safet}' Investigation ofthe World Trade Center Disaster: Reference Structural Models and Baseline Performance Analysis of

the World Trade Center ToM'ers. 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 of the World Trade

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

NCSTAR 1-2B. 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 PubHcation 1-3 A. National Institute of Standards and Technology.

Gaithersburg, MD, September.

NIST NCSTAR 1-11, WTC Investigation xxi
Preface

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

Disaster: Steel Inventory 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 ofthe 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 of the 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 of the 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.

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

Investigation of the World Trade Center Disaster: Post-Construction Fires Prior to September 11,

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 Syste?iis. 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 of the 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.

xxii NIST NCSTAR 1-11, WTC Investigation
Preface

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

J. Yang, G. Mulholland, K. R. Prasad, S. Kukuck, R. Anleitner 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 Institute of

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 of the 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 1-11, WTC Investigation xxni
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. Nationallnstitute 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. Nationallnstitute of Standards and Technology.

Gaithersburg, MD.

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

Disaster: Analysis ofSeptember 1 1 , 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 of the 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 ofthe 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 Safet)' 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 of the World Trade Center

Disaster: Technical Documentationfor Swvey Administration. NIST NCSTAR I-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.

XXIV NIST NCSTAR 1-11, WTC Investigation
Executive Summary

The purpose of this report is to identify the repairs and/or modifications made to the fire protection, life safety, and structural framing systems of World Trade Center (WTC) 7 from initial occupancy to September 11, 2001. Documentation for more than 120 tenant alterations to WTC 7 was located and

reviewed. Fire protection, life safety, and structural framing systems for these alterations are summarized

in this report.

The fire protection and life safety systems were modified to accommodate new tenant layouts. As walls were removed, added, and relocated, the requirements for the fire protection and life safety systems

changed. As wall layouts were modified, fire sprinkler and fire alarm devices were relocated. Fire and

smoke dampers were installed as required by the Building Code of the City of New York (BCNYC). Life

safety requirements of the BCNYC, such as travel distance requirements, were analyzed. A list is provided of the tenant alterations that modified the fire protection and life safety systems.

Most of the structural modifications were done to accommodate tenant requirements. Horizontal

members of the floor framing system were strengthened due to increased loading from high-density files. Strengthening of these beams and girders was achieved by welding cover plates to the bottom flanges, the underside of the top flanges, or both. In some cases, new beams were introduced to carry a portion of the new load.

Floor slabs were completely removed on the east side of the building to accommodate trading floors for Salomon Brothers, Inc., but were subsequently replaced when the trading floors were moved to another

location. Columns in this area, which had twice the unsupported length after the slab removal, were

reinforced. Other openings were cut into a few floor levels to accommodate new stairways connecting

adjoining floors.

Web openings were cut through some beams and girders to allow passage of ductility work. ]n some

cases, the beams or girders had to be reinforced in order to increase capacity.

NISTNCSTAR 1-11, WTC Investigation XXV
Executive Summary

This page intentionally left blank.

XXVI NISTNCSTAR 1-11, WTC Investigation
Chapter 1 Introduction

Over the life of World Trade Center (WTC) 7, enhancements to the fire protection, life safety, and

structural framing systems were made. Tenant alterations, fires, revised building code provisions, and new technology all were the reasons for the enhancements of the systems. Changes made to these systems ultimately affected the building performance. Thus, in order to analyze the performance of

WTC 7 in response to the attacks of September 1 1

, 2001 , it is crucial to have the most current configuration of the systems installed. The purpose of this report is to identify the repairs and/or

modifications made to the fire protection, life safety, and structural framing systems of WTC 7 from

initial occupancy to September 11, 2001.

1.1 FIRE PROTECTION AND LIFE SAFETY

Tenant alteration projects included modifications of the fire protection and life safety systems within

WTC 7. Tenant spaces were modified to accommodate new floor layouts as tenants moved in and out. New wall layouts, changed occupancy use, and mission continuity objectives in tenant spaces introduced

different code requirements.

