NIST NCSTAR 1-1B

Federal Building and Fire Safety Investigation of the

World Trade Center Disaster

Comparison of Building Code

Structural Requirements

S. K. Ghosh

Xuemei Liang

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

NIST NCSTAR 1-1B

Federal Building and Fire Safety Investigation of

World Trade Center Disaster

Comparison of Building Code

Structural Requirements

S. K. Ghosh

Xuemei Liang

S. K. Ghosh 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 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 1-1B

Natl. Inst. Stand. Technol. Natl. Constr. Sfty. Tm. Act Rpt. 1-1B, 280 pages (September 2005)

CODEN: NSPUE5

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 provides a comparison of the structural provisions of: (1) the New York City Building Code,

1968 edition. (2) the New York City Building Code. 2001 edition, (3) the New York State Building

Construction Code, 1964 edition, (4) the Municipal Code of Chicago, 1967 edition, and (5) the Building

Officials and Code Administrators (known as BOCA) Basic Building Code, 1965 edition. Detailed

comparisons are provided in a tabular form. The comparisons are summarized in the body of the report.

Keywords: Code, construction, design, foundations, loads, materials, standards. World Trade Center.

NISTNCSTAR 1-1 B, WTC Investigation iii
Abstract

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

Abstract iii

List of Figures ix

List of Tables xi

List of Acronyms and Abbreviations xiii

Metric Conversion Table xv

Preface xix

Executive Summary xxix

Chapter 1 Introduction 1

Chapter 2 Codes included in Comparison 3

Chapter 3 Overview of Codes Compared 5

3.1 1968 and 2001 New York City Building Codes 5

3.2 1 964 New York State Building Code 6

3.3 1967 Chicago Municipal Code 6

3.4 1 965 BOCA-Basic Building Code 7

Chapter 4 Loads 9

4.1 Dead Loads 9

4.2 Floor Live Loads 10

4.3 Roof Live Loads 12

4.4 Moving Loads 12

4.5 Partial Loading Conditions 12

4.6 Roof Live Load Reduction 12

4.7 Floor Live Load Reduction 12

4.8 Wind Loads 16

4.9 Earthquake Loads 20

4.10 Snow Loads 21

4. 1 1 Soil and Hydrostatic Pressure 21

NISTNCSTAR 1-1B. WTC Investigation v
Table of Contents

4.12 Construction Loads 21

4.13 Fluid Pressures 22

4.14 Ice Loads 22

4.15 Thermal Forces 22

4.16 Shrinkage 22

4. 1 7 Distribution of Vertical and Horizontal Loads 22

Chapter 5 Structural Work.. 23

5.1 Standards 23

5.2 Aheration of Existing Buildings 23

5.3 Materials and Methods of Construction 24

5.4 Used and Unidentified Materials 25

5.5 Equivalent Systems of Design 25

5.6 Stability 25

5.7 Bracing 25

5.8 Secondary Stresses 26

5.9 Load Combinations 26

5.9.1 Allowable Stress Design 26

5.9.2 Ultimate Strength Design 27

5.10 Deflection Limitations 28

5.11 Load Tests/Core Tests 29

5.12 Exterior Wall Materials 29

5.13 Prefabricated Construction 29

5.14 Masonry Construction 29

5.15 Concrete 30

5.16 Steel 31

5.17 Wood ;....33

5.18 Aluminum 35

5.19 Reinforced Gypsum Concrete 35

5.20 Thin Shell and Folded Plate Construction 36

5.2 1 Suspended Structures 36

Chapter 6 Foundations 37

6 . 1 General Requirements 37

vi NISTNCSTAR 1-1 B, WTC Investigation
Table of Contents

6.2 Soil Investigations 37

6.3 Foundation Loads 38

6.4 Allowable Soil Bearing Pressures 38

6.5 Soil Load Bearing Tests 39

6.6 Footings, Foundation Piers, and Foundation Walls 39

6.7 Pile Foundations—General requirements 40

6.8 Pile Foundation—Loads 40

6.9 Pile Driving Operations 40

6.10 Pile Types - Specific Requirements 41

6.11 Underpinning 41

6.12 Stability 41

6.13 Inspection 41

Chapter 7 Detailed Comparison Tables 43

Chapter 8 Summary 45

Chapters

References 47

Annex A1

Reference Standards of 1968 New York City Building Code 173

Annex A2

Reference Standards of 2001 New York City Building Code 185

Annex A3

Reference Standards of 1964 New York State Building Construction Code 193

Annex A4

Reference Standards of 1967 Chicago Municipal Code 197

Annex A5

Reference Standards of 1965 BOCA Building Code 199

Annex B1

Tables in 1968 New York City Building Code 217

NISTNCSTAR 1-1B, WTC Investigation vii
Table of Contents

Annex B2

Tables in 2001 New York City Building Code 229

Annex B3

Tables in 1964 New York State Building Construction Code 231

Annex B4

Tables in 1967 Chicago Municipal Code 237

Annex 85

Tables in 1965 BOCA Basic Building Code 239

viii NISTNCSTAR 1-1B, WTC Investigation
List of Figures

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

disaster xxi

Figure 4-1. Reduced live load of various building codes for columns, walls, and piers 15

Figure 4-2. Minimum wind load (psf) on vertical surfaces required by various building codes 18

Figure 4-3. Minimum wind load (psf) as a function of height (ft) on vertical surfaces required by

1964 New York State Building Code 19

NISTNCSTAR 1-1B, WTC Investigation ix
List of Tables

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

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

Table 4-1 . Comparison of unifonn live load values of reviewed codes for types of live loads used

in design of WTC towers (psf) 1

1

Table 4-2. Reduced live load per the 1968 New York City Building Code Table 9-1 (percent) 13

Table 4-3. Reduced live load of various building codes for beams and girders 15

Table 4-3. Reduced live load of various building codes for beams and girders 16

Table 4-4. Design wind pressures on vertical surfaces per the 1968 New York City Building

Code (Table RS 9-5-1) 16

Table 4-5. Design wind pressures on horizontal and inclined surfaces per the 1968 New York

City Building Code (Table RS 9-5-2). 17

Table 4-6. Base shears and overturning moments (per ft of building width) from reviewed codes

for a building the height of WTC towers (1,368 ft) 20

Table 7-1 . Definitions 49

Table 7-2. Loads 63

Table 7-3. Structural Work 91

Table 7-4. Foundations 133

NIST NCSTAR 1-1 B, WTC Investigation xi
List of Figures

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X NIST NCSTAR 1-1 B, WTC Investigation
List of Tables

\

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

Acronyms

AA Aluminum Association

AASHO American Association of State Highway Officials

AASHTO American Association of State Highway and Transportation Officials ACI American Concrete Institute AF&PA American Forest and Paper Association

AITC American Institute of Timber Construction

AISC American Institute of Steel Construction

AISI American Iron and Steel Institute ANSI American National Standards Institute APA American Plywood Association

AREA American Railway Engineering Association

ASA American Standards Association

ASCE American Society of Civil Engineers

ASD Allowable Stress Design

ASTM ASTM International (formerly American Society for Testing and Materials)

AWPA American Wood-Preservers' Association

AWS American Welding Society

BBC Basic Building Code

BCB Building Code Bureau (State of New York)

BOCA Building Officials Conference of America (later Building Officials and Code

Administrators, International)

CS Commercial or Commodity Standards

DFPA Douglas Fir Plywood Association

FEMA Federal Emergency Management Agency

LRFD Load and Resistance Factor Design

NIST National Institute of Standards and Technology

NLMA National Lumber Manufacturers Association

NYC New York City

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

PCI Prestressed Concrete Institute RS reference standard

SJI Steel Joist Institute UBC Uniform Building Code

USASI United States of America Standards Institute use United States Code

USDA United States Department of Agriculture • 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

Abbreviations

°F degrees Fahrenheit

D effects of dead load

E effects of earthquake

F effects of weight and pressures of fluids with well-known densities and controllable maximum heights

ft foot

ft" square foot

in. inch

L effects of live load

min minimum

plf pounds per linear foot

psf pounds per square foot

psi pounds-force per square inch

RL effects of reduced live load

SH effects of shrinkage

T effects of thermal forces UL effects of unreduced live loads where live load reduction is permitted

W effects of wind load

Q the combination of any two or more of W, T, SH, and UL

^ strength reduction factor

xiv NISTNCSTAR 1-1 B, WTC Investigation
Metric Conversion Table

To convert from to Multiply by

AREA AND SECOND MOMENT OF AREA

square foot (ft')

square inch (in.")

square inch (in.')

square yard {yd')

square meter (m')

square meter (m')

square centimeter (cm')

square meter (m")

9.290 304 E-02

6.4516 E-04

6.4516 E+00

8.361 274 E-01

ENERGY (includes WORK)

kilowan hour (kW • h)

quad (1015 BtuIT)

therm fU.S.)

ton of TNT (energ>' equivalent)

watt hour (W h)

watt second (W - s)

joule (J)

joule (J)

joule (J)

joule (J)

joule (J)

joule (J)

3.6 E+06

1.055 056E+18

1.054 804 E+08

4.184 E+09

3.6E+03

1.0 E+00

FORCE

d\T\e (dyn)

kilogram-force (kgf)

kilopond (kilogram-force) (kp)

kipd kip= 1.000 IbO kipd kip= 1.000 IbO

pound-force (Ibf)

newton (N)

newton (N)

newton (N)

newion (N)

kilonewton (kN)

newton (N)

l.OE-05

9.806 65 E+OO

9.806 65 E+00

4.448 222 E+03

4.448 222 E+00

4.448 222 E+00

FORCE Dl\ IDED BY LENGTH

pound-force per foot (Ibf/ft)

pound-force per inch (Ibf'in.)

newlon per meter (N/m)

neulon per meter (N'm)

1.459 390 E+01

1.751 268 E+02

HEAT FLOW RATE

calorieth per minute (calth'min)

calorieth per second (calth's)

kilocalorieth per minute (kcalth/min)

kilocalorieth per second (kcalth/s)

watt (W)

watt(W)

watt(W)

watt(W)

6.973 333 E-02

4.184 E+00

6.973 333 E+01

4.184 E^03

NISTNCSTAR 1-1B. WTC Investigation XV
Metric Conversion Table

To convert from to Multiply by

LENGTH

foot (ft)

inch (in)

inch (in.)

micron (m)

yard (yd)

meter (m)

meter (m)

centimeter (cm)

meter (m)

meter (m)

3.048 E-01

2.54 E-02

2.54 E+00

l.OE-06

9.144 E-01

MASS and MOMENT OF INERTIA

kilogram-force second squared

per meter (kgf • s"/m) kilogram (kg) 9.806 65 E+00

pound foot squared (lb ft") kilogram meter squared (kg m") 4.214 011 E-02

pound inch squared (lb in.") kilogram meter squared (kg • m") 2.926 397 E-04

ton, metric (t) kilogram (kg) l.OE+03

ton, short (2,000 lb) kilogram (kg) 9.071 847 E+02

MASS DIVIDED BY AREA

pound per square foot (lb/ft") kilogram per square meter (kg/m") 4.882 428 E+00

pound per square inch

(nol pound force) (lb/in.") kilogram per square meter (kg/m") 7.030 696 E+02

MASS DIVIDED BY LENGTH

pound per foot (lb/ft) kilogram per meter (kg/m) 1.488 164 E+00

pound per inch (lb/in.) kilogram per meter (kg/m) 1.785 797 E+01

pound per yard (lb/yd) kilogram per meter (kg/m) 4.960 546 E-01

PRESSURE or STRESS (FORCE DIVIDED BY AREA)

kilogram-force per square centimeter (kgf/cm") pascal (Pa)

kilogram-force per square meter (kgf/m") pascal (Pa)

kilogram-force per square millimeter (kgf/mm") pascal (Pa)

kip per square inch (ksi) (kip/in.") pascal (Pa)

kip per square inch (ksi) (kip/in.") kilopascal (kPa)

pound-force per square foot (Ibf/ft") pascal (Pa)

pound-force per square inch (psi) (Ibf/in.") pascal (Pa)

pound-force per square inch (psi) (Ibf/in.") kilopascal (kPa)

psi (pound-force per square inch) (Ibf/in.") pascal (Pa)

psi (pound-force per square inch) (Ibf/in.") kilopascal (kPa)

9.806 65 E+04

9.806 65 E+00

9.806 65 E+06

6.894 757 E+06

6.894 757 E+03

4.788 026 E+01

6.894 757 E+03

6.894 757 E+00

6.894 757 E+03

6.894 757 E+00

XVI NISTNCSTAR 1-18, WTC Investigation
Metric Conversion Table

To convert from

TE.MPER.4TLRE

degree Celsius (°C)

degree centigrade

degree Fahrenheit (°F)

degree Fahrenheit (°F)

kelvin (K)

TEMPER.4TL RE INTERVAL

degree Celsius CC)

degree centigrade

degree Fahrenheit (°F)

degree Fahrenheit (°F)

degree Rankine (°R)

VELOCITY (includes SPEED)

foot per second (fVs)

inch per second (in./s)

kilometer per hour (km/h)

mile per hour (miTi)

mile per minute (mi min)

VOLUME (includes CAPACITY)

cubic foot (ft'^)

cubic inch (in.' )

cubic yard (yd')

gallon (U.S.) (gal)

gallon (U.S.) (gal)

hter(L)

ounce (U.S. fluid) (fl oz)

ounce (U.S. fluid) (fl oz)

to

kelvin (K)

degree Celsius (°C)

degree Celsius (°C)

kelvin (K)

degree Celsius (°C)

Multiply by

T/K = t/°C + 273.15

t/°C = t /deg. cent.

t/°c = (t/°F- 32)/1.8 T/K = (t/°F + 459.67)/1.8

t/°C = T/'K 2 273.15

kelvin (K) l.OE+00

degree Celsius (°C) 1 .0 E+00

degree Celsius (°C) 5.555 556 E-01

kelvin (K) 5.555 556 E-01

kelvin (K) 5.555 556 E-01

meter per second (m/s) 3.048 E-01

meter per second (m/s) 2.54 E-02

meter per second (m's) 2.777 778 E-01

kilometer per hour (kmTi) 1 .609 344 E+00

meter per second (m/s) 2.682 24 E+01

cubic meter (m')

cubic meter (m')

cubic meter (m')

cubic meter (m')

liter (L)

cubic meter (m')

cubic meter (m')

milliliter (mL)

2.831 685 E-02

1.638 706 E-05

7.645 549 E-01

3.785 412 E-03

3.785 412 E+00

1.0 E-03

2.957 353 E-05

2.957 353 E+01

NISTNCSTAR 1-1B. WTC Investigation xvu
Metric Conversion Table

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XVlll NISTNCSTAR 1-18, WTC Investigation
Preface

Genesis of This Investigation

Immediately following the terrorist attack on the World Trade Center (WTC) on September 11, 2001, the Federal Emergency Management Agency (FEMA) and the American Society of Civil Engineers began

planning a building perfomiance 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 deteraiine 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 in\ estigate the building construction, the materials used, and the technical conditions that contributed to the outcome of the WTC disaster.

• To serv e 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 re\ isions 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 uhy 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 1-1 B, WTC Investigation XIX
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

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 Public

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 sewed 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-I, 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 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.

XX NISTNCSTAR 1-1B, WTC Investigation
Preface

NIST WTC Investigation Projects

IMISr

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 1-1B, WTC Investigation xxi
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 Infonnation 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 commentaiy 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 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 preliminai-y findings, and obtain comments on the direction and

progress of the Investigation from the public and the Advisoiy 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 thi-ee-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-stoi-y 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.

xxn NIST NCSTAR 1-1B, WTC Investigation
Preface

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

Date Location Principal Agenda

Tune ""-l ''00'' June — — vjv/— New Ynrlr Citu NY rUUlIL IIlCCllll^. r UUilC LUIIlIlldUo UIl lllc LJt U/l J lUtl iUI lUC pending WTC Investigation.

A iioiist ">

1 ''Of)'' l» ^5 1 1 nerc ni iro \y1ll IVlcUld UIICIIU^ alUlUUIlLlIl^ IIIC lUlIlld.1 dial t Ul UlC 111 v CMl^allUll.

vv aolllimiUli, LJ\- iVlCUia UllCilllg UIl IClCdbC Ul lllC lUUllL LJyUUlc aliU 1 ICm^CSl

for photographs and videos.

Anril 8 Tini Npw YnrW Tifv NY JUIIU pUUIIL lUlUIIl Willi l^UIUlllUIa UIllVCIMiy UIl I II M-pCl bull interviews. Gaithersburg, MD NCST Advisory Committee meeting on plan for and progress on WTC Investigation with a public comment session.

.via\ /. zuuj New \ ork City. NY Media briefing on release of Mciv 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 ofJune 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 UnderuTiters 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 oi all draft reports for the WTC towers and draft recommendations for public comment.

September 12-13. 2005Gaithersburg, 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 1-1B, WTC Investigation XXlll
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 1 A. 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 ofthe World Trade Center Disaster: Design and Construction ofStructural Systems.

NIST NCSTAR 1-lA. 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 I -IC. 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 1, 2, and 7 and Post-Construction Provisions Applied after Occupancy. NIST NCSTAR 1 -ID. National Institute of Standards and Technology. Gaithersburg,

MD, September.

Razza, J. C, and R. A. Grill. 2005. Federal Building and Fire Safet}> 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

xxiv NIST NCSTAR 1-18, 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 City Building Code by Local Laws Adopted While World Trade Center 1, 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 I 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 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 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 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 1-1 B, WTC Investigation XXV
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 Safet}' 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 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 Safet}' 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 I -5 A. National Institute of Standards and Technology. Gaithersburg, MD,

September.

xxvi NIST NCSTAR 1-1 B, WTC Investigation
Preface

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

J. Yang, G. MulhoUand, 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 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 of the 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 Safet}>

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 Stmcture Interface and Thermal Response of the 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 1-1B, WTC Investigation xxvii
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 Safet)' 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 of the World Trade

Center Disaster: Analysis ofPublished Accounts of the 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.

xxviii NIST NCSTAR 1-1 B, WTC Investigation
Executive Summary

This report provides a comparison of the structural provisions of the 1968 New York City Building Code,

which was used in the design of the World Trade Center (WTC) towers, with those of three contemporaneous building codes as well as the 2001 edition of the New York City Building Code, which

is currently in effect. The contemporaneous codes chosen for comparison were:

1. The New York State Building Construction Code, 1964 edition,

2. The Municipal Code of Chicago, 1967 edition, and

3. The Building Officials and Code Administrators (BOCA) Basic Building Code (BBC),

1965 edition.

The New York State code was chosen as the building code in effect in the State of New York at the time

the WTC towers were designed. The Chicago code was chosen as the code then in effect in a large city

with tall buildings outside of the northeastern states where the WTC towers are located. The BOCA code was chosen as the model code t\'pically adopted at that time in the northeastern states.

Structural provisions include those concerning design loads, materials and methods of construction,

design methods including design load combinations, the major materials of construction (concrete,

masonry, steel, and wood), and design and construction of foundations. Detailed comparisons of

provisions are provided in the form of tables. The comparisons are summarized in the body of this report.

A comparison is provided of uniform design live load values from the reviewed codes for the types of live load (on different floor areas) used in the design of the WTC towers. A summary is provided of the live load reductions permitted by the various codes for columns, walls, piers, beams, and girders. The New

York City Building Codes have live load reduction provisions based on contributory floor area and live- to-dead load ratio. For li\ e-to-dead load ratios of 0.625 or less, these provisions may yield higher live load reductions than the other codes. The same comments do not apply to the alternative live load

reduction provision of the New York City Building Codes.

Based on the comparison of minimum wind loads on vertical surfaces required by the various building

codes, the largest shear force at the base of a building the height of the WTC towers is obtained from the BOCA-BBC. Similarly, the largest overturning moment at the base of a building the height of the WTC

towers is also obtained from the BOCA-BBC. The lowest base shear and moment are obtained from the 1968 and 2001 New York City Codes. The base shear from the New York City Codes is approximately

20 percent less than that from BOCA, while the base moment is approximately 10 percent less.

Of the codes compared, only the 2001 New York City Building Code and the BOCA-BBC have seismic

design provisions. Those provisions are based on the 1988 edition (including the 1990 Accumulative

Supplement) and the 1962 edition of the Uniform Building Code, respectively (ICBO 1962, ICBO 1988).

NISTNCSTAR 1-1B. WTC Investigation XXIX
Executive Summary

The primary materials standards referenced in the 1 968 New York City Building Code, the Chicago

Municipal Code, and the BOCA-BBC are the 1963 edition of ACl 318, Building Code Requirements for

Reinforced Concrete, and the 1963 edition of the AISC specification. Specifications for the Design,

Fabrication and Erection ofStructural Steel for Buildings. The New York State Building Code, being a perfomiance code, does not adopt any standards by reference. The 2001 New York City Building Code

references updated steel and concrete standards.

The New York City Building Codes have extensive and rigorous foundation design and construction

requirements; the other codes are less extensive and typically less rigorous.