Tenant alterations performed in WTC 7 included typical business occupancy modifications to the fire protection and life safety systems. A typical office alteration included rearranging walls to accommodate

the desired layout of the tenant while maintaining proper fire separations and divisions from other tenants within the building. Fire and smoke dampers were installed in the heating, ventilating, and air conditioning systems where penetrations of fire rated walls occurred. The base building wet pipe

sprinkler system was modified by the addition and/or relocation of sprinkler heads and branchlines in the tenant space as called for in National Fire Protection Association (NFPA) 13 and the Building Code of the City of New York (BCNYC) requirements for minimum spacing from these walls. Hydraulic

calculations were performed to justify the pipe sizes of the branch lines as necessary. Documentation

indicates that calculations were conducted back to the floor control valve assembly of each floor where

system pressures were previously known. Fire alarm and voice communication systems were installed in accordance with NFPA 72 and the BCNYC requirements within each tenant space, again to maintain

minimum spacing from relocated walls. Although documentation does not exist for each project, an

egress analysis was generally performed to verify that travel distances and other means of egress requirements in the BCNYC were not exceeded. Providing exit and emergency lighting within the tenant

space, which was required by the BCNYC, was also included in the tenant alteration project. The system

modifications were submitted to the Port Authority of New York and New Jersey (PANYNJ or Port Authority) for approval or were approved using the self-certification process established by the PANYNJ.

Tenant Construction Review Manuals, provided by the PANYNJ Engineering Department, were used for establishing minimum design criteria and design details.

Whenever work was done in the WTC buildings, a project number was assigned by the Port Authority

under which all contracts, drawings, and correspondence was filed. These numbers are typically of the format W(yy)-1234 (where yy is the year initiated and 1234 is a four-digit number). This report includes

NISTNCSTAR 1-11. WTC Investigation 1
Chapter 1

these numbers as references to individual projects, and files retained by the Port Authority are identified by these numbers.

Most of the structural modifications were done to accommodate tenant requirements. These generally

involved strengthening the horizontal members of the floor framing system due to increased loading from

high-density files (see Table 3-1 in Chapter 3). Strengthening of the beams and girders was achieved by

welding cover plates to the bottom flanges and/or to the underside of the top flanges. In some cases, deficiencies were remedied by introducing a new beam between existing beams to reduce the tributary

load on the deficient beams. In other cases, wide-flange T-sections were welded directly to the underside

of deficient girders.

Floor slabs were completely removed on the east side of the building to accommodate the trading floors for Salomon Brothers, Inc., but were subsequently replaced when the trading floors were moved to another location (Cantor 1989). The only framing members that remained on these floors from the

original design were the columns and the girders that were part of the lateral-force-resisting system. The

columns, which had twice the unsupported length after the slab removal, were reinforced in this area. Other openings were cut into a few floors to accommodate new stairways connecting adjoining floors. New framing members were introduced where needed.

Web openings were cut through some beams and girders to allow passage of utility ductwork. These

openings were typically reinforced with plates. In some cases, an inverted T-section was welded to the bottom flange of the existing beam to increase the capacity of the beam in the area of the opening.

Shallow notches were cut in the top and bottom flanges of some of the beams to accommodate ductwork.

To make up for lost capacity, plates were introduced just under the top flanges and just above the bottom

flanges.

Other minor modifications were made, including the installation of supports for folding partitions.

The remainder of this report identifies the specific major modifications and repairs that were made to the

fire protection, life safety, and structural framing systems of WTC 7.

Cantor (The Office of Irwin G. Cantor P.C.). 1989. "Salomon Brothers, Inc., Base Building

Modifications - 7 World Trade Center Structural Computations." W-7004, Port Authority. Newark,

1.2 STRUCTURAL FRAMING

1.3 REFERENCES

January.

2 NISTNCSTAR 1-11, WTC Investigation
Chapter 2

Modifications to Fire Protection and Life Safety Systems

The fire protection and life safety modifications of World Trade Center (WTC) 7 are listed in Tabic 2-1

.

Most of the tenant alterations followed the typical business occupancy modification summary previously

identified in Chapter 1 of this report. Tenant alterations with additional modifications or modifications

that varied from the typical modification summary of Chapter 1 are noted in the last column of Table 2-1.

The year and floor location of the alteration are also given to provide a history of the floor or portion

thereof Tenant alteration documentation was not located for all floors, and thus, not every floor is identified in Table 2-1

.

Table 2-1. Summary of modifications to WTC 7 fire protect on and life safety systems.

TAA No. Floor(s)

Location on Floor Year Tenant Systems Modified

W98-1734 1 Core 1998 Office of Emergency

Management

Typical, including Inergen system

for fuel tanks

W-7005 2,4 Northeast 1989 Salomon Brothers, Inc. Typical

WOO-7108 3 Core 2000 Salomon Smith Barney Typical

W-8006 3 Southeast 1990 Tobacco Shop Typical

W95-7140 3 Northeast 1995 Salomon Brothers, Inc. Typical

W98-7195 3 Lobby 1998 WTC 7 Egress analysis

WOO-7004 4, 29-37,

39^4,

47

Various 2002 Salomon Smith Barney Various modifications, mostly

utilities and structural but includes new halon system (34th floor)

W95-7109 7 Entire 1995 American Express Bank Typical

W98-1734 7 South 1998 Office of Emergency

Management

Removal of sprinklers from

generator room

W98-7230 7 Core 1999 Silverstein Properties Typical

W99-7175 7 Northeast 1999 American Express Typical

NISTNCSTAR 1-11, WTC Investigation 3
Chapter 2

Table 2-1. Summary of modifications to WTC 7 fire protection

and life safety systems (continued).

TAA No. Floor(s)

Location on Floor Year Tenant Systems Modified

W93-7233 7, 8 Entire 1994 American Express Typical

WOl-7131 7, 8, 13 Northwest 2001 Unknown Typical

WOO-7143 8 Northwest 2000 American Express Typical

W94-7187 8 West 1995 American Express Bank

Check Processing

Department

Typical

W94-

7176.02

9, 10 Entire 1994 Ambassador Construction

Project

Typical

W-8005 10-12 Various 1990 Spicer and Oppenheimer Typical

W92-7056 11, 12 Entire 1992 Securities Exchange

Commission

Typical

WOO-7185 13 Southeast 2000 Standard Chartered Typical

W92-7056 13 North 1992 Securities Exchange

Commission

Typical

W97-7202 13 Northeast 1997 Salomon Brothers, Inc. Typical

WQQ-71 '',1 vv yy 1 I J 11 ^ Mr\t*f iNUI rli^Q ct lliCac>l 1 yyy 1 y piLal

vv yKj / 1 o_>

,

W97-7150

1 H— 1 U V ai iUUa 1 yy\j,

1997

lIlMilallCC OCIVILCc* V^IIILC

w-8nn4 vv OV/U't^, W-8013,

W95-7110

14—17 1 H 1 / Entire 1 Qon

1993,

1995

1 y UlCal

W-7002 15 Southeast 1988 Cameron and Colby Typical

W-8004 18 Southwest 1990 Insurance Services Office Typical

W-8009 18 Core 1991 Silverstein Typical

W92-7150 18 Northeast 1992 Equal Employment

Opportunity Commission

Typical

4 NISTNCSTAR 1-11, WTC Investigation
Modifications to Fire Protection and Life Safety Systems

Table 2-1. Summary of modifications to WTC 7 fire protection

and life safety systems (continued

TAA No. Floor(s)

Location on Floor Year Tenant

'