XXX NISTNCSTAR 1-1B, WTC Investigation
Chapter 1 Introduction

The objecti\ e of this study was to examine how the structural provisions of the 1968 edition of the New

York City Building Code, which was used in the design of World Trade Center (WTC) 1 and WTC 2, compared with the structural provisions in a number of contemporaneous codes, as well as in the 2001

edition of the New York City Building Code, which is currently in effect. One of the selected contemporaneous codes was the building code in effect in the State of New York at the time WTC 1 and

WTC 2 were designed. Another selected code was the building code then in effect in Chicago, which

represented a large city with tall buildings outside of the northeastern states where the WTC towers are

located. The third code selected was the model building code that was typically adopted in the northeastern states at the time the WTC towers were designed. Thus, this report provides a comparison of

the structural provisions of the following codes:

1. The New^ York City Building Code, 1968 edition (The City of New York 1968)

2. The New York City Building Code, 2001 edition (The City of New York 2001

3. The New York State Building Construction Code, 1964 edition (BCB 1964)

4. The Municipal Code of Chicago, 1967 edition (The City of Chicago 1967)

5. The BOCA Basic Building Code, 1965 edition (BOCA 1965)

Structural provisions include those concerning design loads, such as dead loads, live loads (including Hve

load reduction), wind loads, earthquake loads and other loads. They also include provisions concerning

what is called "structural work" in the New York City Building Codes (this term is not used in the other

codes). The scope of "structural work" includes, but is not limited to, materials and methods of

construction, design methods including design load combinations, and the materials of construction

including concrete, masonry, steel and wood. Structural provisions also include those for foundation

design and construction.

Detailed comparisons are provided in Tables 7-1 through 7^. The comparisons are based on detailed

section-by-section, subsection-by-subsection reviews of comparable provisions in the five codes included

in this study. There is a "Conunents" column in each table, which summarizes the differences among the

five codes. The comparisons are summarized in the body of this report.

NISTNCSTAR 1-1B. WTC Investigation 1
Chapter 1

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2 NIST NCSTAR 1-1B. WTC Investigation
Chapter 2

Codes included in Comparison

The Port of New York Authority (whose name was changed to the Port Authority of New York and New

Jersey in 1972 and which will be referred to as "the Port Authority") is not required to comply with the

local building code. As an interstate compact created under a clause of the U.S. Constitution, it is not bound by the authority having jurisdiction, which in the case of the World Trade Center (WTC) would be

the New York City Department of Buildings. In 1963, the Port of New York Authority, however,

instructed the architect and consulting engineers to prepare their designs for WTC 1 and WTC 2 to comply with the New York City Building Code.' Although it is not explicitly stated in the 1963 letter, the 1938 edition of the Code was in effect at the time. In areas where the Code was not explicit or where

technological advances made portions of it obsolete, the Port Authority directed the consultants to propose designs "based on acceptable engineering practice," and required them to inform the WTC

Planning Division when such situations occurred.

In 1965, the Port Authority instructed the design consultants for WTC 1 and WTC 2 to comply with the second and third drafts of the revised New York City Building Code then being finalized and to undertake

any design re\ isions necessary to comply with such provisions.' The new edition of the New York City

Building Code became effective in December 1968 (The City of New York 1968).

A consortium of Seven World Trade Company and Silverstein Development Corporation designed and

constructed WTC 7 as a Port Authority "Tenant Alteration" project. This was veiy different from the cases of WTC 1 and WTC 2. Section 5 A. 3 of the WTC 7 project specifications (WTC 7 Project

Specifications 1984) required the structural steel to be designed in accordance with the New York City

Building Code in effect at the time and the latest edition of the Specifications for the Design, Fabrication

and Erection ofStructural Steelfor Buildings published by the American Institute of Steel Construction.

When the building was designed in the 1980s, the 1968 edition of the New York City Building Code with

amendments was in effect; no revisions were made to the applicable structural provisions in the New

York City Building Code until 1987.

The building code in effect in the State of New York at the time WTC 1 and WTC 2 were designed was

the New York State Building Construction Code, 1964 edition.

To compare with contemporaneous building code requirements in a major U.S. city with tall buildings

outside of the northeastern states at the time the WTC towers were being designed, the structural provisions of the 1967 edition of the Municipal Code of Chicago are included in this review.

' Letter dated May 15, 1963, from Malcolm P. Levy (Chief, Planning Division, World Trade Department) to Minoru Yamasaki

(Minoru Yamasaki & Associates).

- Letter dated September 29, 1965, from Malcolm P. Levy (Chief, Planning Division, World Trade Department) to Minoru

Yamasaki (Minoru Yamasaki & Associates).

NISTNCSTAR 1-1B. WTC Investigation 3
Chapter 2

In the northeastern region of the United States, which includes the WTC site, the model code typically

adopted by local jurisdictions was the Building Officials and Code Administrator (BOCA) National

Building Code. This code, prior to the mid-1980s, was called the BOCA Basic Building Code (BBC).

The 1965 edition of the BOCA BBC was the latest edition published at the time the WTC towers were

being designed.

The 2001 edition of the New York City Building Code is also included in this review, as it is the latest edition in effect at the time of this writing.

Thus, this report provides a comparison of the structural provisions of five building codes: the 1968 and

2001 editions of the New York City Building Code, the 1964 edition of the New York State Building

Code, the 1967 edition of the Municipal Code of Chicago, and the 1965 edition of the BOCA BBC.

Tables 7-1 through 1-A of this report provide detailed comparisons of the structural provisions of the five codes. The reference standards mentioned in the comparisons are listed in Annex Al through Annex A5.

The code tables mentioned in the comparisons are included in Annex Bl through Annex B5. This report

summarizes the detailed comparisons presented in Tables 7-1 through 7^.

4 NISTNCSTAR 1-1 B, WTC Investigation
Chapter 3

Overview of Codes Compared

3.1 1968 AND 2001 NEW YORK CITY BUILDING CODES

The report dated June 28, 1968, of the Committee on Buildings to the City Council (The City of New

York Committee on Buildings 1968), which favored the adoption of the proposed 1968 Building Code,

stated: "Since the existing Building Code was first adopted in 1938, technology has undertaken major

re\ olutionarv' shifts, producing new materials and methods. Also, workable standards have now been

developed and perfected for describing and testing the desired characteristics of materials." It was

concluded that there would be nothing to gain by attempting to revise the 1938 code. "Rather an entirely new code should be written." It was decided that the new code should be a combination of perfonnance

and prescriptive requirements with strong emphasis on performance, whenever possible, and with liberal reference to acceptable national standards. In the opinion of the Cornmittee on Buildings, the new code

thoroughly "futurized" the building laws for the City of New York. In the words of the Committee

Chairman, "New construction techniques in New York will only be inhibited by technology itself"

The structural provisions of the 1 968 Code are contained principally in Articles 9 through 1 1 and

Article 19. Compared with the 1938 Code, the new structural provisions modernized the method of load

analysis and mandated specific consideration of previously neglected phenomena such as thennal forces

and shrinkage. Certain loads, such as for private dwellings and roofs, were decreased while wind loads were increased. In view of more rigorous requirements for structural analysis, allowable temporary

overstresses were increased. The 1 968 code prescribed an approach of performance engineering design,

as contrasted with the empirical and prescriptive methods of the 1938 Code. The 1968 Code permitted all modem design concepts including ultimate strength analysis, prestressed concrete, shell and folded plate

design, cable suspension, reinforced masonry and structural plywood. The foundation provisions made

foundation design much less stringent. Increased foundation loads (in instances, conceivably many times

previous limits) were permitted; however, the evaluation procedure was thorough and rigorous. The subsoil evaluation procedures were revised to produce more meaningful infomiation, and a uniform system

of soil classification was adopted. A five-point procedure for determining pemiissible pile loads was

established. Provisions regarding safety of the public and property during construction were revised and

unified in Article 1 9. Rigorous procedures for control of cranes, power buggies and power equipment were newly mandated.

TTie structure of the City of New York Building Code has two unique features. First, the code is continually updated by incorporating "local laws" that are approved by the City Council. For instance, in the 2001 edition of the New York City Building Code, Reference Standard RS 10-3 is ACI 318-83

^'Building Code Requirements for Reinforced Concrete,'" but the user finds the following statement: "repealed by Local Law 17/1995, eff. 2/21/96. See other Reference Standard RS 10-3 below, added by

Local Law 17/1995, eff 2/21/96." The other Reference Standard RS 10-3 is ACI 318-89 ''Building Code

Requirements for Reinforced Concrete.''

NISTNCSTAR 1-1 B, WTC Investigation 5
Chapter 3

The second unique feature is the way Reference Standards (RS) are used. The substantive provisions of

the code are supplemented by the Building Code Reference Standards, which are designated as "Building

Code Rules." The text of certain reference standards is printed in full. The text of other standards is incorporated by reference to their national designation. However, code modifications to these standards

are permitted. There are approximately 300 reference standards. The Building Code Rules may be

revised by an administrative procedure. The Board of Standards and Appeals is empowered to amend or

revise the building code rules or issue new building code reference standards consistent with the remainder of the code only upon an application by the Building Commissioner and only within the scope

of the application.

The New York State Building Construction Code (Code) is promulgated by the State Building Code

Council of the State of New York. The State Building Code Council is concerned with regulations for the construction of buildings and the installation therein of equipment that is essential to building operation

and maintenance. The purpose of its regulations is to establish reasonable safeguards for the safety,

health, and welfare of the occupants and users of buildings.

The municipalities of the State of New York have the option to adopt the State Building Construction

Code. The administration and enforcement of the Code are the responsibility of the local municipality

pursuant to its administrative ordinances.

In addition to the Code, the Council publishes a Code Manual to assist in the application and enforcement

of the Code. The Code Manual indicates and illustrates acceptable methods of compliance with the performance requirements set forth in the Code, but does not exclude other possible methods of meeting

these requirements. Where adopted, the Code is the law; the Code Manual is not.

As a further guide in determining compliance with the performance requirements of the Code, the Council

publishes a list of Generally Accepted Standards. Compliance with these standards is deemed to satisfy

code requirements.

The Chicago Municipal Code comprises the ordinances of the City of Chicago on building construction

and maintenance. In addition, it includes regulations for environmental control, sidewalks and fire prevention for new construction or major alteration projects.

The structural provisions of the 1967 Chicago Municipal Code are to be found in Chapters 68, 69, and 70. Section 69.4 contains a list of referenced standards. The standards for (a) foundations, (b) masonry, (c) wood, (d) reinforced concrete, (e) reinforced gypsum, (f) steel and metals, (g) plastering, and (h) single

family dwellings represent accepted engineering practice.

The regulations of the Chicago Municipal Code are subject to amendment by the Chicago City Council.

To keep users abreast of such amendments, the publisher of the code issues a periodic supplement.

3.2 1964 NEW YORK STATE BUILDING CODE

3.3 1967 CHICAGO MUNICIPAL CODE

6 NISTNCSTAR 1-1 B, WTC Investigation
Overview of Codes Compared

3.4 1965 BOCA-BASIC BUILDING CODE

The BOCA-Basic Building Code (BBC) published by the Building Officials Conference of America, Inc. (BOCA, later Building Officials and Code Administrators International) is one of three model codes that used to, and in many cases still do, fonn the basis of the building codes of various local jurisdictions. The

BOCA-BBC has been the model code of choice in the northeastern region of the United States, which

includes the cities of New York and Chicago. The City of New York has never adopted the BOCA-BBC

or any model code (with the exception of the earthquake design provisions of the 1988 Unifomi Building

Code (ICBO 1988), which were adopted in later versions of the code). The City of Chicago has used the BOCA-BBC as a basis for its municipal code, but it has never made a complete adoption, as for instance

the State of New Jersey has done.

The BOCA-BBC provisions are written in terms of performance, and not in the fonn of prescriptive

requirements for materials and methods. Performance-based codes make it easier to accept new materials

and methods of construction that can be evaluated by accepted standards.

The BOCA-BBC accepts nationally recognized standards as the criteria for evaluation of minimum safe practice or for determining the performance of materials or systems of construction. The application of

these standards is stated in the text of the code requirements, but the standards are listed and identified in the appendixes to the code. This makes it convenient to update any standard as it is revised or reissued by

the standards development organization.

NISTNCSTAR 1-1B. WTC Investigation 7
Chapter 3

This page intentionally left blank.

8 NISTNCSTAR 1-1B, WTC Investigation
Chapter 4

Loads

Article 9 of the 1968 New York City Building Code contains the minimum loads to be used in the design

of buildings. According to Section C26-900.2. Reference Standards (RS), the minimum dead, live, and

wind loads prescribed in Reference Standard RS 9. Loads (Annex Al of this report), are a part of Article

9. In no case are the loads used in design to be less than the minimum values contained in that article. The 2001 New York City Building Code has the same provision.

The 1964 New York State Building Code requires that loads include dead load and the following imposed

loads where applicable: hve, snow, wind, soil pressure including surcharge, hydrostatic, and impact.

Notice that earthquake loads are not mentioned. The Chicago Municipal Code prescribes minimum

design loads, including dead loads. The 1965 BOCA Basic Building Code (BOCA-BBC) prescribes all superimposed hve and special loads in addition to dead load.

4.1 DEAD LOADS

1968 and 2001 Sew York City Building Codes—Dead loads are defined in Sub-Article 901.0, Dead

Loads, of the 1968 New York City Building Code, as the actual weight of the building materials or construction assemblies to be supported, based on the unit weights provided in Reference Standard

RS 9-1, Minimum Unit Dead Loads for Structural Design Purposes (Section C26-901.1). Weights in pounds per square foot (psf) of floor area are listed for various types of walls and partitions, floor finishes and fills, ceilings, roof and wall coverings, and floors (wood joist construction). The densities of

miscellaneous materials are also given. Actual weights may be determined by analysis or from data in manufacturers" drawings and catalogs, but in no case are the unit weights permitted to be less than those

contained in Reference Standards RS 9-1, unless the building coinmissioner approves them. The 2001

New York City Building Code has the same provision.

According to the 1968 New York City Building Code, weights from service equipment (plumbing

stacks; piping; heating, ventilation, and air conditioning; etc.) are to be included in the dead load

(Section C26-901.2). The weight of equipment that is part of the occupancy of a given area is to be

considered as live load. TTie 2001 New York City Building Code has the same provision.

The 1968 and 2001 New York City Building Codes require that weights of all partitions be considered,

using actual weights at locations shown on plans. The equivalent uniform partition loads in Reference

Standard RS 9-1 (Annex Al of this report) may be used in lieu of actual partition weights, except in stipulated situations, where actual partition weights must be used. Equivalent uniform loads must be used

in areas where locations of partitions are not shown on plans, or in areas where partitions are subject to rearrangement and relocation.

New York State Building Code—There are no provisions similar to those of the New York City Building

Code concerning dead loads. There is no provision concerning equipment weight. There is also no

provision concerning partition loads.

NISTNCSTAR 1-1 B, WTC Investigation 9
Chapter 4

Chicago Municipal Code—There are no provisions similar to those of the New York City Building Code

concerning dead loads. There is no provision concerning equipment weight. A minimum partition load

of 20 psf is prescribed.

BOCA-BBC—The 1965 BOCA-BBC requires actual weights of materials to be used in estimating dead

loads, but the actual weights cannot be less than the unit dead loads prescribed in Appendix J of the code

(Annex A5 of this report). The BOCA-BBC has a provision concerning equipment weight that is similar

to the corresponding provisions of the New York City Building Code. The BOCA code requires

consideration of the actual weight of the partitions or an equivalent uniform load of no less than 20 psf of

floor area.

4.2 FLOOR LIVE LOADS

1968 New York City Building Code—Requirements for live loads are given in 902.0, Live Loads, of the 1968 New York City Building Code, with specific requirements for floor live loads given in C26-902.2.

Minimum design values for uniformly distributed and concentrated floor live loads for various

occupancies are contained in Reference Standard RS 9-2 (Annex Al of this report), Minimum

Requirements for Unifonnly Distributed and Concentrated Live Loads (Section C26-902.2). For

occupancies that are not listed, design live loads are to be detennined by the architect or engineer subject

to approval by the building commissioner. Provisions are also given on how to apply concentrated live loads so as to produce maximum stress in the structural elements.

2001 New York City Building Code—The live load provisions in the 1968 Code remained unchanged.

New York State Building Code—This code states that uniformly distributed and concentrated live loads

must be the greatest loads provided by the intended occupancy and use, subject to minimum values listed in Table C304-2.2 (Annex B3 of this report). Minimum loads for occupancies and uses not listed are to be in confoniiity with generally accepted standards.

Chicago Municipal Code—The minimum uniforaily distributed and concentrated live loads are given in Table 68-2.1 (Annex B4 of this report).

BOCA-BBC—The minimum uniforaily distributed and concentrated live loads are given in Table 13 (Armex B5 of this report).

Table 4-1 of this report provides a comparison of uniforai live load values of the codes reviewed for types of live loads used in the design of World Trade Center (WTC) 1 and WTC 2 (see Section 2.2.1,

NCSTAR 1-lA).'

The New York City Building Codes give the most comprehensive provisions for roofs subjected to special loads.

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

to this report.

10 NIST NCSTAR 1-1B, WTC Investigation
Loads

Table 4-1 . Comparison of uniform live load values of reviewed codes for types of live

loads used in design of WTC towers (psf)

Use of Spaces

1968 and

2001

NYC Codes

1964 NY

State Code

1967

Chicago

IXliinirin^il Code

1965

BOCABBC

Cafeteria 100 100 100 100

Closets (tenant floors) 100 120 100 125 Concourse 100 100 100 100

Corridors within core (mechanical equipment

floor)

75 100 NA NA

Corridors within core (sk\'lobby floor) 100 100 100 100

Corridors within core (typical office floor) 75 100 75 100 Duct offset space 75 100 NA NA

Electric closet 75 100 100 125

Electric substation & transformer room 75 100 NA NA

Elevator machine room (plus elevator reactions) (a) 100 NA 100

Elevator pits (plus elevator reactions) (a) 100 NA NA

Expansion tank room 75 100 NA NA

Janitor's closets 100 120 100 125

Kitchen 100 100 75 100

Local passenger elevator lobbies (skylobby floors) 100 100 100 100 Main shuttle elevator lobbies (skylobby floors) 100 100 100 100

Mechanical equipment rooms 75 100 NA NA

Men's toilets 40 60 NA NA

Observation lobby 100 100 100 100

Office areas 50 50 50 50

Passenger elevator lobbies (tenant floors) 100 100 100 100 Powder rooms 40 60 NA NA

Restaurant 100 100 100 100 Roof 30 20 25 20

Secondarv' motor rooms 75 100 NA NA

Service room'' (mechanical ecfuipment floor) 75 100 NA NA

Ser\ice room (tenant floor) 75 100 NA NA

Sprinkler tank room 75 100 NA NA

Stairs 75 100 100 100 Telephone closets 80 NA NA NA

Tenant spaces within core 50 50 50 50

a. Refers to ANSI ASME Al 7. 1

b. Considered as mechanical equipment rooms. Key: NA, not available.

NISTNCSTAR 1-1B, WTC Investigation 11
Chapter 4

4.3 ROOF LIVE LOADS

1968 and 2001 New York City Building Codes—Roof live load of 30 psf of horizontal projection,

reduced by 1 psf for each degree of slope in excess of 20 degrees, is prescribed. The concentrated load

provisions of Section C26-902.2 (b) apply.

New York State Building Code—On roofs not used as promenades, the minimum imposed load must be

20 psf perpendicular to the roof surface, where snow plus wind loads total less than 20 psf.

Chicago Municipal Code—The prescribed value is 25 psf of roof area, acting nornial to roof surface (this

includes snow). May be taken as zero for roofs having a pitch of 30 degrees or more.

BOCA-BBC—The roof live load is 20 psf of horizontal projection. In areas subject to snow loads, it is 30 psf of horizontal projection.

4.4 MOVING LOADS

Only the New York City Building Codes have provisions on moving loads, such as vehicles and

machineiy, which are detailed in Table 7-2 of this report.

4.5 PARTIAL LOADING CONDITIONS

The New York City Building Codes give simplified methods and the most detailed provisions concerning

partial loading conditions (not all spans loaded at the same time with the full design Hve loads). The

Chicago Municipal Code is the only other code that gives provisions that are general in nature.

4.6 ROOF LIVE LOAD REDUCTION

The New York State Code is the only code that allows roof live load reduction. The New York City,

Chicago, and BOCA codes do not allow any reduction for roof live load.

4.7 FLOOR LIVE LOAD REDUCTION

1968 New York City Building Code—Provisions for live load reduction are contained in 903.0, Live

Load Reduction. The allowable reduced live load for floor members is detennined by multiplying the basic live load value from Reference Standard RS 9-2 by the percentages given in Table 9-1 of the Code,

which is reproduced here as Table 4—2. These percentages are a function of the contributory floor area, which is defined in Section C26-903.3, and the ratio of live load to dead load.