1 Systems Modified

W96-7189 18 South 1996 Insurance Services Office Typical

W98-7203 18 West 1998 ISO 2 Typical

W-8010 19 East 1991 Hartford Insurance Group Typical

W96-7118 19 West 1996 National Association of

Insurance Commissioners

Typical

W97-7101 19 North 1997 ITT Hartford Typical

W95-7153 20 Entire 1995 Hartford Insurance Group Typical

W-8010 20,21 Entire 1991 Hartford Insurance Group Typical

W95-7179,

W95-7205

21 East 1995,

1995 ITT Hartford Typical

W96-7150 21 Southwest 1996 ITT Hartford Typical

W97-7129 21 West 1997 Salomon Brothers, Inc. Typical

W97-7135 21 Core 1997 ITT Hartford Typical

W94-7107 22 Entire 1994 Federal Home Bank of

New York

Typical, including new pre-action

system

W98-7109 22 Southwest 1998 Federal Home Loan Bank

of New York

Typical

W98-1734 23 Entire 1998 Office of Emergency

Management

Typical, including new pre-action

system

W-8003 24, 25 Entire 1 989 Opnartmpnt nf Trp^Qiirv —

IRS

Typical

W95-7163 26, 27 Entire 1995 Standard Chartered Typical

W93-7160,

W93-7138,

W93-7246

28 Entire 1993 Salomon Brothers, Inc. Typical

W94-7180 28 Northeast 1994 Salomon Brothers, Inc. Typical

NISTNCSTAR 1-11, WTC Investigation
Chapter 2

Table 2-1. Summary of modifications to WTC 7 fire protection

and life safety systems (continued).

TAA No. Floor(s)

Location on Floor Year Tenant Systems Modified

W96-7185 28 Various 1996 Salomon Brothers, Inc. Typical

W97-7173,

W97-7186

28 Various 1997,

1997

Salomon Brothers, Inc. Typical

W99-7168 28-32,

34

Core 1999 Salomon Smith Barney Typical

WOO-7194 29 Southeast 2000 Hartford Insurance Typical

W93-7148 29 Entire 1993 Salomon Brothers, Inc. Typical

W97-7]72 29 East 1997 Salomon Brothers, Inc. Typical

WOO-7122 30 Core 2000 Salomon Smith Barney Typical, including new pre-action

system

W94-7141 30 East 1994 Salomon Brothers, Inc. Typical

W94-7207 30 East 1994 Salomon Brothers, Inc. Typical

W97-7132 30 Southeast 1997 Salomon Brothers, Inc. Typical

W97-7152 30 Southeast 1997 Department of Defense Typical

WOO-7127 31 Core 2000 Salomon Smith Barney Typical, including new pre-action

system

WOO-7128 32 Core 2000 Salomon Smith Barney Typical, including new pre-action

system

WOO-7225 32 Entire 2000 Salomon Smith Barney Typical

W93-7155 33 Southwest 1993 Salomon Brothers, Inc. Typical

W93-7212 33 South 1994 Salomon Brothers, Inc. Typical

W99-7160 33 Southwest

& Core

1999 Salomon Smith Barney Typical

W99-7161 33 Core 1999 Salomon Smith Barney Typical, including new pre-action

systems

6 NISTNCSTAR 1-11, WTC Investigation
Modifications to Fire Protection and Life Safety Systems

Table 2-1. Summary of modifications to WTC 7 fire protection

and life safety systems (continued).

TAA No. Floor(s)

1 .nrstion on Floor Year Tenant Systems Modified

W93-7137,

W93-7157,

W93-7207,

W93-7237,

W94-7134,

W94-7230

34 Entire 1993,

1993,

1993,

1993,

1994,

1994

Salomon Brothers, Inc. Typical

W97-7119 34 South 1997 Salomon Brothers, Inc. Typical

W93-7151 35 Southeast 1993 Salomon Brothers, Inc. Typical

W93-7231 35 Southeast 1994 Salomon Brothers, Inc. Typical

W94-7195 35 Southwest 1994 Salomon Brothers, Inc. Typical

W-7005 35,44 Entire 1989 Salomon Brothers, Inc. Typical, including egress analysis

for assembly space

WOO-7139 36 East 2000 Salomon Smith Barney Typical

W96-7196 36 Various 1996 Salomon Brothers, Inc. Typical

W99-7122 36 Northeast 1999 Salomon Smith Barney Typical

W99-7I44 36, 39 Core 1999 Salomon Smith Barney Typical, including new pre-action

systems

W99-7148 36-43 Core 1999 Salomon Smith Barney Typical, including new pre-action

systems

WOO-7188 37 Entire 2000 Salomon Smith Barney Typical

W99-7134 37 Entire 1999 Salomon Smith Barney Typical

WOO-7224 38 Northeast 2000 Salomon Smith Barney Typical

W94-7102 38 Entire 1994 Salomon Brothers, Inc. Typical

W96-7179 38 North 1996 Salomon Brothers, Inc. Typical

W97-7167 38 Northeast 1997 Salomon Brothers, Inc. Typical

NISTNCSTAR 1-11, WTC Investigation 7
Chapter 2

Table 2-1. Summary of modifications to WTC 7 fire protection

and life safety systems (continuec )