12 NISTNCSTAR 1-1B. WTC Investigation
Loads

Table 4-2. Reduced live load per the 1968 New York City Building Code Table 9-1

(percent).

Contributorv Area

(fr)^

Ratio of Live Load to Dead Load"

0.625 or Less 1 2 or More

149 or less 100 100 100

] 50-299 80 85 85 300-449 60 70 75 450-599 50 60 70 600 or more 40 55 65

a. For intermediate \ alues of li\'e load dead load, the applicable percentages of live load may be interpolated.

b. ContributorN' areas are computed as follows (see Section C26-903.3): For one-way and two-way slabs: product of the shorter span length and a w idth equal to one-half the shorter span

length. Ribbed slabs shall be considered as though the slabs were solid. For flat plate or flat slab construction; one-half the area of the panel. For columns, girders, or trusses framing into columns: the loaded area directly supported by the column, girder, or

truss. For columns supporting more than one floor, the loaded area shall be the cumulative total area of all the floors

that are supported. For joists and similar multiple members framing into girders or trusses, or minor framing around openings: twice the loaded area directly supported but not more than the area of the panel in which the framing occurs.

No live load reduction is permitted for members and connections (other than columns, piers, and walls)

supporting:

• Floor areas used for storage (including warehouses, library stacks, and record storage);

• Areas used for parking of vehicles;

• Areas used as places of assembly, for manufacturing, and for retail or wholesale sales.

The maximum live load reduction is 20 percent for columns, piers and walls supporting such areas.

Live load reduction is also not permitted for calculating shear stresses at the heads of columns in flat slab or flat plate construction. Flat slabs and flat plates are reinforced concrete slabs supported directly on

columns, without any beams along the column lines. The provision applies only at the joints of such

slabs and supporting columns.

As an alternative to the percentages given in Table 4-2 of this report, live load reduction for columns,

piers, and walls are permitted to be taken as 15 percent of the live load on the top floor, increased at the

rate of 5 percent on each successive lower floor, with a maximum reduction of 50 percent. For girders

supporting 200 ft' or more of floor area, the allowable live load reduction is 15 percent.

2001 New York City Building Code—Floor live load reduction provisions of the 1968 New York City

Building Code remained unchanged in the 2001 version of the Code.

NISTNCSTAR 1-1B. WTC Investigation 13
Chapter 4

New York State Building Code—Provisions are given in Section C304.2.1 (c, d) of the New York State Code.

(a) Uniformly distributed live loads on beams and girders supporting other than storage areas and motor

vehicle parking areas, when such member supports 150 ft" or more of roof or floor area per floor:

• DL < 25 psf, maximum reduction is 20 percent

• 25 psf < DL < 100 psf, maximum reduction is the least of

- 60%

- 0.08 % per ft"

. <^^xioo%

4.33(IL)

(b) For columns, girders supporting columns, bearing walls, and walls supporting 150 ft" or more of roof

or floor area per floor other than storage areas and parking areas:

Maximum reduction is 20 percent for the top three floors including the roof, increased successively at the

rate of 5 percent for each successive lower floor, with a maximum reduction of 50 percent.

Chicago Municipal Code—Provisions are given in Section 68-2.2 of the Chicago Municipal Code.

(a) Columns, walls, piers and foundations: Live load reduction may be taken as 15 percent of the live load

for the top floor, increased at the rate of 5 percent on each successive lower floor, with a maximum

reduction of 50 percent. This is the same as the alternative live load reduction by the New York City

Building Code.

(b) Live load reduction for beams, girders and trusses is reproduced in the following table.

Tributary Area (ft^) Maximum LL Reduction (%)

< 100 0 100-200 5 200-300 10 >300 15

(c) Alternatively to (a) and (b), when DL > LL, the LL specified in Section 68-2.1 of the Chicago

Municipal Code may be reduced by the ratio of the specified LL to the DL. The reduced LL must in no

case be less than 2/3 of the LL specified in Section 68-2.1.

For storage rooms, reduction must not exceed one-half of the percentage reduction provided above.

14 NISTNCSTAR 1-1 B, WTC Investigation
Loads

BOCA-BBC—Provisions are given in Section 721.0 of the BOCA-BBC.

(a) Live load < 100 psf, maximum reduction is the least of

• 60 %

• 0.08 % per ft"

. 1^^.100%

4.33(ZZ)

No reduction is permitted for areas of public assembly. Note that the above is the same as in the New

York State Building Code requirements for beams and girders supporting more than 25 psf of dead load.

(b) Live load > 100 psf. no reduction, except that LL on columns may be reduced 20 percent.

See Fig. 4-1 and Table 4—3 for comparisons of the permitted live load reductions. The New York City

Building Code does not permit live load reduction in calculating shear stresses at the heads of columns in

flat slab or flat plate construction.

Figure 4-1 . Reduced live load of various building codes for columns, walls, and piers.

Reduced Live Load

1968 and 2001 NYC

Building Codes (Alternative Method) / Chicago Municipal

Code

Roo •

l"noor

2"" floor

•

3'" floor

4" floor

5" floor

6'" floor

7'" floor •

8'" and

subsequent

floor below

100

1964 NY State

Building Code

80%

85% 80%

80% 80%

75% 75%

70% 70%

65% 65%

60% 60%

55% 55%

50% 50%

In addition to the above, New York

City Building Codes have live load

reduction provisions for columns

based on tributary area and DULL

ratio, as does BOCA-BBC (see Table 4-3 below).

NISTNCSTAR 1-1 B, WTC Investigation 15
Chapter 4

Table 4-3. Reduced live load of various buildincJ codes for beams and girders.

Contributary

Area (ft^)

1968 and 2001 NY

City Building Codes

1967 Chicago

Municipal Code 1964 NY State/1965 BOCA Codes

100 or less 100% 100% 100%

100-150 100% 95 % 100%

1J sn-''no — V7 V7 80-85 % !

i

\

\ Also

! depends

V on the

i DULL

\ ratio.

1

}

95 % 84-88 % i These values are determined as

\ the larger of

i • [100-0. 08x(tributary area)],

1 or

1 . 40%

\ The percentage values also

i must not be less than

1 ( )x 100, which

j 4.33L/.

1 is not reflected in the ranges

/ listed.

''OO-'iOO 80-85 % 90% 76-84 % :

300-450 60-75 % 85 % 64-76% !

450-600 50-70 % 85% 52-64 % ;

600 and more 40-65 % 85 % 40-52 % 1

4.8 WIND LOADS

7965 New York City Building Code—According to Sub-Article 904.0, Wind Loads, wind forces are computed in accordance with the New York City Building Code Reference Standard RS 9-5, Minimum

Design Wind Pressures. Wind is assumed to act froin any direction, and for continuous framing

(structural meinbers continuous over their supports - for example, beams having full moment connections

with coluinns), the effects of partial loading conditions are considered. Minimum design wind pressures

acting on vertical surfaces are contained in Table RS 9-5-1, which is reproduced here as Table A—A.

Table RS 9-5-2 of the 1968 New York City Building Code (reproduced here as Table 4-5) contains the design wind pressures nonnal to horizontal and inclined surfaces.

Table 4-4. Design wind pressures on vertical surfaces per the

1968 New York City Building Code (Table RS 9-5-1).

Height Zone

(ft above curb

level)

Minimum Design Wind Pressure on Vertical Surfaces

(psf of projected solid surface)

Structural Frame Glass Panels

0-50' 15 0-100 20 30

101-300 25 30

301-600 30 35 601-1000 35 40

Over 1000 40 40

a. Signs and similar constructions of shallow depth only.

16 NISTNCSTAR 1-1B, WTC Investigation
Loads

Table 4-5. Design wind pressures on horizontal and inclined surfaces per the

1968 New York City Building Code (Table RS 9-5-2).

Roof Slope Design Wind Pressure Normal to Surface

30 degrees or less Either pressure or suction equal to 40 % of the values in Table RS 9-5-1 over the entire roof area More than 30 degrees Windward slope: pressure equal to 60 % of the values in Table RS 9-5-1. Leeward slope: suction equal to 40 % of the values in Table RS 9-5-1.

For purposes of design, pressures on vertical, horizontal, and inclined surfaces of the building are to be

applied simultaneously.

For the design of wall elements other than glass panels (i.e., mullions, muntins, girts, panels, and other

wall elements including their fastenings), the design wind pressure, which includes allowances for gust,

acting normal to wall surfaces, is specified as 30 psf pressure or as 20 psf suction for all heights up to 500 ft. Applicable design pressures for heights over 500 ft are to be determined from a special

investigation, but are not allowed to be less than those pressures indicated in Table RS 9-5-1. Minimum design wind pressures are also given for other building elements by multiplying the pressures

in Table RS 9-5-1 by the appropriate shape factors in Table RS 9-5-3. The shape factors vary from

0.7 degrees for upright, circular cylindrical surfaces to 2.0 for signs with less than 70 percent solid surface.

In lieu of the wind pressures mentioned above, design wind pressures may be detennined by "suitably

conducted model tests," subject to review and approval of the building commissioner. The tests are to be

based on a basic (fastest-mile) wind velocity of 80 mph at 30 ft above ground, and are to simulate and

include all factors involved in consideration of wind pressure, including pressure and suction effects,

shape factors, functional effects, gusts, and internal pressures and suctions.

2001 \ew York City Building Code—The wind provisions of the 1968 Code remained unchanged in the 2001 version of the New York City Building Code.

New York State Building Code—Minimum wind loads on walls (as well as eaves, cornices, towers,

masts, and chimneys) are given in Table C304-4a of the New York Sate Code (shown in Annex B3 of this report) and are compared with the New York City Building Code requirements in Fig. 4-2 of this report.

Figure 4-3 provides details of the New York State Building Code requirements. Wind loads on roofs are given in Table 304-4b (in Annex B3 of this). Detailed provisions are summarized in Table 7-2 of this report. There are no provisions on the use of model tests to establish the design wind pressures.

NISTNCSTAR 1-1 B. WTC Investigation 17
Chapter 4

025

psf/ft

ft

level

47.5

Increase

0.

above

100 «

•aoo

<

o

o

m

0) o

o

o

O)n

oo

<o

o _o

CM >

in —

0) o

CO

CO 0]

0) >

h; o

"1"

»a

oo

(/) 0) T3O

U

G)

io"5

(A3

O

>

"D

<U "5

cr

0)

1-

(A

0)U

(Q t:

15ur

>

c

o

(/)

(0o

"DC

E

E

CM

•DC

CM

I

0)3

il 3m

18 NISTNCSTAR 1-1B, WTC Investigation
Loads

1200 ft

1000 ft

800 ft

600 ft

300 ft

100 ft

Ground Level

200

200

200

100

100

100

100

100

40

20-

15

10 = 15'

37

36

35

Increase 1 psf/200 ft above 600 ft level

34

33

32

30

28

Tn

24

21

15 12 Figure 4-3. Minimum wind load (psf) as a function of height (ft) on vertical surfaces

required by 1964 New York State Building Code.

NISTNCSTAR 1-1B. WTC Investigation 19
Chapter 4

Chicago Municipal Code—Minimum design horizontal pressures are given in Table 68^.1 of the Chicago Municipal Code (see Annex B4 of this report), and are compared with the New York City

Building Code requirements in Fig. 4-2.

The Chicago Municipal Code states: roofs shall be designed for outward pressure equal to 75 percent of

those in Table 68^. 1 . Roofs with slopes greater than 30 degrees shall be designed for inward pressure equal to those in Table 68^.1. Overhanging eaves and cornices shall be designed and constructed for upward pressure equal to twice that in Table 68-4. 1 . There are no provisions on the use of model tests to establish the design wind pressures.

BOCA-BBC—Wind load on vertical surfaces is prescribed in Section 714.0 of the BOCA Code and is compared with the New York City Building Code requirements in Fig. 4-2. Wind on roof surfaces is prescribed in Section 715.0 of BOCA-BCCC (see Table 7-2 and Annex B5 of this report). There is a provision (Section 715.3) on the use of wind tunnel tests to detennine the effect of shape of irregular or unusual roofs, but there is no similar testing provision for wind pressures on vertical surfaces.

A comparison using the wind pressures from the aforementioned codes reveals that the largest shear force

at the base of a building the height of the WTC towers is obtained from the BOCA-BBC. Similarly, the

largest overturning moment at the base of a building the height of the WTC towers is also obtained from

the BOCA-BBC. The lowest base shear and moment are obtained from the 1968 and 2001 New York

City Codes. The base shear from the New York City Codes is approximately 20 percent less than that from the BOCA code, while the base moment is approximately 10 percent less (see Table 4-6).

Table 4-6. Base shears and overturning moments (per ft of building width) from

reviewed codes for a building the height of WTC towers (1,368 ft). 1968

NYC Code

2001

NYC Code

1964 NY State Code1967 Chicago

Municipal Code

1965 BOCABBC

Base shear (kip) 44.7 44.7 45.7 41.6 47.2 Overturning

monient{ft-kip) 33,778 33,778 33,474 33,143 37,707

4.9 EARTHQUAKE LOADS

1968 Neyv York City Building Code—There are no provisions for earthquake loads.

2001 New York City Building Code—This edition contains seismic design provisions from the 1988

edition of the Unifomi Building Code (ICBO 1988), including the 1990 Accumulative Supplement.

Significant modifications and amendments are made, however (see Exhibit RS 9-6 in Annex A2 of this report). The amendments include consideration of liquefiable soils, which is not included in the Uniform

Building Code.

New York State Building Code—The 1 964 edition of this Code has no provisions for earthquake loads.

Chicago Municipal Code—The 1967 edition of this Code has no provisions for earthquake loads.

BOCA-BBC—The 1965 edition of this Code contains provisions in Appendix K-1 1 that are adapted from

the 1962 edition of the Unifomi Building Code.

20 NISTNCSTAR 1-1B, WTC Investigation
Loads

4.10 SNOW LOADS

1968 and 2001 New York City Building Codes—The minimum roof load is specified to be 30 psf. The

value is such that it most likely includes snow loads.

New York State Building Code—Minimum snow loads must be determined from Table C304-3

(Annex B3 of this report) and the given snow map, and must be applied perpendicular to the roof surface. For a horizontal roof, a minimum 30 psf load must be used.

Chicago Municipal Code—A minimum of 25 psf roof live load nonnal to the roof surface, including snow loads, is specified for roofs having a pitch less than 30 degrees. Such live loads may be neglected

for roofs having a pitch of 30 degrees or more. However, wind pressures deteraiined in accordance with

Section 68-4.3 must be considered in the latter case. A minimum of 60 psf live load is required for roofs used for terraces, promenades, and similar structures.

BOCA-BBC—Minimum snow load on the roof in snow areas is 30 psf When the effect of the shape of

the roof as determined by actual tests indicates less or greater snow retention than specified in the code,

the roof load shall be modified accordingly. Special snow loads as indicated by the average snow depth

in the records of the U.S. Weather Bureau must also be considered.

The 1968 and 2001 editions of the New York City Building Codes require that foundation walls and

retaining walls be designed to resist, in addition to the vertical loads acting on them, the incident lateral earth pressures and surcharges, plus hydrostatic pressures corresponding to the maximum probable

ground water level. The three other codes have similar provisions (see Table 7-2 for comparison).

1968 and 2001 New York City Building Codes—Comprehensive provisions for construction loads are provided in Article 19 (1968 Code) or Subchapter 19 (2001 Code), Safety of Public and Property during

Construction Operations. Topics covered include general provisions, provisions for maintenance of site and adjacent areas, for protection of adjoining property, for excavation operations, for erection operations,

for demolition operations, for repair and alteration operations, for scaffolds, for structural ramps,

runways, and platforms, for material, handling and hoisting equipment, for explosive powered and

projectile tools, for explosives and blasting, and for flammable and combustible mixtures, compressed

gases, and other hazardous materials.

New York State Building Code—All flooring, structural members, walls, bracing, scaffolding, sidewalk

sheds or bridges, hoists and temporary supports of any kind incidental to the erection, aheration or repair

of any building shall be of such strength as to suffer no structural damage when subject to the temporary

loads and wind loads imposed during construction.

Chicago Municipal Code—There are no requirements related to construction loads.

BOCA-BBC—Provisions must be made for resisting temporary construction and wind loads that may

occur during the erection of the building.

NIST NCSTAR 1-1B. WTC Investigation 2

4.11 SOIL AND HYDROSTATIC PRESSURE

4.12 CONSTRUCTION LOADS
Chapter 4

4.13 FLUID PRESSURES

Only the New York City Building Codes have provisions related to fluid pressure. The design of building

components must consider pressures, both positive and negative, of confined fluids and gases.

4.14 ICE LOADS

Only the New York City Building Codes have provisions related to ice loads. The weight of 1/2 in. radial thickness of ice on all surfaces must be considered as part of the live load in the design of open framed or guyed towers.

4.15 THERMAL FORCES

Only the New York City Building Codes have provisions on thennally induced forces. Enclosed

buildings more than 250 ft in plan dimension shall be designed for 40 "^F temperature change. Exterior

exposed structures regardless of plan dimensions must be designed for 40 °¥ temperature change for concrete and masonry construction and 60 °F for metal construction. Provisions for piping are also given.

4.16 SHRINKAGE

Only the New York City Building Codes have provisions on the effects of shrinkage of concrete

structures. Reinforced concrete components must be designed for shrinkage defonnation of 0.0002

(nonnal-weight concrete) or 0.0003 (lightweight concrete) times the length between contraction joints.

4.17 DISTRIBUTION OF VERTICAL AND HORIZONTAL LOADS

Only the New York City Building Codes have provisions related to distribution of loads vertically along

the structure and horizontally to various resisting elements.

Vertical Load Distribution—Distribution of vertical loads to supporting members must be detennined on

the basis of a recognized method of elastic analysis or "system of coefficients of approximation." Elastic or inelastic displacements of supports shall be considered and, for the distribution of dead loads, the modulus of elasticity of concrete or composite sections shall be reduced to consider plastic flow.

Secondary effects, due to warping of the floors, must be considered.

Horizontal Load Distribution—Provisions are given for distribution of horizontal loads to vertical frames, trusses and shear walls, which must be based on relative rigidity; and for distribution of horizontal

loads within rigid frames of tier buildings, which can be based on elastic analysis, or given simplified

assumptions if certain limitations are satisfied, such as requiring approval of simplifying assumptions for buildings over 300 ft in height (see 906.2 for 1 968 Code in Table 7-2).

22 NISTNCSTAR 1-1 B, WTC Investigation
Chapter 5

Structural Work

"Structural work" is a tenn used in the New York City Building Codes and not in the other codes. The

scope of "structural work" includes, but is not limited to, materials and methods of construction; design

methods, including design load combinations; and the materials of construction, including concrete,

masonry, steel, and wood. Table 7-3 compares code provisions related to these topics.

5.1 STANDARDS

1968 New York City Building Code—The design standards adopted by this code are listed in Annex Al

of this report. The primary references of interest are the 1963 edition of ACl 318, Building Code

Requirements for Reinforced Concrete, and AISC 1963, Specifications for the Design, Fabrication and

Erection ofStructural Steel for Buildings.

2001 New York City Building Code—The design standards adopted by reference in this code are listed in Annex A2 of this report. The primary references are: the 1989 edition of the AC! 318, Building Code

Requirements for Reinforced Concrete, AISC 1989, Specifications for Structural Steel Buildings - ASD

and Plastic Design, and AISC-LRPD 1 993, Load and Residence Factor Design Specifications for

Structural Steel Buildings.

New York State Building Code—This code is a performance code, and does not adopt any standards by

reference. However, the State Building Code Council of the State of New York publishes a list of

Generally Accepted Standards that are listed in Annex A3 of this report. The list includes the 1963

edition of ACI 3 1 8, Building Code Requirements for Reinforced Concrete, and the 1963 edition of AISC,

Specifications for the Design, Fabrication and Erection ofStructural Steel for Buildings. The State Building Code Council also publishes a Code Manual to help the user implement the State Building

Construction Code. This Manual references standards that are deemed to comply with the requirements

of the code.

Chicago Municipal Code—The standards referenced by this code are listed in Annex A 4 of this report.

The primary references are the 1963 edition of ACI 318, Building Code Requirements for Reinforced

Concrete, and AISC 1963, Specification for the Design, Fabrication and Erection ofStructural Steelfor

Buildings.

BOCA-BBC—The adopted standards are listed in the appendixes to the BOCA-BBC (see Annex A5 of

this report). The referenced design standards for steel and concrete are the same as in the 1968 New York

City Building Code and the Chicago Municipal Code.

5.2 ALTERATION OF EXISTING BUILDINGS

796* and 2001 New York City Building Codes—Requirements for alterations are based on the cost of an

alteration as a percentage of building value. Whether the altered building or the alternations only need to

NISTNCSTAR 1-1B. WTC Investigation 23
Chapter 5

comply with the requirements of the Code depends on the cost of alterations versus the value of the building. When the cost of alterations relative to the value of building is low, the alterations may not have to be in compliance with the current Code "provided the general safety and public welfare are not thereby endangered."