TAA No. Floor(s)

Location on Floor Year Tenant Systems Modified

WOO-7202 39 Entire 2000 Salomon Smith Barney Typical

W93-7102 39 Entire 1993 Salomon Brothers, Inc. Typical, includes egress analysis

for auditorium

W95-7173 39 Core 1995 Salomon Brothers, Inc. Typical

W96-7120 39 Northeast 1996 Salomon Brothers, Inc. Typical

W97-7138 39 Northeast 1997 Salomon Brothers Inc. Typical

W99-7119 39 Northeast 1999 Salomon Smith Barney Typical

W99-7127 39^6 East 1999 Salomon Smith Barney Typical

W99-7172 40 Entire 1999 Salomon Smith Barney Typical

W93-7118 41 Northwest 1993 Salomon Brothers, Inc. Typical

W96-7140 41 West 1996 Salomon Brothers, Inc. Typical

W97-7142 41 Core 1997 Salomon Brothers, Inc. Typical

W97-7153 41 North 1997 Salomon Brothers, Inc. Typical

W99-7177 41 Entire 1999 Salomon Smith Barney Typical

W99-7178 42 Entire 1999 Salomon Smith Barney Typical

W99-7178 42 Entire 1999 Salomon Smith Barney Typical

WOO-7111 43 Entire 2000 Salomon Smith Barney Typical, including new pre-action

system

WOl-7111 44 Entire 2001 Salomon Smith Barney Typical, including new pre-action

systems

W95-7195 45 North 1995 Salomon Brothers, Inc. Typical

8 NISTNCSTAR 1-11, WTC Investigation
Modifications to Fire Protection and Life Safety Systems

Table 2-1. Summary of modifications to WTC 7 fire protection

and life safety systems (continuec )•

TAA No. Floor(s)

Location on Floor Year Tenant Systems Modified

W99-7120 45 West 1999 Salomon Smith Barney Typical

W99-7194 45 East 1999 Salomon Smith Barney Typical

W93-7167,

W93-7168

46 Entire 1993,

1993

Salomon Brothers, Inc. Typical

W97-7196 46 South 1997 Salomon Brothers, Inc. Typical

WOO-7203 47 Northeast 2000 Salomon Smith Barney Typical

W93-7221 47 Northeast 1994 Salomon Brothers, Inc. Typical

W97-7140 47 East 1997 Salomon Brothers, Inc. Typical

WOO-7202 39 Entire 2000 Salomon Smith Barney Typical

W93-7102 39 Entire 1993 Salomon Brothers, Inc. Typical, includes egress analysis

for auditorium

W95-7173 39 Core 1995 Salomon Brothers, Inc. Typical

Key: TAA, Tenant Alteration Application.

NISTNCSTAR 1-11, WTC Investigation 9
Chapter 2

This page intentionally left blank.

10 NIST NCSTAR 1-11, WTC Investigation
Chapter 3

Structural Modifications due to Tenant Alterations

Structural modifications due to tenant alterations are listed in Table 3-1 . Included is a brief description of

the work that was perfonned with respect to the modifications. In most cases, members were reinforced

to accommodate floor loads that were greater than the loads for which these members were originally

designed.

In all of the cases cited in Table 3-1, structural calculations were included on the check of the existing

structural members and on the design of new structural members. In the documents related to the 1988

modifications, there were comments made by the Tenant Construction Review Unit of the Port Authority

of New York and New Jersey (PANYNJ or Port Authority) in regard to the project submittal. Also

included were responses from the structural engineer to the Port Authority on these comments. Similar

documents are available for the modifications made in 1999 on the 40th floor, which include a copy of the Tenant Construction or Alteration Application that was submitted to the Port Authority on behalf of the

tenant.

Tab e 3-1. Modifications made due to tenant alterations.

Date Floor(s) Tenant

Structural Engineer Description of Modification

Reference

Work

Order

Number

1988 38 Salomon

Brothers, Inc.

Office of

Irwin G. Cantor

Bottom and top cover plates were

added to the existing W24x55 beams

along column lines 37 and 40, and

bottom cover plates were added to the existing W24x55 beams along column

lines 30 and 35 to support new hanger

loads.

W-7004

PANYNJ

(Newark)

1989 24 General

Auditing

Office

^

Office of

Irwin G. Cantor

Bottom cover plates were added to the

existing W21x44 beam on column line 45 and the two adjacent W21x44 beams

to the west of column line 45 to support

additional load due to new file storage. The existing W36xl35 girder framing

between columns 76 and 79, which

supported these beams, was also reinforced with a bottom cover plate. ^

W-8003

PANYNJ

(Newark)

NISTNCSTAR 1-11, WTC Investigation 11
Chapter 3

Table 3-1. Modifications made due to tenant alterations (continued).

Date Floor(s) Tenant

Structural

Engineer Description of Modification

Reference

Work

Order

Number

1989 47 Salomon

Brothers, Inc.

Office of

Irw in G. Cantor

Bottom cover plates were added to the

existing W16x31 beam along column

line 2, the W16x26 beam along column

line 3, and the W14x22 beams along

column lines 4 and 5 to support

additional mechanical equipment. The

W33xl30 girder on column line 56,

which supported these beams, was

reinforced with bottom and top cover

plates.

W-7004

PANYNJ

(Newark)

1990 11, 12 Spicer &

Oppenheimer

Office of

Irwin G. Cantor

Bottom cover plates were added to eight existing beams and girders in the northwest comer of the building on the

1 1th floor to support larger live loads. Similarly, bottom cover plates were

added to three existing beams between

column lines 48 and 49 and the girder

between columns 70 and 73 on the 12th

floor.

W-8005

PANYNJ

(Newark)

1991 19 ITT Hartford Office of James Ruderman

Bottom cover plates were added to existing W24x55 and W24x76 beams

to support new files and shelves. Exact

location of these beams could not be

dptprmmpH from thp dnnimpntation

W-8010

PANYNJ

(Newark)

1992 12 Securities Exchange

Commission

Office of

Irwin G. Cantor

Bottom cover plates were added to eleven existing beams in the northwest comer of the building to support legal

filp*^ A npw W 1 '^x 1 9 bpam wa^i al<sn added between two of the existing

beams.

W92-7056

PANYNJ

(Newark)

1992 18, 19 Equal

Fnmlnvnipnt

Opportunity

Commission

Office of

Irwin 11 VV 111 Ci\J • Cantor

Bottom cover plates were added to

pxi'^tinp ^A/74 bp?im*s on thp 1 8th floor on column lines 31, 32, and 33 to support larger live loads.

W92-7150

1993 28 Salomon

Brothers, Inc.

Office of

Irwin G. Cantor

Eight additional shear studs were added

to an existing W16x26 beam located in the mechanical/electrical room to support new equipment loads.

W93-7138

PANYNJ

(Newark)

1993 7, 8 American

Express Bank

Office of James RudermanA new W12x1 4 beam located on the west side of the building between

column lines 7 and 8 was added on the

8th floor to support a new concrete masonry unit wall.

W93-7233

PANYNJ

(Newark)

12 NISTNCSTAR 1-11, WTC Investigation
structural Modifications Due to Tenant Alterations

Table 3-1. Modifications made due to tenant alterations (continued).

Date Floor(s) Tenant

Structural

Engineer Description of Modification

Reference

Work

Order

.Number

1994 7-29 Salomon

Brothers, Inc.