New York State Building Code—It is required that any addition or alteration regardless of building value

must be made in conformity with the Code. The New York State Code is silent on the requirements for the remainder of the structure being altered.

Chicago Municipal Code—The provisions are similar to those of the New York City Codes.

BOCA-BBC—The provisions are similar to those of the New York City Codes.

5.3 MATERIALS AND METHODS OF CONSTRUCTION

1968 and 2001 New York City Building Codes—These codes prescribe testing and inspection

requirements for materials, assemblies, fonns, and methods of construction. The other three codes make

a distinction between "controlled" and "ordinary" materials, "ordinaiy" materials being those that are not

"controlled." Materials, assemblies, frames and methods of construction pennitted by the New York City

Building Codes would fall under the classification of "controlled materials" by the other codes.

New York State Building Code—According to this Code, "controlled materials" are those that have been

identified and certified for quality and strength by a recognized authoritative inspection service, grading

organization or testing laboratory, or are identified by manufacturer, producer, and mill test as meeting

generally accepted standards (Section C303-2 of the Code).

Chicago Municipal Code—According to this Code, "controlled materials" refers to a building, structure, or part thereof, which has been designed or constructed under the following conditions (Section 69-3.1 of

the Code):

• All materials must be selected or tested to meet the special strength, durability and fire resistance requirements upon which the design is based.

• The design, preparation of working drawings, including details and connections, the checking

and approval of all shop and field details and the inspection of the work during construction

must be under the supervision of a registered architect or structural engineer.

BOCA-BBC—According to BOCA-BBC Section 701.0, "controlled materials" are materials that are

certified by an accredited authoritative agency as meeting accepted engineering standards for quality.

24 NISTNCSTAR 1-1 B, WTC Investigation
Structural Work

5.4 USED AND UNIDENTIFIED MATERIALS

1968 and 2001 New York City Building Codes—Used materials and unidentified or ungraded materials

must be limited to nonstructural elements except for the following three conditions (see Sec. C26. 1000.9

in the 1968 Code):

• The elements or materials will be subject to stress levels that were experienced in previous

construction. In lieu of this, the load test procedures in Section C26. 1002.4 may be used to determine the load capacity of the materials or elements.

• Unidentified materials may be graded by the recovery and test of representative samples, or by other means satisfactory to the building commissioner.

• Used materials are considered to be graded when the grade is clearly indicated on the

approved plans for the existing construction. In such cases, allowable stresses are permitted

to be taken equal to those for that grade of like materials that were required at the time of

existing construction.

New York State Building Code—No provisions are included.

Chicago Municipal Code—Used materials are permitted to be used as long as they meet the minimum

requirements for new materials and all other special requirements of the Code.

BOCA-BBC—Similar to the Chicago Municipal Code, used materials are pennitted as long as they meet

the minimum requirements of the Code for new materials.

Each of the five codes reviewed permits designs that do not conform to the specific code, yet can provide

performance equivalent or superior to that required by the respective code.

Only the New York City Building Codes contain a provision (1968 Section C26-1001.1; 2001

Section 27-591 ) requiring that a building, or any element thereof, be proportioned to provide a minimum

factor of safety of 1 .50 against failure by shding or overturning. The required stability must be provided

solely by the dead load plus any permanent anchorage provided.

Only the New York City Building Codes (1968 Section C26-1001.2; 2001 Section 27-592) specifically

require that members used to brace compression members be proportioned to resist an axial load of at

least 2 percent of the total compressive design stress in the member braced, plus any transverse shear

therein.

5.5 EQUIVALENT SYSTEMS OF DESIGN

5.6 STABILITY

5.7 BRACING

NISTNCSTAR 1-1 B. WTC Investigation 25
Chapter 5

5.8 SECONDARY STRESSES

Only the New York City Building Codes (1968 Section C26-1001.3; 2001 Section 27-593) explicitly

require that secondary stresses in trusses be considered and, where of significant magnitude, their effects provided for in design.

5.9 LOAD COMBINATIONS

5.9.1 Allowable Stress Design

The following discussion on the load combinations for allowable stress design is applicable in the design

of structural steel (as well as masonry or wood) members in buildings.

1968 New York City Building Code—The following is a list of all possible load combinations that are specified in Section C26. 100 1.4:

1. D + L + RL

2. 0.15{D + (WoxSHoxToxUL)]

3. {).15[D + L + RL + {W ox SH or T or VL)]

4. {[Dor {D + L + RL)] + 0}

where:

D = effects of dead load (basic load)

L = effects of live load (basic load)

RL = effects of reduced Hve load (basic load)

JV — effects of wind load (load of infrequent occurrence)

SH = effects of shrinkage (load of infrequent occurrence)

T = effects of thermal forces (load of infrequent occurrence)

UL = effects of unreduced live loads where Hve load reduction is pennitted by

Article 9 (load of infrequent occurrence)

Q = the combination of any two or more of W, T, SH, and UL

2001 New York City Building Code—The load combinations for allowable stress design are the same as

for the 1968 New York City Building Code, except that the effects from earthquake forces {£) are included as loads of infrequent occurrence.

26 NISTNCSTAR 1-1 B, WTC Investigation
structural Work

New York State Building Code—When the stress due to wind is less than one-third of the stress due to dead load plus imposed loads excluding wind loads (live, snow, soil pressure including surcharge,

hydrostatic head, and impact), the stress due to wind may be ignored. However, when the stress due to wind exceeds one-third of the stress due to dead load plus imposed loads excluding wind, the allowable

stress of the material may be increased by one-third. Thus, the New York State Building Code

accommodates loads of infrequent occurrence by permitting higher stresses.

Chicago Municipal Code—For combined stresses due to dead, live (including snow), and wind loads, the allowable stresses may be increased by one-third, provided the section thus detennined can resist at least the stresses due to dead and live loads alone.

BOCA-BBC—The provision for allowable stresses due to dead, live, snow, and wind is the same as that

in the Chicago Municipal Code. Additionally, BOCA-BBC also allows a one-third increase in the allowable stress when the effects of earthquake forces are combined with the effects of dead, live, and snow loads.

5.9.2 Ultimate Strength Design

This section on load combinations for ultimate strength design is applicable to the design of reinforced concrete members in buildings. At the time of the design of the WTC towers, steel members were

designed by the allowable stress method only.

The 1968 New York City Building Code, the Chicago Municipal Code, and the BOCA-BBC reference

the 1 963 edition of the ACl 3 1 8, Building Code Requirements for Reinforced Concrete, for the design of

reinforced concrete structural members. The New York State Building Code, as has been mentioned

previously, is a performance code and does not adopt standards by reference. The following load

combinations are specified in ACl 318-63:

1. 1.5D^1.8I

2. \.25[D + L + (WorE)]

3. 0.9D+l.]{WorE)

The effects of SH or T are to be considered on the same basis as the effects of D (the same load factor should be applied to SH or Tas is applicable to D in a particular load combination).

The strength reduction factors corresponding to the above load combinations are 0.90 for flexure; 0.85 for diagonal tension, bond, and anchorage; 0.75 for spirally reinforced compression members; and 0.70 for

tied compression members.

The strength design load combinations of ACl 3 1 8-89, adopted into the 2001 New York City Building

Code, are:

1. \AD+\JL

2. 0.75[1.4Z)+ 1.71 + 1.7(^^^or I.IFI]

NISTNCSTAR 1-1B. WTC Investigation 27
Chapter 5

3. 0.9D+ 1.3(^f or 1.1£)

4a. \.4D+ IJL+ \JH>\ AD + \.7L

4h. 0.9D+ \.1H> IAD + \JL

5a. \AD+ \JL+ \AF>\AD+ \JL

5h. 0.9D+ \.4F>\.4D+ ].7L

{F = effects of weight and pressures of fluids with well-known densities and controllable maximum heights.)

6. 0.75 (1.4D+ 1.4r+ 1.71) > 1.4 (D +

If resistance to impact effects is taken into account in design, such effects shall be included with

live load L.

The strength reduction factors, to go with the above load combinations, are as follows:

• Flexure, without axial load 0.90

• Axial tension, and axial tension with flexure 0.90

• Axial compression, and axial compression with flexure:

- Members with spiral reinforcement 0.75

- Other reinforced members 0.70

Except that for low values of axial compression, ^may be increased gradually to 0.90.

• Shear and tension 0.85

• Bearing on concrete 0.70

There are modifications of the strength reduction factor for regions of high seismic risk.

5.10 DEFLECTION LIMITATIONS

All five codes contain similar limits on vertical deflections of floor and roof assemblies.

1968 and 2001 New York City Building Codes—The relevant provisions of several reference standards

cited in the Article (1968 Code) or Subchapter (2001 Code) on Structural Work apply. In addition, the

total of the dead plus live load vertical deflections (including effects of creep and shrinkage) of members

supporting walls, veneered walls, or partitions constructed of or containing panels of masonry, glass, or other frangible materials must not exceed 1/360 of the span.

28 NISTNCSTAR 1-1B, WTC Investigation
Structural Work

Nnv York State Building Code—Under imposed load, the deflection must not exceed 1/360 of the span

when the inside is to include plastered partition walls, and 1/240 of the span if it does not. When a roof is not to be used as a promenade, and the underside is not to be plastered, the deflection must not exceed

1/180 of the span.

Chicago Municipal Code—Under design live load, the deflection must not be greater than 1/360 of the span for plastered construction or 1/240 of the span for unplastered construction.

BOCA-BBC—The deflection of floor and roof assemblies must not be greater than 1/360 of the span for plastered construction; 1/240 of the span for unplastered floor construction; and 1/180 of the span for unplastered roof construction.

5.11 LOAD TESTS/CORE TESTS

Load tests and tests of in-situ concrete are carried out for various purposes, as enumerated in the New

York Cir>' Building Codes.

1968 and 2001 New York City Building Codes—These Codes have provisions for: (1) load tests carried out to verify adequacy of structural design for a member or an assembly, (2) load tests carried out to verify adequacy of questionable construction. (3) core tests to verify adequacy of concrete,

(4) prequalif> ing load tests for structural members before they are incorporated into structure, and

(5) load tests of completed construction to verify its strength and compliance with deflection limitations.

New York State Building Code—Provisions are included for (1) and (5) above.

Chicago Municipal Code—Provisions are found for (1), (3), and (5) above.

BOCA-BBC—Provisions are included for ( 1 ) and (2) above.

5.12 EXTERIOR WALL MATERIALS

Only the New York State Building Code and the BOCA-BBC have specific provisions related to exterior wall materials. These are required to be weather-resistant and durable.

5.13 PREFABRICATED CONSTRUCTION

Only the Chicago Municipal Code and the BOCA-BBC have provisions concerning prefabricated

construction.

5.14 MASONRY CONSTRUCTION

1968 and 2001 New York City Building Codes—Requirements for unreinforced masonry design and

construction are given in Reference Standard 10-1 (Annex Al of this report). American Standard

Building Code Requirements for Masonry, USASI A-41 .4, 1 960, is adopted as Reference

Standard 10-2 for reinforced masonry design and construction in the 1968 New York City Building

Code. ACI 530-92/ASCE 5-92 Building Code Requirements for Masowy Structures and

NISTNCSTAR 1-1B, WTC Investigation 29
Chapter 5

ACI 530.1-92/ASCE 6-92 Specificationfor Masoivy Structures are adopted as Reference Standard 10-2

for reinforced masonry design and construction in the 2001 edition of the New York City Building Code.

New York State Building Code—This code contains a general statement requiring that all structural units of natural or manufactured materials must comply with applicable specifications of authoritative agencies,

or must be subjected to test in conformity with generally accepted standards in order to detennine their characteristics.

Chicago Municipal Code—The 1954 edition of the American Standard Building Code Requirements for

Masonry, USASI A-41.4, is adopted by reference. Provisions for allowable stresses for grouted brick

masonry and for reinforcement and allowable stresses for reinforced brick masonry are also given.

BOCA-BBC—Specific provisions for various masonry elements are given.

5.15 CONCRETE

1968 New York City Building Code—ACI 318-63 is adopted to regulate concrete materials, design and

construction. ACI 525-1963, Minimum Requirementsfor Thin-Section Precast Concrete Construction, is adopted to regulate precast concrete construction "utilizing a thin skin or slab stiffened or supported by a system of ribs." In both cases, modifications are made. In addition, the 1968 New York City Building

Code has provisions on:

• Identification of metal reinforcement;

• Concrete mixtures (concrete may be proportioned, batched, and mixed by Method I, which

stipulates a minimum cement content, or Method II, performance concrete);

• Documentation;

• On-site inspection;

• Admixtures;

• Licensed concrete testing laboratories;

• Short-span concrete floor and roof construction supported on steel beams;

• Pneumatically placed concrete (shotcrete);

• Fomiwork; and

• Preplaced-aggregate concrete.

2001 New York City Building Code—ACI 3 1 8-89 has been adopted to regulate concrete materials,

design and construction. ACI 318-89 as well as MNL-120 1985, PCI Design Handbook, Third Edition,

has been adopted to regulate precast concrete construction. In both cases modifications have been made.

Additional provisions are included on the same topics as in the 1968 Code. In many cases, these

provisions have been updated, as detailed in Table 7-3 of this report. For instance, in mix design

30 NISTNCSTAR 1-1B, WTC Investigation
Structural Work

Method I, "cement factor ' has been replaced by "cement content." Mix design Method 11, Perfomiance

concrete, has been changed to "Proportioning on the basis of field experience."

New York State Building Code—This Code contains a general statement requiring that all structural units

of natural or manufactured material must comply with applicable specifications of authoritative agencies,

or must be subjected to test in conformity with generally accepted standards in order to detennine their characteristics.

Chicago Municipal Code—The design and construction of reinforced concrete is required to be in accordance with ACI 318-63. Detailed provisions for steel-concrete composite beams are given.

BOCA-BBC—The following documents are adopted for reinforced (including precast) concrete design

and construction: ( 1 ) ACI 711 1 958, Minimum Standard Requirements for Precast Concrete Floor and

Roof Units, (2) ASA (American Standards Association) A59.1 1954, Specificationsfor Reinforced

Gypsum Concrete, (3) ACI 318 1963, Building Code Requirements for Reinforced Concrete, (4) ACI 315

1 965, Manual ofStandard Practice for Detailing Reinforced Concrete Structures, (5) AWS D 1 2. 1 1 96 1

,

Recommended Practicesfor Welding Steel, Metal Inserts and Connections in Reinforced Concrete

Construction. In addition, a number of material standards are adopted in Appendix C (Annex A5 of this report).

The Code has provisions on Concrete Aggregates (817.0), Ready-Mix Concrete (818.0), Reinforcing

Steel (830.0), Reinforced Concrete (842.0), Controlled Concrete (843.0), Ordinary Concrete (844.), Structural Cinder (lightweight) Concrete (845.0), Short Span Floor Filling (846.0), Concrete-Filled Pipe

Columns 9847.0), Pneumatic Concrete (848.0), Minimum Concrete Dimensions (849.0), and Reinforced

Gypsum Concrete (850.0).

5.16 STEEL

1968 Mew York City- Building Code—Materials, design, and construction methods must meet the requirements of:

• AISC 1963, Specifications for the Design, Fabrication and Erection ofStructural Steelfor

Buildings

• AISI 1962, Specification for the Design ofLight Gage Cold-Formed Steel Structural

Members

• AISI/SJI July 1 , 1 966, Standard Specifications and Load Tablesfor Long Span Steel Joists,

LJ-Series and LH-Series

• AISI/SJI February, 1965, Standard Specifications and Load Tables for Open Web Steel

Joists, J-Series and H-Series

In each case, modifications are made. In addition, there are specific identification (i.e., marks on steel)

and quality control requirements.

NISTNCSTAR 1-1 B, WTC Investigation 31
Chapter 5

2001 New York City Building Code—Materials, design and construction methods must meet the requirements of:

• AISC 1989, Specification for Structural Steel Buildings - Allowable Stress Design and Plastic

Design

• AISC-LRFD 1 993, Load and Resistance Factor Design Specification for Structural Steel Buildings

• Unifonn Building Code 1988, including 1990 Accumulative Supplement, Section 2723, Steel Structures Resisting Forces Induced by Earthquake Motions in Seismic Zones No. 1 and 2.

• AlSl 1 986, Specification for the Design of Cold Formed Stainless Steel Structural Members

• AlSl 1 974, Specification for the Design of Cold-Formed Steel Structural Members

• SJI 1978, Revised 1983, Standard Specifications for Open Web Steel Joist, H-Series

• SJI 1985, Revised 1987, Standard Specifications for Open Web Steel Joists, K-Series

• SJI 1978, Revised 1987. Standard Specifcations for Longspan Steel Joists, LH-Series and

Deep Longspan Steel Joists, DLJH-Series

• SJI 1078, Revised 1987, Standard Specifications for Joist Girders

• SJI 1988, Standard Specifications, Load Tables and Weight Tables for Steel Joists and Joist

Girders

Modifications are made to each of the above standards.

New York State Building Code—This Code is a perfomiance code. It contains a general statement

requiring that all structural units of natural or manufactured materials must comply with applicable

specifications of authoritative agencies, or must be subjected to test in confonnity with generally accepted

standards in order to detennine their characteristics.

Chicago Municipal Code—The following standards are adopted by reference:

• AISC 1963, Specifcations for the Design, Fabrication and Erection ofstructural Steel for

Buildings

• AISI 1962, Light Gage Cold-Formed Steel Design Manual

• SJI 1963, Open Web Joist - Standard Specifcations and Load Tables

There are also provisions for cast iron, cast steel, and special steels.

32 NISTNCSTAR 1-1 B, WTC Investigation
structural Work

BOCA-BBC—The following standards are adopted:

• AISC 1963, Specifications for the Design. Fabrication and Erection ofstructural Steelfor

Buildings

• AISC 1 960, Specificationsfor Architectural Exposed Structural Steel

• AISC 1 964, Specifications for Structural Joints using ASTMA325 or A490 Bolts

• AlSl 1962, Light Gage Cold-Formed Steel Design Manual

• AlSl 1 962, Specifications for Light Gage Cold-Formed Steel Structural Members

• AISC-SJI 1961, Standard Specifications for Open Web Steel Joists. Longspan or LA-Series

• SJl- AISC 1965, Specifications and Load Tables for Open Web Steel Joists, J-Series and

H-Series

• SJI-AISC 1962. Standard Specifications for open Web Steel Joists. Longspan or LH-Series

There are also provisions for cast steel construction, cast iron construction, special steels, lightweight

metal alloys, alloy, and special steel.

5.17 WOOD

1968 Sew York City Building Code—Materials (other than non-stress graded lumber), design and

construction methods must meet the requirements of the following:

• Lumber and Timber - NLMA (National Lumber Manufactures Association) 1 962, National

Design Specification for Stress-Graded Lumber and its Fastenings

• Plywood - Specifications are given as part of the code itself in Reference Standard 10-9

(Annex Al of this report)

• Structural glued-laminated lumber - U.S. Department of Commerce CS 253-1963,

U.S. Commercial Standardfor Structural Glued Laminated Lumber

Modifications are made to the NLMA and U.S. Department of Commerce standards.' In addition, there

are provisions on: identification, use of non-stress graded wood, quality control, general construction

requirements, empirical provisions in lieu of design, heavy timber construction, and construction

methods.

U.S. Department of Commerce (DOC) Voluntary Product Standards are developed by U.S. industry and published by DOC

following Procedures for the Development of Vohmtaiy Product Standards contained in Title 1 5 Code of Federal Regulations

Part 10. The National Institute of Standards and Technology administers this program, on behalf of the DOC, on a fee for service basis.

NISTNCSTAR 1-1B. WTC Investigation 33
Chapter 5

2001 New York City Building Code—Materials (other than non-stress graded lumber), design, and

construction methods must meet the requirements of;

• Lumber and Timber - AF&PA (American Forest and Paper Association) 1991, National

Design Specification for Wood Construction and its 1991 Supplement with 1993 Revisions

• Plywood - Specifications are given as part of the code itself in Reference Standard 10-9

(Annex A2 of this report)

• Structural glued-laminated lumber - ANSI/AITC (American Institute of Timber

Construction) A 190.1 1992, Structural Glued Laminated Timber and AITC 200-92

Inspection Manual

- AITC 1 17 1987, Specification for Structural Glued Laminated Timber ofSoftwood

Species -Design Standard

— AITC 117 \9%'&, Specification for Structural Glued Laminated Timber for Softwood

Species - Construction Standard

Modifications are made to the AF&PA Standard. In addition, there are provisions on the same items as in the 1968 code.

New York State Building Code—This is a performance code. It contains a general statement requiring

that all structural units of natural or manufactured materials must comply with applicable specifications of

authoritative agencies, or must be subjected to test in conformity with generally accepted standards in order to determine their characteristics.

Chicago Municipal Code—NLMA - 1957 National Design Specifications for Stress-Graded Lumber and

its Fastenings is adopted by reference. In addition, maximum allowable unit stresses for lumber used as ordinary material (as opposed to controlled material) are given. Also given are provisions for bolted

joints and ventilation of enclosed wood construction.

BOCA-BBC—The following are adopted by reference:

• AITC-200 1 963, Inspection Manual for Structural Glued Laminated Lumber

• NLMA 1 962, National Design Specifications for Stress Graded Lumber and Its Fastenings

• ^LMA 1957, Wood Structural Design Data

• AlTC-lOO 1962, Timber Construction Standards

• USDA Handhook'No. 12 \955, Wood Handbook

In addition, a number of American Plywood Association ( APA, formerly DFPA, or Douglas Fir Plywood

Association) standards are adopted.

34 NISTNCSTAR 1-1B, WTC Investigation
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There are detailed provisions for Lumber and Timber Construction (853.0), Heavy Timber Type

Construction (854.0), Wood Frame Construction (855.0), Stress Skin Panels (856.0), and Glued

Laminated and Built-Up Lumber Construction (857.0).

5.18 ALUMINUM

The 1968 New York City Building Code adopted ASCE-1963 Suggested Specifications for Structures of

Aluminum Alloy. The 2001 New York City Building Code adopts:

• AA (Aluminum Association) SAS 30 1986, Specificationsfor Aluminum Structures, Fifth Edition

• ASTM B209 1988, Standard Specifcation for Aluminum and Aluminum-Alloy Sheet and

Plate

• ASTM B308 1988, Standard Specifcation for Aluminum -Alloy 6061-T6 Standard

Stinctural Shapes, Rolled or Extruded

• ASTM B429 1 988, Standard Specifcation for Aluminum -Alloy Extruded Structural Pipe

and Tube

In addition, there are specific requirements on identification, quality control, and erection.

The only other code with provisions for structural aluminum is the BOCA-BBC, which has adopted:

• AA 1963, Aluminum Construction Manual, Section A - Specifcations for Structures of

Aluminum Alloys

5.19 REINFORCED GYPSUM CONCRETE

Gypsum concrete is intended for use in the construction of poured-in-place roof decks or slabs.

1968 New York City Building Code—USASI A59.1-1954, American Standard Specifcation for

Reinforced Gypsum Concrete is adopted. Also contained are provision on identification of metal

reinforcement and limitation of use.

2001 i\ew York City Building Code—ASTM C 317-1976, Standard Specifcation for Gypsum Concrete

(Reapproved 1981) is adopted. Also included are provisions on identification of metal reinforcement and

limitation of use.

New York State Building Code—This is a performance code; thus, no specific standard is adopted by

reference.

Chicago Municipal Code—ASA (American Standards Association) A59.1-1954 (described as USASI

A59.1-1954 in the 1968 New York City Building Code) is adopted.

BOCA-BBC—Refers to the same standard as the Chicago Municipal Code.

NISTNCSTAR 1-1B, WTC Investigation 35
Chapter 5

5.20 THIN SHELL AND FOLDED PLATE CONSTRUCTION

Only the New York City Building Codes have specific provisions summarized in Table 7-3 of this report.

5.21 SUSPENDED STRUCTURES

Only the Nev^ York City Building Codes have specific provisions summarized in Table 7-3 of this report.

36 NISTNCSTAR 1-1 B, WTC Investigation
Chapter 6

Foundations

6.1 GENERAL REQUIREMENTS

1968 and 2001 I\'ew York City Building Codes—Foundations of buildings including retaining walls and

other structures are required to bear on, or be carried down to, satisfactory bearing materials in such a manner that the entire transmitted load will be distributed over the supporting soils at any depth beneath

the foundation at unit intensities within the allowable bearing values. In addition, foundations must be

proportioned to limit settlements to a magnitude that will not cause damage to the proposed construction or to existing adjacent or nearby buildings during and after construction. The New York City Building

Codes specifically adopt a number of American Wood-Preservers' Association and ASTM International

(ASTM) standards as Reference Standard RS 11 . The specified depth of foundation is below "the lowest

level of the adjoining ground or pavement surface that is exposed to frost."

New York State Building Code—Protection is required whenever structural material or assemblies are subject to deterioration from causes such as freezing and thawing and might become structurally unsound

if unprotected. Also required is prevention of ground and surface water penetrating into habitable spaces, basements and cellars. There is no requirement concerning depth of foundation.

Chicago Municipal Code—Encroachment of foundations on public property is discussed. The depth of

foundation must be below the adjoining ground surface.

BOCA-BBC—Foundations must have adequate strength to support the superimposed live and specified

loads in addition to their own dead load without exceeding the allowable stress specified in the Basic

Code or in accepted engineering standards. The Building Officials and Code Administrator (BOCA)

Basic Building Code (BBC) also requires: "Except when erected on rock or when otherwise protected

from frost, foundation walls, piers and other pennanent supports shall extend below the frost line....No

footings shall be founded on frozen soils unless such frozen condition is pennanent."

6.2 SOIL INVESTIGATIONS

796* and 2001 New York City Building Codes—Soil investigation (borings or test pits) is mandatory,

although certain exceptions are allowed. The New York City Codes have provisions concerning boring

methods and provisions for the use of probings, auger borings, or geophysical methods to substitute for borings. The other codes do not have similar provisions. The New York City Codes also allow existing

boring data to be used, provided certain specified conditions are met.

New York State Building Code—Soil investigation is mandatory for buildings in which the sum of snow

load and live loads of all floors that are transmitted by columns or walls to the soils, divided by gradefloor area, exceeds 200 psf.

Chicago Municipal Code—Where there is reasonable doubt as to the character and bearing capacity of

the soil, the building commissioner may require borings, test pits, or test loads.

NISTNCSTAR 1-1 B. WTO Investigation 37
Chapter 6

BOCA-BBC—Only one exploratory boring is mandatory for other than low-rise buildings or for deep

foundations "in the absence of satisfactoiy data from immediately adjacent areas."

6.3 FOUNDATION LOADS

1968 and 2001 New York City Building Codes—The loads to be used in computing the bearing pressures on materials directly underlying footings, and the loads to be used in computing pile reactions are clearly

set forth. Provisions are given for: (a) earth and ground water pressures, (b) wind and other

superstructure loads, and (c) soil movements. Provision for eccentricity of loading on foundations is given. Uplift and overturning forces due to wind and hydrostatic pressure are required to be considered.

Impact loads are allowed to be neglected except in certain specified cases.

New York State Building Code—Overturning and uplift forces due to wind or hydrostatic head are required to be considered, but no other provisions are included.

Chicago Municipal Code—No provisions concerning foundation loads are included.

BOCA-BBC—All retaining walls and other walls below grade are required to be designed to resist lateral

soil pressures with due allowance for hydrostatic pressures for all superimposed vertical loads. All

foundation slabs and other footings subjected to water pressure are also required to be designed to resist a uniformly distributed uplift equal to the full hydrostatic pressure.

6.4 ALLOWABLE SOIL BEARING PRESSURES

1968 and 2001 New York City Building Codes—Soils are classified in Code Table 1 1-1 (Annex Bl of

this report). Some soils are designated as satisfactory bearing materials, others are designated as nominally unsatisfactory bearing materials. The allowable bearing pressures on satisfactory bearing

materials are given in Code Table 1 1-2 (Annex Bl). Provisions are included for construction on

nominally satisfactory bearing materials. Provisions are also given to prevent damage to utility service

lines laid in soil materials.

New York State Building Code—The bearing value of soil is required to be detennined so that foundations are proportioned to provide a minimum of absolute and differential settlement. Soil or pile

tests, presumptive bearing values of the soil, reduction factors for pile groups, and pile driving formulas,

refeiTcd to in the code, must be in confonnity with generally accepted standards. When it can be proven

conclusively that the presumptive soil bearing value is adequate for the proposed load, the enforcement

officer may accept such proof in lieu of the bearing capacity determination

Chicago Municipal Code—Soils are classified into: solid rock, soft rock, boulders, gravel, sand,

inorganic silt, clay, hardpan, and organic soil. Maximum allowable pressures on the supporting soils at the bottom of footings are given in Code Table 70-2.4(a) (Annex B4 of this report).

BOCA-BBC—Presumptive surface bearing values of foundation materials are given in Table 15 (Annex B5 of this report). Except when determined by field loading tests or as otherwise provided in the code, the maximum allowable pressure on supporting soils under spread footings at or near the surface is required not to exceed the values specified in Table 15. Surface values of allowable bearing pressures may be adjusted for deep footings and for bearing under piles as provided for in the BOCA-BBC.

38 NISTNCSTAR 1-1B, WTC Investigation
Foundations

6.5 SOIL LOAD BEARING TESTS

1968 and 2001 New York City Building Codes—Soil load bearing tests may be accepted as evidence of

allowable bearing capacity of a given soil stratum, subject to a number of limitations, one of which is that such tests must not be used to justify allowable bearing pressures in excess of the maximum allowable

bearing \ alues in Code Table 1 1-2 (Annex Bl of this report). Provisions are given for preparation,

loading of the soil, and determination of bearing capacity.

New York State Building Code—Acceptance criteria for field loading soil tests are given.

Chicago Municipal Code—Whenever the bearing value of soil is in reasonable doubt or when it is desired to use soil-bearing values in excess of those established in Code Table 70-2.4(a) (Annex B4 of

this report), the allowable load on a bearing material may be determined by test in accordance with

requirements given in the Code.

BOCA-BBC—The maximum allowable pressure on supporting soils may be detennined by field loading

test. Test procedure and acceptance criteria are given.

6.6 FOOTINGS, FOUNDATION PIERS, AND FOUNDATION WALLS

1968 New York City Building Code—There are provisions concerning wood footings, wood and steel poles supporting buildings, foundation grillages, concrete footings that must confonn to ACI 3 1 8-63 and

masonry footings that must conform to USASI A-41.2 1960. The Code also has provisions concerning

foundation piers, which must be designed as columns, of unreinforced and reinforced concrete as well as unreinforced and reinforced masonry. Finally, there are provisions concerning concrete and masonry

foundation walls. Pro\ isions regulating construction of footings, foundation piers, and foundation walls

are also included.

2001 New York City Building Code—The same provisions as in the 1 968 Code are included, but the standards have been updated.

New York State Building Code—There are no specific provisions on footings, foundation piers, or foundation walls.

Chicago Municipal Code—There are provisions concerning concrete footings, which must be

constructed of solid masoru7 or concrete with or without reinforcement. There are provisions concerning

foundation columns, which must consist of steel pipe shells extending to rock and completely filled with

concrete with or without steel reinforcement or cores. There are provisions concerning foundation piers

and caissons, which must be of concrete with or without steel reinforcement, extending to solid rock or to hardpan.

BOCA-BBC—There are provisions concerning footing design, timber footing, steel grillages,

unreinforced concrete footings, masonry unit footings, reinforced concrete footings, and mat, raft and

float foundations. There are provisions concerning foundation piers—unreinforced, reinforced, and with

steel shells, and foundation walls.

NISTNCSTAR 1-1 B. WTC Investigation 39
Chapter 6

6.7 PILE FOUNDATIONS—GENERAL REQUIREMENTS

1968 and 2001 New York City Building Codes—Provisions are included concerning minimum pile

penetrations, use of existing piles at demolished structures, tolerances and modification of design due to

field conditions, minimum spacing of piles, minimum section, capping and bracing of piles, splicing of

piles, general requirements for installation of piles, use of uncased concrete pile shafts, use of more than one pile type, pile capacity, or method of pile installation and pile materials.

New York State Building Code—There are no specific provisions on any of the above.

Chicago Municipal Code—Provisions are included concerning minimum spacing of piles and pile caps.

BOCA-BBC—A building site must be investigated for all conditions that might promote deterioration of

pile foundations, and approved protective measures must be taken. The BOCA-BBC also contains

provisions concerning minimum length and penetration of piles, precautions (including tolerance to

lateral deviation from plumb), spacing of piles, minimum dimensions, piles in wall foundations, isolated

pier plies, splices, and corrosion protection.

6.8 PILE FOUNDATION—LOADS

1968 and 2001 New York Cit}' Building Codes—The allowable axial load on a pile must be the least value considering (a) the capacity of the pile as a structural member, (b) allowable bearing pressure on

soil strata underlying the pile tips, (c) capacity as indicated by resistance to penetration, (d) capacity as indicated by load test, and (e) maximum allowable loads - ( 1 ) Basic maximum load values are given in Code Table 1 1-6 (Annex Bl of this report); (2) Loads higher than the basic values can be substantiated on the basis of tests and analysis. Provisions for allowable lateral load are given. A minimum factor of

safety of two is required against withdrawal. The safety factor needs to be greater if the pile is subject to dynamic loading. If the safety factor is three or more, no pull-out test is required.

New York State Building Code—No specific provisions are included concerning allowable pile load.

Chicago Municipal Code and BOCA-BBC—Both codes have detailed provisions, summarized in Table 7^, which are similar to those in the New York City Building Codes.

6.9 PILE DRIVING OPERATIONS

The New York City Building Codes have provisions concerning equipment and procedures for pile

driving with the proviso that the provisions do not apply to piles driven with a vibration hammer or other

equipment wherein the energy of impact cannot be evaluated. The BOCA-BBC is the only other code

with provisions on pile driving operations, but regulates jetting only.

40 NISTNCSTAR 1-1B, WTC Investigation
Foundations

6.10 PILE TYPES -SPECIFIC REQUIREMENTS

1968 and 2001 New York City Building Codes—There are provisions concerning timber piles, precast concrete piles, cast-in-place concrete piles, compacted concrete piles (a concrete pile formed with an

enlarged base in which the concrete in the base is placed in small batches that are compacted prior to attaining an initial set), steel H piles, concrete filled pipe piles, caisson piles (concrete filled pipe piles that are socketed into bedrocks of certain classes and constructed with steel cores), and composite piles.

New York State Building Code—There are no specific provisions.

Chicago Municipal Code—There are provisions concerning timber piles, precast concrete piles, cast-in- place concrete piles, structural steel pipe piles, concrete-filled steel piles, and special type of piles,

including composite piles.

BOCA-BBC—This code contains provisions concerning timber piles, precast concrete piles, cast-in-place concrete piles, structural steel pipe piles, concrete-filled steel piles, drilled caissons, composite piles, as well as special piles and caissons.

6.11 UNDERPINNING

The New York City Codes are the only ones among the five codes reviewed to have specific provisions

concerning support of adjacent existing structures.

6.12 STABILITY

The New York City Building Codes specify minimum factors of safety against sliding and overturning.

There is no such explicit requirement in the other codes. (Section 5.6 of this report dealt with stability of

structural elements; this section deals with stability of foundation elements.)

6.13 INSPECTION

The New York City Building Codes specifically require inspection of the following: boring operation;

piling; footings, foundation piers, foundation walls and pile caps; subgrade for footing, foundation piers,

and foundation walls; construction required for or affecting the support of adjacent properties or

buildings. The other codes do not have any specific foundation inspection requirements.

NISTNCSTAR 1-1B. WTC Investigation 41
Chapter 6

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42 NISTNCSTAR 1-1B, WTC Investigation
Chapter 7

Detailed Comparison Tables

Tables have been prepared to provide detailed comparisons of the structural provisions of the five codes

that were reviewed. Comparisons of provisions concerning definitions, loads, structural work, and

foundations are given in Tables 7-1 through 1—^. as follows:

• Table 7-1, Definitions

• Table 7-2, Loads

• Table 7-3. Structural Work

• Table 7-4, Foundations

These tables can be found following Chapter 9 of this report. The tables include "comments" that summarize the comparisons.

NISTNCSTAR 1-1B, WTC Investigation 43
Chapter 7

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44 NISTNCSTAR 1-1 B, WTC Investigation
Chapter 8

Summary

The structural provisions of the New York City Building Code, 1968 edition, which were required by the Port Authority to be followed in the design of World Trade Center (WTC) 1 and WTC 2, are compared in

this report with the structural provisions of the 2001 edition, the edition currently in effect. Also

compared are the structural provisions of three other contemporaneous codes: the New York State Building Code, 1964 edition; the Municipal Code of Chicago, 1967 edition (Chicago was chosen as a major U.S. city with tall buildings, outside of the northeastern states); and the Building Officials and

Code Administrator (BOCA) Basic Building Code (BBC), 1965 edition (chosen as the model building

code typically adopted as the basis of local codes in the northeastern states).

With respect to structural design provisions, the major changes from the 1968 to the 2001 edition of the New York City Building Code are the inclusion of seismic design requirements and updating of

standards. Of the codes contemporaneous with the 1968 New York City Building Code, only the BOCA-BBC had seismic design requirements, which were adopted from the 1962 edition of the Uniform

Building Code (UBC). Taller buildings have longer periods of vibration, which means lower seismic

design forces. Also, since New York City is in an area of moderate seismicity (UBC Zone 2A),

additional seismic detailing requirements are minimal to nonexistent.

The alternate li\ e load reduction provisions for columns, walls, and piers of the 1968 and 2001 New York

City Building Codes are the same as in the Chicago Municipal Code; the New York State Building Code

has more liberal li\ e load reduction provisions for upper portions of buildings (see Fig. 4-1 of this report). The New York City Building Codes also have live load reduction provisions based on

contributory floor area and live-to-dead load ratio. For live-to-dead load ratios of 0.625 or less, the New

York City code provisions may yield higher live load reduction for columns, walls, and piers than

allowed by the other codes. For beams and girders, the live load reduction provisions of the New York

City Building Codes are comparable to those of the New York State Building Code and the BOCA-BBC.

The Chicago Municipal Code has more conservative requirements (see Table 4-2 of this report). The

maximum live load reduction allowed for beams and girders in the Chicago Municipal Code is 15 percent, compared with 40 percent in the other codes.

.Minimum wind loads on vertical surfaces required by the various building codes are compared in Fig. 4—2. The largest shear force at the base of a building is obtained from the BOCA-BBC when the height of the building is taken equal to 1,368 ft (i.e., the height of WTC 1). Similarly, the largest

overturning moment at the base of a building the height of the WTC towers is also obtained from the BOCA-BBC. Thus, the New York City Building Codes do not have the most stringent wind load

provisions. Base shear forces and overturning moments from the codes reviewed for a building the height

of WTC towers are compared in Table 4—6 of this report.

The primary materials design standards referenced by the 1968 New York City Building Code, the Chicago Municipal Code and the BOCA-BBC are the 1963 edition of ACI 318, Building Code

Requirements for Reinforced Concrete, and AISC 1963, Specificationsfor the Design, Fabrication and

NISTNCSTAR 1-1 B. WTC Investigation 45
Chapter 8

Erection ofStructural Steelfor Buildings. The New York State Building Code, being a perfoiTnance

code, does not adopt any specific standards by reference. The 2001 New York City Building Code adopts

the 1989 edition of ACI 318, AISC 1989, Specifications for Structural Steel Buildings -ASD and Plastic

Design, and AISC-LRFD 1993, Load and Resistance Factor Design Specifications for Structural Steel Buildings.

The New York City Building Codes have extensive and quite rigorous foundation design and construction

requirements. The foundation related provisions of the other codes are less extensive and typically less rigorous.

New York City Building Codes prescribe testing and inspection requirements for all materials,

assemblies, forms and methods of construction. The other three codes require that materials and methods

of construction meet the criteria of generally accepted standards. With respect to foundations, only the New York City Building Codes have specific requirements for foundation inspection.

46 NISTNCSTAR 1-1 B, WTC Investigation
Chapter 9

References

BCB (Building Code Bureau). 1964. State Building Construction Code Applicable to General Building

Construction. NY, December 1. BOCA (Building Officials Conference of America). 1965. BOCA Basic Building Code, Fourth Edition.

Chicago, IL.

The City of Chicago. 1967. Municipal Code of Chicago Relating to Buildings, As Amended to and

Including Januaiy 1, 1967. Index Publishing Corp., Chicago, IL.

TheCity ofNew York. 1968. The City ofNew York Building Code. NY.

The City of New York Committee on Buildings. 1968. Report to the Council, Report ofthe Committee

on Buildings Dated June 28, 1968 Which Favored the Adoption ofthe Building Code. NY.

The City of New York. 2001 . Building Code ofthe City ofNew York. Gould Publications. Binghamton,

NY.

ICBO. 1962. Uniform Building Code, International Conference of Building Officials, Whittier, CA

ICBO. 1988. Uniform Building Code, International Conference of Building Officials, Whittier, CA

The Office of Irw m G. Cantor. 1983. Structural Drawings for WTC 7 (WTCI-25-S, Disk 1 of 3). WTC 7 Project Specifications. 1984. (WTCI-187-P)

NISTNCSTAR 1-1 B. WTC Investigation 47
Chapter 9

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48 NISTNCSTAR 1-1B, WTC Investigation
Definitions

Table 7-1. Definitions.