Office of

Irwin G. Cantor

Bottom cover plates were added to 22 existing beams between columns 5 and 25 on the south side of the building on each floor between levels 7 and 29

to support larger live loads. Similarly,

bottom cover plates were added to eight

beams on the east side of the building

between column lines 31 and 37 on

each of these floors.

W93-7232

1995 20 ITT Hartford The Cantor

Seinuk

Group

Bottom cover plates were added to the existing W16x26 beams along column

lines 23 and 25 to support new filing cabinets. Similarly, WT sections were welded to the bottom of the existing

W16x26 beams that framed in between

the above-mentioned beams.

WT sections were welded to the bottom

of the existing W16x26 beam east of

column line 18 and the W16x26 beam

on column line 19 to support new filing cabinets. Similarly, a bottom cover

plate was added to the existing W16x26

beam epst of column line 19.

W95-7153

1999 37 Salomon

Smith Barney

Gilsanz

Murray

Steficek

A new W16x40 beam was added

between two existing W14x22 beams

along column lines 76 and 77 to support a new high-density filing

system.

W99-7134

PANYNJ

(Newark)

1999 13 The Standard

Chartered Bank

The Cantor

Seinuk

Group

Ten additional shear studs were added

to an existing W24x55 beam to support

additional loads from a new file room

and a new UPS/LAN room. Exact

location of this beam could not be

determined from the documentation.

W99-

7137-02

PANYNJ

(Newark)

1999 40 Salomon

Smith Barney

Gilsanz

Murray

Steficek

Four new W18x35 beams were added

to support the new high-density files near column 76. WT4x20 sections were

welded to the bottom of two existing

W14x22 beams that supported the files. New W16x50 beams were connected

below to the existing W36xl35 girders

that supported the beams in this area.

W99-7172

PAIN YINJ (Newark)

NISTNCSTAR 1-11, WTC Investigation 13
Chapter 3

Table 3-1. Modifications made due 1to tenant alterations (continued).

Date Floor(s) Tenant

Structural

Engineer Description of Modification

Reference

Work

Order

Number

2000 31 Salomon

Smith Barney

Gilsanz

Murray

Steficek

Top and bottom cover plates were

added to an existing W27x94 beam

between columns 77 and 80 to support

a new high-density filing system. The

existing beam connections were also reinforced with stiffened seat connections.

WOO-7122

PANYNJ

(Newark)

2000 38 Salomon

Smith Barney

Gilsanz

Murray

Steficek

Bottom cover plates were added to existing W14x22 beams between

columns 76 and 77 and between

columns 77 and 78 to support a new

high-density filing system. Also, the following existing girders were

reinforced with bottom cover plates: ( 1

)

W36xl35 between columns 76 and 79,

(2) W27x94 between columns 77 and

80, and (3) W27x84 between columns

78 and 81.

WOO-7224

PANYNJ

(Newark)

2000 39 Salomon

Smith Barney

Gilsanz

Murray

Steficek

New W14x53 beams were added under

each rail of a new high-density filing

system in lieu of reinforcing existing

W14x22 beams between columns 76

and 77.

WOO-7202

PANYNJ

(Newark)

Key: WT, wide-flange T-sections.

14 NISTNCSTAR 1-1 i WTC Investigation
Chapter 4

Openings Made in Floor Slabs

4.1 DESCRIPTION OF THE MODIFICATIONS

According to the Base Building modifications (Cantor 1989) for World Trade Center 7, columns 76, 78,

79, 80, and 81 were reinforced with plates that ran from the top of the 39th floor to the underside of the 40th floor due to the removal of the floor slab at the 39th floor. Similarly, column 74 was reinforced with

plates that ran from the top of the 43rd floor to the underside of the 44th floor due to the removal of the

floor slab at the 43rd floor. These slabs were removed to accommodate the trading floors for Salomon

Brothers, Inc. Furthermore, it is stated in the Facility Condition Swvey Program report (PANYNJ 1 997),

that the 41st and 43rd floor slabs were completely removed on the east side of the building to accommodate the trading floors for Salomon Brothers, Inc. Structural modifications involving openings

made in the floor slabs are listed in Table 4—1. Included is a brief description of the work that was

performed with respect to the modifications.

Table 4-1. Openings made in floor slabs.

Date Floor(s) Tenant

Structural

Engineer Description of Modification

Reference

Work

Order

Number

1989 3,4 Salomon

Brothers, Inc.

Skidmore,

Owings &

Merrill

On the 3rd floor, openings were cut on

the west, north, and east sides of the building. New framing was introduced around these openings. On the 4th

floor, new openings and framing were

introduced on the north side of the building.

W-7004

PANYNJ

1989 3 Salomon

Brothers, Inc.

Office of

Irwin G. Cantor

Two 2 ft 6 in. by 3 ft 6 in. openings were cut near columns 24 and 25. New

C8xl 1 .5 framing members were added

around the openings.

W-7005

PANYNJ

(Newark)

1990 11 Spicer &

Oppenheimer

Office of

Irwin G. Cantor

A new stair opening was made between

columns 77. 78, 80, and 81 . New

W12x1 6 beams were added around the opening.

W-8005

PANYNJ

(Newark)

1994 43 Salomon

Brothers, Inc.

Skidmore,

Owings &

Merrill

A new slab opening was made near column 7 1 in the core area. New

beams were added around the opening.

W94-7746

Note: Structural calculations on the design of new structural members and on the check of the existing structural members were

included for the modification made in 1989 (3rd floor) and 1990.

NISTNCSTAR 1-11, WTC Investigation 15
Chapter 4

4.2 REFERENCES

Cantor (The Office of Irwin G. Cantor P.C.). 1989. "Salomon Brothers, Inc., Base Building

Modifications - 7 World Trade Center Structural Computations." W-7004, Port Authority. Newark,

January.

PANYNJ (The Port Authority of New York and New Jersey). 1997. Port Authority Facilit}' Condition

Survey Program - 7 World Trade Center. Engineering Quality Assurance Division, Engineering

Department. April.

16 NISTNCSTAR 1-11, WTC Investigation
Chapter 5

Modifications Made to Beam Webs and Flanges

Modifications made to beam webs and flanges are summarized in Table 5-1 . Included is a brief

description of the work that was performed with respect to the modifications.

Table 5-1. Modifications made to beam webs and flanges.

Date Floor(s) Tenant

oil Ui. lUI al Engineer Description of Modification

Reference

Work

Number

1993 28 Salomon

Brothers, Inc.

Office of

Irwin G. Cantor

Two 1 in. by 36 in. openings, located

3 ft apart, were cut into the web of an

existing W24x55 beam (unknown

location). Plates were welded on each

side of the web along the upper and

lower edges of the openings.

W93-7I38

PANYNJ

(Newark)

1993 4-7, 16, 21,

29,38,45

Salomon

Brothers, Inc.

Office of

Irwin G. Cantor

Notches were cut in the bottom flanges

of various beams on these floors to accommodate ductwork. Plates were

welded to the upper side of the bottom

flanges.

W93-7221

1998 1 Mayor's

Office of

Emergency

Management

The Cantor

Seinuk

Group

A notch was cut into the top flange of

an existing beam (unknown location).

Two plates, one on each side of the web, were welded under the top flange.

W98-1734

1999 36^4 Salomon

Smith Barney

The Cantor

Seinuk

Group

Two new openings (68 in. by 22 in. and

76 in. by 22 in.) spaced 3 ft 10 in. apart were cut into the web of the existing

W24x62 beam framing into column 75. Horizontal and vertical stiffener plates were added on all sides of the openings.

Also, a new WT15x74 section was

welded to the bottom of the beam. The

same size openings were made in an

existing W27x94 beam on the 43rd

floor, which was reinforced in a similar manner.

W99-7127

PANYNJ

(Newark)

1999 42, 44 Salomon

Smith Barney

Gensler New web openings were cut in numerous beams along the north and

east sides of the building.

W99-7127

NISTNCSTAR 1-11, WTC Investigation 17
Chapter 5

This page intentionally left blank.

18 NIST NCSTAR 1-11, WTC Investigation