NYC Building Code (1968) NYC Building Code (2001)

NY State Building Construction

Code (1964)

Article 2 Definitions CI 08 Abbreviations and Definitions

Sub-Article 200.0 General C108-1 General

200.1 .Application of terms 27-229 Same

200.2

Definitions in reference

standards 27-230 Same

200.3 Tense, gender, and number 27-231 Same

C108-2 Abbreviations

I I/O J LyLJ lltllttfll^

Accessor}' building Accessorv' Building Accessory structure

i^LLcbsUiv use /\cccssory use r\CLcssoiy use

Accessible

Accessible route Access Stair Adaptable dwelling units

.addition Addition Addition

Adjoinins 2rsde cle\ alion Adjoining grade elevation

Alley Allowable soil pressure Allowable stress

.Alteration Alteration Alteration

.Apartment house Apartment house Approved Approved

.Area of refuge Area of refuge

NISTNCSTAR 1-1 B, WTC Investigation 49
Table 7-1

Table 7-1. Definitions (continued).

Municipal Code of Chicago (1967)

BOCA Building Code - Basic Code

(1965) Comments

Article 2 Definitions and Classifications

200.0 Scope

200.1 Application of tenns

200.2 Application of other laws

201.1 Tense, Gender and number

201.2 Tenns not defined

Chapter 47 Definitions Definitions ABC

Accepted engineering practice Accepted engineering practice

Building, accessory Accessory structure Accessory use Accessory use

Addition Addition

Aisles, longitudinal

Aisles, transverse Alcove

Alley

Alteration Alteration Apartment building Apartment

Approved Approved

Appurtenant structure ABC

Accepted engineering practice Accepted engineering practice

Building, accessory Accessory structure

Appurtenant structure ABC

Accepted engineering practice Accepted engineering practice

Building, accessory Accessory structure Area (building) Area (floor surface measurement)

50 NISTNCSTAR 1-1B, WTC Investigation
Definitions

Table 7-1. Definitions (continued).

NYC Building Code (1968) NYC Building Code (2001)

NY State Building Construction

Code (1964)

Areaway Areaway

Assembly space Assembly space Assembly place

Attic Attic Attic

Balloon frame Balloon frame Basement Basement Basement

Bathroom

Bearing Bearing

Breezevvay Breezeway

Building Building Building

Building line

Building section Building section

Bulkhead Bulkhead

Cabaret

Casing-off Casing-off

Catch platform Catch platform

Cellar Cellar Cellar

Chimney Chimney

Chimney connector Chimney connector

Concentrated load Concentrated load

Concurrent loads Concurrent loads

Construction Construction

NISTNCSTAR 1-1 B, WTC Investigation 51
Table 7-1

Table 7-1. Definitions (continued).

Municipal Code of Chicago (1967)

BOCA Building Code - Basic Code

(1965) Comments

Areaway

Ashlar facing

Ashlar masonry Assembly unit

Attic Balcony

Basement Basement BBC

Bay

Bay window

Brick

Building Building

Building line

Building official

Building service equipment

Building site

Buttress

Cellar

Certificate of use and occupancy Change of use Chimney Chimney

Clay masonry unit

Concrete

Concrete masonry unit

52 NISTNCSTAR 1-1B, WTC Investigation
Definitions

Table 7-1. Definitions (continued).

NYC Building Code (1968) NYC Building Code (2001)

NY State Building Construction

Code (1964)

Construction class Construction class Construction classification

Construction fireproof Console lift Console lift

Contractor Contractor

Controlled inspection Controlled inspection

Con\ alescent home

Corridor Corridor Corridor

Court Court Court, inner

Court, inner, width

Cross aisle Cross aisle Curb level Dead load Dead load Load, dead

Demolition Demolition Dwelling Dwelling

Dwelling unit Dwelling unit Enforcement officer

Engineer Engineer

Equi\ alent uniform load Equi\alent uniform load

Existing building

Existing high rise building

Existing office building, >100 ft

Exit Exit Exit

Extenor separation Exterior separation

Exterior stair Exterior stair

Fallout shelter

Floor area Floor area Floor area

Floor area (net) Floor area (net) Folded plate Folded plate

Footing Footing

Foundation (building) Foundation (building)

Foundation pier Foundation pier

Foundation wall Foundation wall

Framework Framework

NISTNCSTAR 1-1B. WTC Investigation 53
Table 7-1

Table 7-1. Definitions (continued).

Municipal Code of Chicago (1967)

BOCA Building Code - Basic Code

(1965) Comments

Construction equipment

Construction operation

Controlled materials Controlled materials

Corridor

Court, inner Court

Curb level

Dwellings

Dwelling unit Dwelling unit

Building, existing Existing building

Exit Exitways

Exterior masonry wall construction

Concrete masonry unit

Floor area

Formed steel

Foundation

Foyer Foyer Frame construction

54 NISTNCSTAR 1-1B, WTC Investigation
Definitions

Table 7-1. Definitions (continued).

NYC Building Code (1968) NYC Building Code (2001)

NY State Building Construction

Code (1964)

Generally accepted standard

Grade Grade Grade, finished

Grade beam Grade beam

Grandstand Grandstand

Habitable room Habitable room Habitable space Hallway

Hanger

Height (buildings) Height (buildings) Height, building

High rise

Hoistvvay Hoistway Hoistway

Horizontal exit Horizontal exit Horizontal exit

Impact load Impact load

Inner court Inner court

Interior finish

Interior stair Interior stair

Interior trim

Kitchen

Kitchenette Lagging Lagging

Lamella Lamella

Legal open space

Live load Live load Load, live

Load, design

Load, imposed

Load, racking

Load bearing Load bearing

Loading ramp Loading ramp Lobby

Lot line Lot line Lot line Low rise Luminous ceiling

Mall Masonry

Mezzanine Mezzanine Mezzanine

Minor alterations Minor alterations

NISTNCSTAR 1-1 B, WTC Investigation 55
Table 7-1

Table 7-1. Definitions (continued).

Municipal Code of Chicago (1967)

BOCA Building Code - Basic Code

(1965) Comments

Garage Garage

Grade

Grade hallway

Habbitable room

Hallway, grade; hallway, public

Airplane hanger

Height Height, building

Hoistway enclosure

Light gauge steel construction

Limit control Load

Lobby

Lot line

Masonry

Mezzanine Mezzanine

56 NISTNCSTAR 1-1B, WTC Investigation
Definitions

Table 7-1. Definitions (continued).

NYC Building Code (1968) NYC Building Code (2001)

NY State Building Construction

Code (1964)

Mixed occupancy

Municipality

Multiple dw elling Multiple dwelling

Nonbeanng Nonbearing

Nonconcurrent loads Nonconcurrent loads Nonloadbearing Nonloadbearing

Nonhabitable space Nursing home

Occupancy Occupancy Occupancy

Occupancy group Occupancy group Occupancy classification

Occupant load Occupant load

Occupiable room Occupiable room

Occupied

Occupied space

Old-age home

Open parking lot Open parkmg lot Open parking structure Open parking structure Open parking structure Open shaft Open shaft

Ordinary repairs Ordinary repairs

Outer court Outer court Court, outer

Court, outer, width Owner

Parapet Parapet Wall, parapet

Parking lift, automobile

Parking tier Parking tier

Partition Partition

Passage way

Penthouse Penthouse

Pile Pile

Pile car Pile car

Place of assembly Place of assembly

Platform frame Platform frame

NISTNCSTAR 1-1B, WTC Investigation 57
Table 7-1

Table 7-1. Definitions (continued).

Municipal Code of Chicago (1967)

BOCA Building Code - Basic Code

(1965) Comments

Minimum habitable room height

Minimum habitable room size

Mortar

Municipality

Occupancy

Occupancy load

Occupiable room

Occupied

Ordinary construction Ordinary materials

Oriel window

Court, outer

Owner

Panel

Panel wall

Partition

Partition, bearing

Passageway

Penthouse Penthouse

Place of assembly

58 NISTNCSTAR 1-1 B, WTC Investigation
Definitions

Table 7-1. Definitions (continued).

NYC Building Code (1968) NYC Building Code (2001)

NY State Building Construction

Code (1964)

Pole footing Pole footing

Ponding Ponding

Premises

Private garage Pri\ ate garage

Projection, street

Property line

Public garage Public garage

Public space Public space Public space Rebound Rebound

Repair

Required Required Required

Residual deflection

Retaining wall Retaining wall Roof Roof

Roof covenng Roof covering Roof covering

Roof structure Roof structure

Safe area Safe area

School School

Self-relie\ ing construction Self-relie\ ing construction

Service equipment Service equipment

Shaft Shaft Shaft

Shall Shall Shall

Shell Shell

Spandrel wall Spandrel wall Wall, spandrel

Spray booth Spray booth

Stack Stack

Stage

Stairway

Store

NISTNCSTAR 1-1 B, WTC Investigation 59
Table 7-1

Table 7-1. Definitions (continued).

Municipal Code of Chicago (1967)

BOCA Building Code - Basic Code

(1965) Comments

Prefabricated

Prefabricated building

Prefabricated sub-assembly

Prefabricated unit

Preservative treated wood

Primary member

Professional engineer or architect

Public space

Reinforced concrete

Repair

Required

Roof

Roof covering

Roof structure Rubble masonry

Secondary member

Shaft

Shall

Solid masonry

Stage

Stairu'ay

60 NISTNCSTAR 1-1 B, WTC Investigation
Definitions

Table 7-1. Definitions (continued).

NYC Building Code (1968) NYC Building Code (2001)

NY State Building Construction

Code (1964)

Ston^

Street floor

Structural failure

Structure Structure

Sump pit Sump pit

Transfer column Transfer column

Uniformly distributed load Uniformly distributed load Use (used) Use (used)

Wall, curtain

Wall, panel

Wall, party

Watchman's system Yard Yard Yard

Yield strength Zone Zone

Zoning resolution Zoning resolution

NISTNCSTAR 1-1 B. WTC Investigation 61
Table 7-1

Table 7-1. Definitions (continued).

Municipal Code of Chicago (1967)

BOCA Building Code - Basic Code

(1965) Comments

Story

Street

Street lot line

Structure

Structural clay tile

Tile

Use group Apron wall

Wall, bearing Bearing wall

Curtain wall

Panel wall

Party wall

Division wall

Wall, non-bearing Non-bearing wall

Wall, parapet Parapet wall

Wall, retaining Retaining wall

Skeleton or panel wall

Spandrel wall

Yard

Zoning

62 NISTNCSTAR 1-1 B, WTC Investigation
Loads

Table 7-2. Loads

NYC Building Code (1968) NYC Building Code (2001)

NY State Building

Construction Code (1964)

Article 9 Loads Subchapter 9 Loads C304 Design Loads

Sub-Article 900.0 General Article 1 General C304-1 General Requirements

900.1 Scope Buildings and parts thereof, shall be capable of resisting all loads

actually imposed thereon without exceeding the allowable stresses prescribed in Articles 10

(Structural Work) and 1

(Foundation). In no case shall the assumed loads be less than the minimum values established

herein.

27-550 Same; In addition, within

special flood hazard areas, and below the flood datum, as described in Article 1 0 of

Subchapter 4 of this chapter, applicable load requirements of Reference Standard RS 4-5 [Annex A2]'' shall be applied.

C301-a

C304-1

C301 a- Buildings and parts thereof shall be capable of

sustaining safely their own

weight and the loads to which

they may be subject. C304-1 A building and all parts thereof shall be of

sufficient strength to support

the design loads and to resist the deformations caused by

such loads to which they may

by subjected, without exceeding the allowable

stresses as described in C305-

1. Such loads shall include the dead load and the following imposed loads where

applicable; live, snow, wind, and soil pressure including

surcharge, hydrostatic head, and impact loads.

900.2 Reference

Standards

TTie provisions of Reference

Standard RS-9 [Annex Al] shall be a part of this article.

27-551 Same

900.3 Definitions For definitions used in the

interpretation of this article, see

Article 2- Definitions.

27-552 Same CI08-3 Definitions

a. These are references lo Annexes lo this report that contain the items referenced in the codes.

NISTNCSTAR 1-1 B. WTC Investigation
Table 7-2

Table 7-2. Loads (continued).

Municipal Code of Chicago (1967) BOCA Building Code - Basic Code (1965) Comments

Chapter 68 Minimum Design Loads Article 7 Structural and Foundation Loads and Stress

68-1 General 700.0 Scope

Buildings or other structures hereafter erected shall be designed and constructed to support safely the minimum design loads, including dead loads as required in

this section, without exceeding the allowable stresses required in this code for the materials of

construction in the structural members.

The provisions of this article shall control the structural design of all buildings and stiuctures and their foundations hereafter erected to insure adequate strength of all parts thereof for the safe support of all superimposed live and special loads

to which they may by subjected in addition to their own dead load, without exceeding the allowable

stresses prescribed in the Basic Code or in accepted engineering

practice.

See Chapter 48 (Definitions). See Article 2. Definitions for the following tenns are also given in Section 70T0; Controlled

construction; Controlled materials; Foundation wall; Light gage steel construction; Load: (dead load; earthquake load; impact load; lateral

soil load; live load; wind load); Ordinary materials; Primary member; Secondary member; Steel

joist; Structural steel member.

Besides the definitions in Article 2, BOCA

includes some

additional

definitions for terminologies used

in Article 7.

702.0 Design Safe Load

702.1 Structural analysis. The safe load shall be determined by

accepted analysis or tests if not capable of analysis. 702.2 Check tests. When there is reasonable doubt as to the design

capacity.

703.0 Test Safe Load703.1 When required. When not capable of design by accepted

engineering analysis, any system

shall be subjected to tests prescribed

in Article 8 or test standards in Appendixes D, E [Annex A5], or

other tests accepted by building

officials. 703.2 Test load. When approved by

test, every structural assembly shall sustain without failure minimum

superimposed loads equal to 2.5 times the required live load; and

under the approved working load, the deflection shall not exceed the

limits prescribed in Section 804.

64 NISTNCSTAR 1-1B, WTC Investigation
Loads

Table 7-2. Loads (continued).

NYC Building Code (1968) NYC Building Code (2001)

NY State Building

Construction Code (1964)

Sub-Article 90]. 0 Dead Loads Article 2 Dead Loads

901.1 Construction

Materials and Assembled

Elements of

Construction

Except as provided in Section 901 .3. the dead load shall be the

actual weight of the building

materials or construction assemblies to be supported, computed from the unit weights

given in Reference Standard RS 9-1 [Annex Al]. Where unit weights are not established in RS 9-1. the actual weights may

be determined by analysis or from data in manufacturer's drawings or catalogs. Unit weights less than those given in RS 9-1 may be used only with

approval of the commissioner.

27-553 Same

901.2 Service Equipment

Provision shall be made for the weights of all building service equipment. The weights of such equipment (or the allowances

therefore) shall be included in the dead load. The weight of equipment that is part of the occupancy of a given area shall be considered as live load. See

also Sections C26-902.2 (b) (2) and C26-902.2 (d).

27-554 Same

901.3 Partition Loads

Weights of all partitions shall be

considered, using either actual weights or the equivalent uniform load given in (b) below.

(a) Actual loads. - Where actual

partition weights are used, the uniform design live load may be

omitted from the stnp of floor area under each partition. (b) Equivalent uniform load. - The equivalent uniform partition loads in Reference Standard RS 9-1 [Annex Al] may be used

in lieu of actual partition weights

except for bearing partitions or

partitions in toilet room areas

(other than in one- and rwofamily dwellings), at stairs and

elevators, and similar areas where partitions are concentrated. In such cases, actual partition weights shall be

used in design. Except as otherwise exempted, equivalent uniform loads shall be used in areas where partitions are not

definitely located on the plans, or

in areas where partitions are subject to rearrangement or

relocation.

27-555 Same

NISTNCSTAR 1-1B. WTC Investigation 65
Table 7-2

Table 7-2. Loads (continued).

Municipal Code of Chicago (1967) BOCA Building Code - Basic Code (1965) Comments

705. 0 Design Dead Load

705.1 Construction MatenalsIn estimating dead load for the purposes of structural design, the

actual weights of materials shall be

used, but in no case less than the

unit dead loads prescribed in Appendix J [Annex A5].

There are some

differences in the dead load values

prescribed in the NYC and BOCA

codes, e.g.: 12" hollow concrete

block: 85 psf (NYC) vs. 74 psf (BOCA); 6" hollow

concrete block: 42 psf (BOCA), vs. not found in NYC. No corresponding

provisions are given in NY State and Chicago codes.

705.2 Service Equipment The weight of all building service equipment shall be included in the dead load supported by the

structural frame.

NYC Building Code is more

specific than BOCA. The NY

State and Chicago

Building Codes do

not have comparable

provisions.

68-2.7 Partitions In office buildings or similar

structures in which subdividing

partitions may be erected, dead load

for such partition of not less than 20

psf shall be assumed

705.3 Partition LoadIn office or other buildings, provisions shall be made to support

the actual weight of the partitions where they occur or for an

equivalent uniform load, which

shall be not less than 20 psf of floor

area.

NYC 1968 and

2001: Equiv. unifonnly

distributed partition loads are given, which are less than

or equal to 20 psf

(See RS 9-1). NY State: No

relevant provisions

are given. Chicago & BOCA:

Not less than 20 psf

. ...

66 NISTNCSTAR 1-1B, WTC Investigation
Loads

Table 7-2. Loads (continued).

NYC Building Code (1968) NYC Building Code (2001)

NY State Building

Construction Code (1964)

Sub-Article 902.0 Live Loads Articles Live Loads C304-2 Live Loads

902.1 General In addition to the applicable dead. wind, and other loads, the building shall be

designed for uniform live loads, for concentrated live loads, or for concurrent combinations of uniform and

concentrated live loads, whichever

produce the greatest stress.

27-556 Same C304-

2.1

General

a- Loads set forth in Table C304-2.2 do not include unusual concentrations, such

as hea\'y machinery,

equipment, water tanks and

elevator machine loads. Where such loads occur,

suitable provisions shall be made for their support,

b- Where such unusual

concentrations do not occur,

structural members and floors

shall be designed to support

the uniformly distributed loads or the concentrated

loads in Table C304-2.2 [Annex B3], whichever

produce the greater stress.

902.2 Floor Live Loads(a) Uniformly distributed live loads.- The minimum design values established

in Reference Standard RS 9-2 [Annex A 1 ] for various occupancies or uses

shall be used subjected to the provisions of (d) below. Where the occupancy or use of a space does not conform to any

of those listed, the design load shall be

determined by the architect or engineer

subject to approval by the commissioner.

(b) Concentrated live loads.

( 1 ) The bldg shall be able to support concentrated li\ e load established in RS 9-2 [Annex Al]. placed so as to produce maximum stress. (2) Floors that support any items of machinery,

electrical or mechanical equipment, or

other concentrated live load in excess of 1000 lbs. (including the weights of pads

or bases) shall be designed to support such weight as a concentrated load or group of concentrated loads.

(c) Where RS 9-2 [Annex Al] indicates

that the concentrated live load is nonconcurrent with the uniform live load, it may be assumed that the total concentrated load is to be omitted when

the uniform load is present and that the

total uniform load is to be omitted when

the concentrated load is present.

(d) Conformance. - For purpose of determming that the magnitude of the

actual live load conforms to or is less than the mmimum design live load

established in this section, the actual uniform live load shall be approximated

by averaging the total load actually applied over a rectangular area of

1 50 sft having no side less than 8 ft.

27-557 Same C304-

2.2 Uniformly distributed andconcentrated live loads:

Shall be the greatest loads produced by the intended occupancy and use, but in no

case less than the minimum LL in confonnity with Table C304-2.2 [Annex B3]. Minimum loads for occupancies and uses not included in the table shall be

in conformity with generally accepted standards. Where a concentrated load is not

given, load shall be > 250 lbs on an area of lin. in diameter. Load values for some specific concentrated

load situations are given.

NISTNCSTAR 1-1B, WTC Investigation 67
Table 7-2

Table 7-2. Loads (continued).

Municipal Code of Chicago (1967) BOCA Building Code - Basic Code (1965) Comments

704.0 Design Live Load

704.1 Required live load: Shall be

the greatest load produced by the intended use and occupancy, but in no case less than required in section 707. 704.2 Load not specified.- Building

official shall determine the value

for the loads not listed in Table 13 [Annex 85].

As in the case of dead load, the live load provisions are categorized in a

similar, but not completely comparable way in the four codes (NYC 1968 and

2001 are the same). The values

specified are

similar.

68-2 Floor Loads68-2.1 Uniformly distributed floor

loads: The live loads assumed for purpose of design shall be the

greatest combination of loads that it

is estimated will be produced by the intended occupancies or uses; provided that the live loads to be

considered as unifomily distributed

shall be not less than the values

established in Table 68-2.1 [annex

B4], with reductions as permitted m

68-2.2.

68-2.3 Concentrate live load: Floors

shall be designed to carry the specified uniformly distributed live load or the following minimum

concentrated loads, whichever may

produce the greater stress. The

indicated concentrations shall be assumed to occupy an area of

2.5 sft and to be so placed as to produce maximum stresses in the affected members.

Office floors: 2000 lbs. Garages for passenger automobiles: 2000 lbs. Garages for buses and trucks: not less than actual rear wheel load when fully loaded.

707.0

708.0

Unit Live Loads

Concentrated Loads

707.1 Uniform live load.- The minimum uniformly distributed live load shall be as provided in Table 1 3 [Annex B5] and for all concentrated loads wherever they occur as provided in Section 708. 707.2 Heavy truck loads.- The floor loads for garages designed to house

trucks or buses exceeding 20,000 lbs shall be determined by

the actual load conditions; but in no

case shall the assumed load be less than 1 50 % of the max wheel load.

708.0 Concentrated loads.- Floors of buildings in the use groups

specified in Table 14 [Annex 85]

shall be designed to support the uniformly distributed live loads in Section 707 or the following

concentrated loads, whichever

produces the greater stresses. Unless otherwise specified, the indicated concentration shall be assumed to occupy an area of

2.5 sft and shall be positioned to produce maximum stress condition. Exceptions are given for steel joist constructions.

Code requirements

are similar.

68 NISTNCSTAR 1-1 B, WTC Investigation
Loads

Table 7-2. Loads (continued).

NYC Building Code (1968) NYC Building Code (2001)

NY State Building

Construction Code (1964)

902.3 Live Loads

for Sidewalks. Dnveways.

and

Railings

(a) Sidewalks and driveways. - All sidewalks and driveways or

portions thereof that are

structurally supported shall be

designed for a live load of 100 psf uniformly distributed and in accordance with the provisions of

Article 10. When subjected to intentionally or accidentally imposed wheel loads of vehicles, the sidewalks and driveways shall be designed for 600 psf uniformly

distributed load or maximum

vehicular wheel load that could be imposed thereon, whichever

develops greater stress. (b) Railings and parapets. - Other

than those for place of assembly,

railings and parapets shall be

designed to resist the simultaneous

application of a lateral force of 40

plf and a vertical force of 50 plf to the top of the railing. In places of

assembly, the lateral loads shall be

increased to 50 plf and the vertical load to 1 00 plf An exception is made for railings in one- and nvofamily dwellings, where a lateral force of 20 plf and a vertical force of 20 plf shall be considered. The

total lateral and the total venical

force shall be at least 200 lbs each. Intermediate and bottom rails: Shall be designed for simultaneous

application of 40 plf lateral and 50 plf vertical forces. For railings with solid panels: 20 psf. In parking area: 300 plf applied at least 21 in. above the roadway, but no less than 2500 lbs per vehicle.

27-558 (a) Same.

(b) Same

902.4 Columns in Parking

.Areas

Unless specially protected, columns in parking areas subject to impact of moving vehicles shall be designed to resist the lateral load due to impact and this load shall be

considered a load of infrequent occurrence. For passenger vehicles,

this lateral load shall be taken as a minimum of 2500 lbs. applied at least 21 in. above the roadway and

acting simultaneously with other design loads.

27-559 Same

902.5 Stage Areas using Scenery

or Scenic Elements

Shall be designed for 30 plf of

batten length. Locking rails shall be designed for a uniform uplift of 500 psf with a 1000 lbs concentration. Impact factor for batten shall be 75 % and for loft and head block beam shall be

25 %.

27-560 Same

NISTNCSTAR 1-1 B, WTC Investigation 69
Table 7-2

Table 7-2. Loads (continued).

Municipal Code of Chicago (1967) BOCA Building Code - Basic Code (1965) Comments

68-2.4

68-6

Special Loads

Other Loads

Driveways, sidewalks, spaces for storage of loaded or unloaded

trucks and buses, and tanks and

tracks shall be designed for the

actual weight.

Other loads: Railings- Shall be

designed to resist a horizontal thrust of 50 plf applied at the top of the

railing. Scuttles and SkylightsShall be designed to support a concentrated load of 200 lbs occupying an area of 2.5 sft and so placed as to produce maximum

stresses in the affected members.

702.3 Railings Railings around stairwells and other

floor openings shall be designed to

resist a lateral force applied

horizontally at the top of the

railings of 40 pif. and railings at front of balconies of theatres and

similar locations a lateral force of

50 plf In addition to the lateral load, railings and guards of outdoor

assemblies shall sustain a vertical load of 100 plf

The NYC Building Codes give the most

comprehensive

provisions. Chicago Code has

provisions similar

to those in the NYC

code. BOCA only

has provisions for

railings, not covering dnveways

and sidewalks. NY

State Code does not have provisions on

this topic.

70 NISTNCSTAR 1-1 B, WTC Investigation
Loads

Table 7-2. Loads (continued).

NYC BuUding Code (1968) NYC Building Code (2001)

NY State Building

Construction Code (1964)

902.6 Roof Loads Roofs and marquees shall be

designed for wind. live, and other loads as prescribed in (a) through

(d) below. It may be assumed that mauximum wind load occurs with

zero live load and that maximum

Ii\'e load occurs with zero wind

load. For dwellings an exception is made for awnings, canopies, and

patio covers, which may be

designed for a live load of 20 psf of

horizontal projection.

(a) Live load. - Minimum design

live loads; ( 1

) For roofs with slopes up to and including 20" from the

horizontal, the minimum design

live load shall be 30 psf of

horizontal projection. (2) For roofs with slope >20°. shall be 30 psf of

horizontal projection, reduced by

1 .0 psf for each degree in excess of

20". (3) For valleys, live load shall be increased to provide for accumulation of snow. (4) Other

shapes, established by architect or

engineer.

(b) Wind load. - The provisions of

Section C26-904.0 shall apply.

(c) Concentrated loads.- TTie provisions of Section C26-902.2(b)

shall apply.

(d) Special loads.- ( 1 ) For roofs used as promenades, assembly

areas, or roof gardens, design live load shall be as indicated in RS 9-2 [Annex Al] . (2) When roofs are intended for the ponding of water,

the roof shall be designed for maximum possible depth of water.

(3) Girders and roof trusses that are regularly utilized for repair of

vehicles shall resist, in addition to LL~W, a concentrated li\'e load of 2000 lbs applied on lower chord.

(4) When roofs are landscaped, the LL shall be 30 psf. the landscape

materials shall be considered

as DL computed based on saturated

earth, and the area adjacent to the landscape shall be considered as assembly areas unless otherwise

specified.

(5) When equipment is placed on

roof, the design shall provide

support.

27-561 Same C304 - 10(c) On roofs not used as promenades, the minimum

imposed load shall be 20 psf

perpendicular to the roof

surface, where snow plus wind loads total less than 20 psf

NISTNCSTAR 1-1 B. WTC Investigation 71
Table 7-2

Table 7-2. Loads (continued).

Municipal Code of Chicago (1967) BOCA Building Code - Basic Code (1965) Comments

68-3 Roof

Loads

68-3.1 Roofs having a pitch of less than 30" shall be designed for a live load normal to the roof surface (including snow load) of 25 psf of

roof area. Such live load may be

neglected in the design of roofs having a pitch of 30" or more, which shall be designed for wind

pressures as required in 68-4.3. 68-3.2 Roofs used for terraces, promenades or similar uses shall be

designed for a minimum live load of 60 psf.

711.0 Roof Loads The structural supports of roofs

shall be designed to resist wind and where applicable snow and EQ

loads in addition to the dead load and the live load. 711.1 Minimum roof load.- Flat and

pitched roof shall be designed for a

live load of not less than 20 psf of honzontal projection. In areas subject to snow loads, the roof shall be designed for 30 psf in the absence of specific information as described in 712.2. When used for incidental promenade purposes, roof shall be designed for a minimum of 60 psf; and 100 psf when designed for roof-garden or assembly use. 71 1 .2 Curved roofs.- Roofs with a radius not less than 1/2 span nor more than 3/4 span shall be

designed to resist 1 0 psf of

horizontally projected area on

buildings 40 ft or less in height; and

1 5 psf for buildings higher than 40 ft. 711.3 Overhanging eaves.

Minimum 60 psf.

NYC Code: 30 psf

(max), reduce 1 psf

/I" for pitch > 20". Chicago: 25 psf; 0

for pitch > or = 30". BOCA: > or =

20 psf of horizontal

projection. In areas subjected to snow

loads, 30 psf. NYC Building Codes gives the most

comprehensive

provisions for roofs subjected to special loads, while NY

State Code does not have such

provisions.

72 NISTNCSTAR 1-1 B, WTC Investigation
Loads

Table 7-2. Loads (continued).

NYC Building Code (1968) NYC Building Code (2001)

NY State Building

Construction Code (1964)

902." Moving

Loads

(a) General. - C26-902.2 (a) and

C26-902.2 (b). fb) Passenger vehicles.- RS 9-2 [Annex Al].

(c) Truck load.- Shall conform to RS 9-3 [Annex Al]. Impact shall be taken as 1 0 % of vertical load.

(d) Railroad equipment.- Shall conform to RS 9-4 [Annex Al].

(e) Crane runways and supports.

( 1

) Vertical loads: increase 25 % of

the lifted loads or 15 % of the wheel loads for impact whichever

is larger. (2) Horizontal load: alateral load; b- longitudinal load.

(f) Monorail beams and supports

(g) Loads on supports for elevators, dumbwaiters, and escalators.

(h) Loads on machinery supports

(i) Assembly structures

(j) Heliports and helistops

27-562 Same

902.8 Panial Loading

Conditions

(a) Uniformly distributed loads. -

In continuous framing and

cantilever construction, the design

shall consider live load on all spans and arrangements of partial live load that will produce maximum

stresses in the supporting members.

Tfie simplifications given in ( 1

)

through (3) below are permissible.

( 1 ) Floor and roof framing. -

a. For vertical live load applied to the level under consideration, the

far ends of the columns above and below that level may be assumed as

fixed.

b. Combinations of live load may

be limited to the following: 1 . Live

load placed on two adjacent spans.

2. Live load placed on alternate spans. The effects of live load on

spans more than two spans away

from the span under consideration may be neglected.

(2) Arches and gabled frames

(3) Columns

(b) Moving concentrated loads. - To be arranged to produce

maximum stress.

27-563 Same

902.9 Floor Load

to be Posted

(a) Posting required: Shall conform

to Section 27-225.

(b) Data required: Provisions are given for required data to be shown

for uniformly distributed and

concentrated loads.

27-564 Same

NISTNCSTAR 1-1 B. WTC Investigation 73
Table 7-2

Table 7-2. Loads (continued).

Municipal Code of Chicago (1967) BOCA Building Code - Basic Code (1965) Comments

Only the NYC

Building Codes

have provisions.

68-2.6 Partial Loads When the construction is such that the structural elements thereof act together as an elastic frame due to

their continuity and the rigidity of

the connections, the effect of such

partial loading as will produce

maximum stress in any member

shall be provided for in the design.

The NYC Building Codes give

simplified methods, and the most

detailed provisions; Chicago is the only

other code that gives provisions, which are general

in nature.

68-2.8 Posting of

Floor Loads

Provisions are given for buildings used for mercantile, industrial or storage purposes. Postings are not

required for buildings used for production and disti^ibution of

electricity, gas and steam.

Only NYC

Building Codes and Chicago Code have

provisions concerning posting of floor loads.

74 NISTNCSTAR 1-1B, WTC Investigation
Loads

Table 7-2. Loads (continued).

NYC Building Code (1968) NYC Building Code (2001)

NY State Building

Construction Code (1964)

Sub-Article 903.0 Live Load Reduction Article 4 Live Load Reduction

903.1 Roof Loads No reduction shall be permitted. 27-565 Same Roof load reduction allowed. See C304-2.1.

903.2 Floor Live Loads The unifonn live load to be used

for design shall be the basic values

in RS 9-2 [Annex Al] multiplied by the percentages given in (a) through (d) below.

(a) Except as provided in subdivisions (b),(c).and (d). the percentage in Table 9-1 [Annex

Bl] shall apply. Contributory areas

shall be computed in accordance

with C26-903.3.

(b) No live load reduction shall be

permitted for the following: members and connections (other than columns, piers, and walls) supporting floor areas used for storage (including warehouses,

librar\' stacks, and record storage): areas used for parking of vehicles: and areas used as place of

assembly, for manufacturing, and

for retail or wholesale sales. For

columns, piers, and walls supporting such floor areas, the maximum live load reduction shall be 20 %.

(c) No live load reduction shall be

permitted for calculating shear

stresses at the heads of column in

flat slab or flat plate construction.

(d) In lieu of the percentages gi\'en

in Table 9-1 [Annex Bl], the live load reductions for columns, piers and walls may be taken as 1 5 % of

the live load on the top floor, increased successively at the rate of

5 % on each successive lower

floor, with a maximum reduction of

50 %: and for girders supporting 200 sft or more of floor area, the

live load reduction may be taken as 15 %. The limitations of (b), (c), and (d) abo\ e shall apply.

27-566 Same C304-

2.1

c- Uniformly distributed live loads on beams and girders supporting other than storage

areas and motor vehicle parking areas, when such member supports 1 50 sft or more roof area or floor area per floor, may be reduced as follows: when the DL is not more than 25 psf, the reduction shall be not more

than 20 %. When the DL>25

psf and LL< or = 1 00 psf, the reduction shall not exceed the

least of the following 3

criteria: 60 %: 0.08 %/sft: or 100%*(DL-^LL)/4.33(LL)

(psf). d- For columns, girders supporting columns, bearing

walls, and foundation walls supporting 1 50 sft or more

roof area or floor area per

floor other than storage areas and parking area, the uniformly distributed LL

shall not be less than the following percentages of the

total LL on the following

levels: 80 % on the roof, the floor immediately below the

roof, the 2nd floor below the

roof; 75 % on the 3rd floor below the roof: 70 % on the 4th floor below; 65 % on the 5th floor below; 60 % on the 6th floor below; 55 % on the 7th floor below; 50 % on the 8th and subsequent floors below.

NISTNCSTAR 1-1 B. WTC Investigation 75
Table 7-2

Table 7-2. Loads (continued).

Municipal Code of Chicago (1967) BOCA Building Code - Basic Code (1965) Comments

68-2.2 Roof Load

Reduction Roof live load reduction is notpermitted.

721.0 Live Load

Reduction Roof live load reduction is not

pennitted. NY State Code is the only one that allows roof live load reduction.

68-2.2 Reduction of

Uniformly

Distributed Floor Loads

( 1 ) Columns, walls and piers.- Shall be designed to not carry less than

the specified percentage of live load of all floors above.

1 floor: 85 %; 2 floors; 80 %

3 floors: 75 %; 4 floors: 70 %

5 floors: 65 %; 6 floors: 60 %

7 floors: 55 %: 8 floors:50 %

(2) Foundations: same as (1 ). (3) Beams, girders and trusses.

Shall be designed to carry not less than the following percentage of

live loads based on the tributary area of the members: For tributary area of 1 00 sft or less: 1 00 %; more

than 100 sft and not more than 200 sft: 95 %; more than 200 and

not more than 300 sft: 90 %; more

than 300 sft: 85 %.

(4) When the dead load exceeds the

live load, the live load specified in 68-2.1 may be reduced by

multiplying with the ratio of the specified live load to the dead load, but in no case shall the reduced live load be less than 2/3 of the live load

specified in 68-2.1. These reduced

live loads are subject to all other provisions in Chap. 68. This

reduction in live load will not apply

to the ultimate strength method in concrete design. Exceptions: For storage rooms,

reduction shall not exceed 1/2 of

the percentage reductions provided

above.

721.0 Live Load

Reduction

721 .1 Live load not more than

1 00 psf: The design live load for any member supporting more than

1 50 sft may be reduced at the rate of 0.08 %/sq.ft. of area supported by the member, except for areas of

public assembly (no reduction). The

reduction shall exceed neither R as determined by the following

fomiula, nor 60 %:

R=100*(D+L)/(4.33L). D&L are design dead and live load per sft supported by the member.

721 .2 Live load more than 100 psf No reduction shall be made, except

that the design live load on columns may be reduced 20 %.

721 .3 Foundations and column

supports: The full dead load plus

the reduced live load shall be used

in the design of foundations and of

trusses or girders which support columns.

NYC Building Codes: Floor live load reduction is based on

contributary area and DL/LL ratio; alternative method

is based on number

of floors above. NY State: Live

load reduction for column is based on number of floors above; for beams

and girders, it is the same as in BOCA. Upper limit of 100 psf on

reducible LL exists. Chicago: Live load

reduction for columns is based

on number of floors above; for beams

and girders, it is based on tributary

area. Upper limit of

100 psf on

reducible LL exists. BOCA: 0.08 %/sft

for floors more

than 1 50 sft in area, but limited by R or 60 %.

76 NISTNCSTAR 1-1B, WTC Investigation
Loads

Table 7-2. Loads (continued).

NYC Building Code (1968) NYC Building Code (2001)

NY State Building

Construction Code (1964)

903.3 Contributor%- Floor .Areas(a) For the design of one-way and two-way slabs: the product of the

shorter span length and a width

equal to 12 the shorter span

length. Ribbed slabs shall be

considered as though the slabs were solid. fb) For the design of slabs in flat plate or flat slab construction: 1 2

the area of the panel.

(c) For the design of columns and

girders or trusses framing into columns: the loaded area directly supported bv the coluinn, girder, or

truss. For columns supporting more than one floor, the loaded

area shall be the cumulative total area of all of the floors that are supported.

(d) For the design ofjoists and

similar multiple members framing

into girders or trusses, or minor

filming around openings: nvice the loaded area directly supported but

not more than the area of the panel

in which the framing occurs.

27-567 Same

903.4 Foundations and Column

Supports

TTie live load to be supported by

the foundation or by trusses or

girders that suppon columns shall be the total column reaction reduced as provided in C26-903.2 and C26-903.3,

27-568 Same

C304-3 Snow

Loads

Minimum snow loads shall be m conformity with Tabic C304-3 [Annex B3] and the given snow map. and shall be

applied normal to the roof

surface. Minimum 30 psf for horizontal roof

NISTNCSTAR 1-1B. WTC Investigation 77
Table 7-2

Table 7-2. Loads (continued).

Municipal Code of Chicago (1967) BOCA Building Code - Basic Code (1965) Comments

Only the NYC

Building Codes

have provisions.

Only the NYC

Building Codes

have provisions.

68.3.1 Snow load is included as part of the roof load.

712.0 Snow Load 711.1 Minimum roof load.- 30 psf

in snow area. 712.1 Shape of roof - When the

effect of the shape of the roof as determined by actual test indicates

less or greater snow retention than

specified in the article, the roof load

shall be modified accordingly. 712.2 Special snow loads.- In sections subject to snow loads as indicated by the average snow

depth in the records of US Weather

Bureau, the design loads shall be

modified accordingly.

Similar in values; NYC Building Codes specify minimum roof load

as 30 psf, implying

the inclusion of snow load in roof

load specifications. Chicago code also includes the snow

load in roof load.

78 NISTNCSTAR 1-1 B, WTC Investigation
Loads

Table 7-2. Loads (continued).

NYC Building Code (1968) NYC Building Code (2001)

NY State Building

Construction Code (1964)

Siib-A riicle 904. 0 » ind Loads

Article 5 Wind Loads and

Earthquake Loads

The stnictural frame and exterior components of all buildings, signs, tanks, and other exposed constructions shall be designed to resist the pressures due to wind

as prescribed in RS 9-5 [Annex Al]. Wind

shall be assumed to act from any direction. For continuous framing, the effects of

partial loading conditions shall be

considered. RS 9-5:

1 . Design wind pressures on structural frames. Minimum design pressure due to wind acting on venical surfaces shall be in accordance with Table RS 9-5.1 [Annex

B!]. and minimum design pressure acting normal to horizontal or inclined surfaces

shall be in accordance with Table RS 9-5.2 [Annex Bl]. The occurrence of the pressure on vertical, horizontal, and inclined surfaces of the bldg shall be considered as simultaneous.

2. Wall element. For design of wall elements other than glass panels, the wind

pressure acting norma! to wall surfaces shall be 30 psf or a 20 psf suction, for all height zones up to 500 ft. These values shall be deemed to include allowance for gust factor. For height zones over 500 ft, the pressure

shall be specifically investigated, but not

less than the value in Table RS 9-5.1

.

3. Roof elements. Wind pressure acting on

roof elements supporting small contributory

area of wind presentment shall be 1.5 times

the value in Table RS 9-5.2.

4. Other bldg elements. Minimum wind

pressure to be used in the design of other bldg elements (signs, tanks, chimneys, etc)

shall be the values in Table RS 9-5.1 multiplied by the shape factors given in Table RS 9-5.3 [Annex Bl].

5. Eaves and cornices. Overhanging

elements of the bldg shall be designed for upward pressures of n^ ice the \ alues in Table RS 9-5.1.

6. Wind load by model test. In lieu of the design wind pressure established in sections

1 &2, design wind pressure may be

approximated from suitably conducted model tests. The tests shall be predicted on a basic wind speed of 80 mph at 30 ft level, and shall simulate and include all factors including pressure and suction effects, shape

factors, functional effects, gusts, and

internal pressures and suctions.

27-569 Article 5 Wind Loads and

Earthquake Loads

(a) Wind load; same

C3 04-4 Wind

Loads

Minimum wind loads shall be

in conformity with Tables C304-4a [Annex B3] and C304-4b [Annex B3], and

shall be applied normal to the surface. These loads are based on a design wind speed of 75 mph at a height of 30 ft above grade level. Minimum

wind load on signs shall be in conformity with generally accepted standards.

NISTNCSTAR 1-1 B, WTC Investigation 79
Table 7-2

Table 7-2. Loads (continued).

Municipal Code of Chicago (1967) BOCA Building Code - Basic Code (1965) Comments

68-4 Wind Load 68-4.1 Minimum design pressure. Buildings shall be designed and

constructed to withstand the horizontal pressures in Table 68-

4.1 [Annex B4], allowing for wind

from any direction. The height is to be measured above the average

level of the ground adjacent to the building. 68-4.2 Exterior wall. Shall be

designed and constructed to withstand the pressure required in 68-4. 1 , acting either inward or outward.

68-4.3 Roofs. Shall be designed

for outward pressure equal to 75 %

of those in Table 68-4.1 . Roofs

with slopes greater than 30" shall be designed for inward pressure

equal to those in Table 68-4.1

Overhanging eaves and cornices

shall be designed and constructed

for upward pressure equal to twice

those in Table 68-4.1. 68-4.4 Chimneys, tanks and

towers. Shall be designed and

consOTicted to withstand the pressures in Table 68-4.1 applied

to the projected vertical area

multiplied by the following

factors: square or rectangular

shape: 1 .0; hexagonal, octagonal, and round or elliptical shape: 0.8. 68-4.5 Provisions for signs are given. 68-4.6 Provisions for flagpoles are given. 68-4.7 For combined stresses due

to dead, live, and wind loads, the allowable stresses in materials may

be increased by 1/3, provided that the section thus determined is at least as strong as that required for dead and live load alone. Snow

load shall be considered a live load. 68-4.8 Provisions for overturning and sliding are given. 68-4.9 Adequate anchorage of the roof to walls and columns, and of

walls and columns to the foundations to resist overturning,

uplifting, and sliding shall be

provided. 68-4.10 Provisions shall be made

for wind stress during erection of a building or other structures.

713.0 Wind Load The structural frame of all buildings, signs, tanks and other exposed structures or parts thereof

shall be designed to resist the horizontal pressures due to wind in any direction, both inwardly and

outwardly, allowing for suction on

the leeward side, as provided in 714

to 718.

713.1 Torsional resistance- The

structural frame shall be designed to

resist the torsional moment due to eccentricity of the resultant load.

80 NISTNCSTAR 1-1 B, WTC Investigation
Loads

Table 7-2. Loads (continued).

NYC Building Code (1968) NYC Building Code (2001)

NY State Building

Construction Code (1964)

C304-5

Overturning

Force and Moment

Due to Wind

a- The overturning force

shall be the wind load. The

wind load shall be the load in Table C304-4a [Annex B3], and shall be applied only to the windward vertical surface above the horizontal plane under consideration, and to the rise of the roof The

resisting force shall be the dead load of the structure above the horizontal plane under consideration, plus the strength of material and

fastenings establishing continuity with the structure below.

b- The moments of stability and overturning shall be computed about the leeward edge of the horizontal plane under consideration,

c- The moment of stability of

the structure above the horizontal plane under

consideration shall be not

IpQ*: tVian 1 S timpQ tVip overturning moment due to wind.

C304-6

Sliding Force Due

to Wind

The sliding force due to wind

load, equal to the overturning

force, determined in conformity with C304-5,

shall be resisted by the dead

load of the structure above

the horizontal plane under

consideration, by anchors, and where applicable, by soil friction, providing a total resisting force equal to not

less than 1 .5 times the sliding

force. Anchors used to resist overturning may also provide

resistance to sliding.

NISTNCSTAR 1-1 B, WTC Investigation 81
Table 7-2

Table 7-2. Loads (continued).

Municipal Code of Chicago (1967) BOCA Building Code - Basic Code (1965) Comments

714.0 Wind on

Vertical Surfaces

714.1 Primary framing members.

Height not more than 50 ft; 1 5 psf. Height not more than 1 00 ft: 20 psf

for the surface above the 50 ft level. Height more than 100 ft: increase by 0.025 psf for each foot in excess of 100 ft above the 100 ft level. 714.2 Distribution of wind force: The wind pressure shall be

distributed between opposite walls,

2/3 as nomial pressure on the windward side and 1/3 as normal

outward suction on the leeward

side. 714.3 Secondary wall framing and

wall panels.- In buildings provided

with 1/3 or more wall openings,

internal wind forces of 10 psf shall be assumed to occur simultaneously

with the above external forces both

in pressure and suction. 714.3.1 External pressures.

External pressure to be considered

in the design of secondary wall framing and wall panels and

sheathing and their connections

shall be 1.5 times those determined

in accordance with 714.2. 714.3.2 Internal pressures.- If having 1/3 or more wall surface open, 1 0 psf internal pressure or 5 psf internal suction, whichever is critical, shall be considered in the design of secondary members. If having less than 1/3 wall surface open, half of the foregoing values

apply.

71 4.4 Design wind load for glass.

Appendix K-12 [Annex A5].

Minimum design wind loads required

in various codes on

a vertical surface up to a height of 1200 ft are

illustrated in Figure

2.NYC Building Code, Chicago

Code, and BOCA

also provide

provisions for secondary elements

such as wall

elements, roof

elements, and other building elements such as chimney,

etc. NY State Code, Chicago Code, and BOCA include provisions for overturning, sliding and uplifting forces caused by wind.

715.0 Wind Load

on Roofs Pnmary roof framing and truss: 715.1 and 715.2. Secondary roof framing etc.:

1 .5 times those determined in 715.1 and 71 5.2 for external pressure; provisions in 714.3 for internal pressure. 715.1 Pitched roofs. Provisions for the external wind force on primary

roof members are given in Exhibit B5-1 [Annex B5]. 715.2 Curved roofs. Provisions for curved roofs are given. 715.3 Test determination. The

effect of shape of irregular or unusual roofs may be determined by wind tunnel or equivalent tests. 715.4 Anchorage. Roof framing

shall be anchored to resist wind

uplift and sliding in excess of 75 %

of the dead load resistance.

82 NISTNCSTAR 1-1B, WTC Investigation
Loads

Table 7-2. Loads (continued).

NYC Building Code (1968) NYC Building Code (2001)

NY State Building

Construction Code (1964)

C304-7

Uplift Force

Uplift force due to wind or

hydrostatic head shall be

resisted by dead load, acting

directly or through anchors or

fastening, of not less than

1 .25 times the uplift force.

Article 5 Wind Loads and

Earthquake Loads

(b) Earthquake loads.- Every

building, structure and

portion thereof shall, at a minitnum, be designed and

constructed to resist the

effects of seismic ground

motions as prescribed in RS 9-6 [Annex A2]. which

adopted UBC Section 2312 from the 1988 UBC,

including the 1990 Accumulative Supplement.

NISTNCSTAR 1-1 B, WTC Investigation 83
Table 7-2

Table 7-2. Loads (continued).

Municipal Code of Chicago (1967) BOCA Building Code - Basic Code (1965) Comments

718.0 Overturning and Sliding718.0 The overturning moment due

to wind load shall not exceed 75 %

of the moment resulting from the dead load from the building, unless

the building is anchored to resist the excess overturning moment and the excess horizontal shear over sliding

friction.

716.0 Wind Loads

on Signs. Tanks and Radio Towers and Chimneys

716.1 Ground signs and towers.

1 5 psf for structures up to 50 ft in height, and 20 psf for structures over 50 ft in height. 716.2 Roof Structures.- Roof signs, tank towers, stacks, chimney, etc.: 30 psf

716.3 Shieldmg effect.- No

shielding effect of one element by

another shall be considered when

the distance between them exceeds 4 times of the projected smallest dimension of the windward

element. 716.4 Effect of shape: Wind

pressure on circular structures: 2/3 of the projected area. For hexagonal or octagonal structures: 7/8 of the projected area. 716.5 Radio towers: Shall conform

to the provisions in Section 427 and 428 unless smaller or greater loads

are approN'ed by test.

717.0 Unusual Wind

Exposures

717.0 The design load for buildings

subject to higher wind loads than

herein specified shall be determined by the prevailing conditions.

719.0 Earthquake Load

In regions where loss of life or damage of buildings resulting from EQs occur, buildings and structures

shall be designed to withstand

lateral forces as in Appendix K-1

[Annex A5], except as exempted in section 719.1. 719.1 Exemptions.- In zone "0", and where no loss of life or damage

to property were recorded,

regardless of zone, or when the building complies with any one or more of the following conditions, no EQ loading shall be required:

(a) is a 1- or 2- family dwellings

(b) is a minor accessory building;

(c) is not >3 stories or 35 ft in height; (d) is of skeleton frame

construction with wind and sway

bracing as required by approved

engineering practice for the type of frame used, and the least dimension

of the building is not less than 35 %

of the height.

NYC 2001 code added EQ

provisions; BOCA

includes EQ

provisions.

84 NISTNCSTAR 1-1B, WTC Investigation
Loads

Table 7-2. Loads (continued).

NYC Building Code (1968) NYC Building Code (2001)

NY State Building

Construction Code (1964)

Sub-Article 905.0 Other Loads Article 6 Other Loads

905.1 Eanh

Pressure and

Foundati on Loads

The provisions of Sub-article 1 1 02.0

shall apply.

1 102.3- Foundation wall and retaining wall shall be designed to resist in addition to the vertical loads acting

thereon, the incident lateral earth pressures and surcharges, plus

hydrostatic pressures corresponding

to the max probable ground water

27-570 Same C304-8 Soil pressure and hydrostatic head loads

1 . General. Retaining walls and

parts of the building below

ground shall be designed to withstand the following load, if applicable, in addition to other

loads: lateral loads due to adjacent soil: from hydrostatic head' from surcharge of fixed or moving loads: or uplift from

hydrostatic head.

2. Freestanding retaining walls. The moment of stability and

overturning shall be computed

about the bottom base edge on

the low earth side. The moment of stability shall not be less than 1 .5 times the overturning moment. The

resistance force due to soil friction shall not be less than

1.5 times the sliding force.

905.2 Bins and BunkersLoads on component parts of bins and

bunkers may be reduced for friction on sidewalls, provided that sidewalls and supports are proportioned for the increased vertical loads.

27-571 Same

905.3 Prestressing ForcesPrestressing forces shall be

considered in the design of

prestressed concrete structures, cable

structures, guyed structures, and

multiple intersecting truss webs

utilizing tension members.

27-572 Same

C304-9 Horizontal impact loads

a- Nonbearing partitions shall be designed to resist w/o

displacement at top or bottom a minimum linear load of 10 plf applied at mid height.

b- Parapet walls and railings

shall be designed to resist minimum 50 plf at top.

c- Provisions for parapet walls

or barriers at parking deck where vehicles are parked by a driver are given.

d- Provisions for barriers at parking deck, where vehicles

are parked mechanically, are given.

e- Provisions for grandstands

are given. f - Provisions for craneways

are given.

NISTNCSTAR 1-1 B, WTC Investigation 85
Table 7-2

Table 7-2. Loads (continued).

Municipal Code of Chicago (1967) BOCA Building Code - Basic Code (1965) Comments

68-5 Soil and

Hydrostatic

Pressure

Provisions for basement walls and basement floors are given.871.5 Lateral

Stability

Foundation walls which ser\'e as retaining walls shall be able to

resist lateral soil and hydrostatic pressure when subjected thereto.

The provisions in the various codes

are similar.

Only NYC

Building Codes

have provisions.

Only NYC

Building Codes

have provisions.

68-2.5 Impact Loads The live load assumed in this chapter may be assumed to include

a sufficient allowance to cover the

effects of ordinary impact. For

unusual impacts, suitable increase

shall be made in the assumed live load.

709.0 Impact Loads The unit live loads specified in Section 707 shall be assumed to include adequate allowance for ordinary impact conditions. Provisions shall be made for special uses and loads which involve

vibration and impact forces. Provisions for elevators, hea\'y machinery, craneways, and outdoor assembly structures are given.

NYC Building Codes do not have

provisions for impact loads. In Chicago and BOCA codes, ordinary impact

loads are assumed

covered in the prescribed live loads. NY State Code gives

piuviaiuiis lUl horizontal impact

loads.

86 NISTNCSTAR1-1B,WTC Investigation
Loads

Table 7-2. Loads (continued).

NYC Building Code (1968) NYC Building Code (2001)

NY State Building

Construction Code (1964)

905.4 Construction Loads

Provisions of Anicle 19- Safetv' of

Public and Property During

Construction Operations- shall apply.

27-573 Same C304-12 Loads imposed during

construction: All flooring, structural members, walls, bracing,

scaffolding, sidewalk sheds or

bridges, hoists and temporary

supports of any kind

incidental to the erection,

alteration or repair of any

bldg shall be of such strength

as to suffer no structural damage when subject to the temporary loads and wind

load imposed during

construction.

C304-1

Elevator machine loads: Shall conform to generally accepted standards.

905.5 Fluid Pressures The design of building components shall consider

pressures, both positive and

negative, of confined fluids and

gases.

27-574 Same

905.6 Ice The weight of 1 '2 in. radial thickness of ice on all surfaces

shall be considered as part of the

live load in the design of open

framed or guyed towers.

27-575 Same

905.7 Tliermal ForcesEnclosed buildings > 250 ft in plan shall be designed for 40 "F temperature change. Exterior exposed structures regardless of

plan dimensions shall be designed

for 40 ' F temperature change for concrete and masonry

construction and 60 "F for metal

construction. Provisions for piping

are also given.

27-576 Same

905.8 Shnnkage RC components shall be designed

for shrinkage of 0.0002 (standard weight concrete) or 0.0003 (light weight concrete) times the length betw een contraction joints.

27-577 Same

Sub-Article 906.0 Distribution of Loads Article 7 Distribution ofLoads

906.1 Distribution of Vertical LoadsDistribution of vertical loads to supporting members shall be determined on the basis of a recognized method of elastic analysis or system of coefficients of approximation. Elastic or

inelastic displacements of

supports shall be considered and,

for the distribution of dead loads, the modulus of elasticity of

concrete or composite sections

shall be reduced to consider

plastic flow. Secondary effects, due to warping of the floors shall be considered.

27-578 Same

NISTNCSTAR 1-1 B, WTC Investigation 87
Table 7-2

Table 7-2. Loads (continued).

Municipal Code of Chicago (1967) BOCA Building Code - Basic Code (1965) Comments

710.4 Construction Loads and

Erection

Stress

Provisions shall be made for temporary construction and wind

loads which may occur during the erection of the building, to prevent

overstressing.

\

Only NYC

Building Codes

have provisions.

Only NYC

Building Codes

have provisions.

Only NYC

Building Codes

have provisions.

Only NYC

Building Codes

have provisions.

Only NYCBuilding Codes

have provisions.

88 NISTNCSTAR 1-1 B, WTC Investigation
Loads

Table 7-2. Loads (continued).

NYC Building Code (1968) NYC Building Code (2001)

NY State Building

Construction Code (1964)

906.2 Distribution of Horizontal LoadsThe following provisions shall apply to superstructure framing only, and shall not apply to structures wherein horizontal loads are transmitted to the foundation by

stay-cables, arches, non-rectangular

frames, or by frames, trusses, or shear

walls not oriented in the vertical planes.

(a) Distribution of honzontal loads to venical frames, trusses and shear walls. Load should be assumed to be distributed by floor and roof systems acting as horizontal diaphragms. Proportion of total load to be resisted by any given vertical member shall be determined based on

relative rigidity, considering the

eccentricity of the applied load with

respect to the center of resistance. For

vertical trusses, web deformations shall be considered in evaluating the rigidity. (b) Distribution of horizontal loads within

rigid frames of tier buildings.- ( 1

Assumptions: Load distribution can be determined based on elastic analysis or. subject to limitations in (2) below, the following simplify ing assumptions:

Points of deflection in beams and columns are at their midspan and

midheight. respectively. The story shear is distributed to the columns in proportion to their stiffness. The change of length of columns due to axial effects of the horizontal loads may

be neglected. Vertical column loads due

to horizontal forces are taken by the

exterior columns only, or are resisted by

the columns in proportion to the column

distances from the neutral axis of the

bent.

( 2 ) Limitations: For buildings over 300 ft m height, change in length of the columns

due to the horizontal load shall be

evaluated. Simplifying assumptions shall be subject to the approval by the commissioner for the following

circumstances: For buildings over 300 ft or with a height-width ratio greater than

5; At rwo-story entrances or intermediate

floors; Where offsets in the building

occur: Where transfer columns occur; In any similar circumstances of irregularity or discontinuities in the framing.

(c) Distribution of load in self-relieving construction.- Assume connections are

fully rigid in resisting moments due to

lateral load, and that any larger moment

due to gravity or a combination of gravity and lateral load will be relieved by

deformation of the connection material.

(d) Structural walls and partitions.- If specifically designed to resist the applied

forces, they may be considered as contributing to the resistance or rigidity of the structure with regard to horizontal

load.

27-579 Same

NISTNCSTAR 1-1B, WTC Investigation 89
Table 7-2

Table 7-2. Loads (continued).

Municipal Code of Chicago (1967) BOCA Building Code - Basic Code (1965) Comments

Only NYC Building Codes have provisions.

90 NISTNCSTAR 1-1B, WTC Investigation
Structural Work

Table 7-3. Structural Work

NYC Building Code (1968) NYC Building Code (2001)

NY State Building

Construction Code (1964)

Article 10 Structural Work

Subchapter 10

Structural Work

Sub-Article 1000.0 Scope and General

Requirements

Article 1 Scope and General Requirements

1000.1 Scope The provisions of this article, supplemented by the additional requirements of Anicle 1 1 . shall establish minimum requirements

for materials, design, and

construction to be used for all structural elements in buildings.

27-580 Same; In addition, within

special flood hazard areas and below the regulatory flood datum, as described in Article 1 0 of Subchapter 4 of

this chapter, materials, designs and construction

required for structural elements by Reference

Standard RS 4-5 shall be

applicable.

C301 Genera! Requirements

c- Wherever structural material or assemblies are subjected to deterioration and

might become structurally unsound if unprotected,

protection in conformity with

generally accepted standards

for the material involved

shall be provided. Causes of

such deterioration include, among others, action of

freezing and thawing, dampness, corrosion, wetting and drying, and termites and

other destructive insects.

1000.2 Standards The provisions of Reference

Standard RS !0 [Annex A!]

shall be a part of this article.

27-581 Same. Reference standards have been updated.Foreword The State Building Code

Council publishes a list of

Generally Accepted

Standards. The list of

Generally Accepted

Standards for the 1 968 State Building Construction Code

(the oldest version the state has available) is listed in Annex A3.

NISTNCSTAR 1-1 B, WTC Investigation
Table 7-3

Table 7-3. Structural Work (continued).

Municipal Code of Chicago (1967) BOCA Building Code - Basic Code (1965) Comments

69-1 Scope The provisions of this section shall govern the quality and strength of

materials and methods of design and

construction hereafter used in the construction of buildings and structures. Materials and methods of design and

construction shall conform to the requirements of accepted engineering

practice and the recognized standards

consistent therewith.

800.0 Scope The provisions of this article shall govern the quality, workmanship

and requirements for all materials and methods and the minimum

specifications for enclosure walls and wall thickness hereafter used in the construction of buildings and

structures. All materials and methods of construction shall confonn to the approved rules and

standards for matenals and tests of

accredited authoritative agencies and the requirements of accepted

engineering practice as listed in Appendix A through 1 [Annex A5].

Provisions in all the codes are similar. The NY State Code

discusses

protection of

structural material

or assembles

against

deterioration.

41.1-6

69-4

Standards and Tests of Materials

Accepted

Engineering

Practice

All building materials shall be of a

quality to meet the intent of the building

provisions of this code, and shall confonn to requirements promulgated

as rules by the commissioner. Except as hereinafter specified for particular

materials, every material permitted to be used in the buildings or structures in the city shall meet the standards performance expectations for that material as prepared by the ASTM and

as adopted by that society in 1 958. Where such standards require acceptance tests for the determination of the performance and properties of

material, proper evidence of the making

of such acceptance tests shall be

submitted. Where in this code some

other standard of performance is set up

for any particular type of construction,

the same shall take precedence over ASTM, but any standard requirement in ASTM not in conflict with the same

shall remain in full force and effect.

The regulations, specifications, standards and tests of the technical organizations which are referred to in this code are hereby incorporated by

such reference with the same effect as though set forth. The standards [Annex A4] for (a) Foundations; (b) Masonry; (c) Wood;

(d) Reinforced concrete; (e) Reinforced Gypsum; (f) Steel and metals; (g) Plastering; (h) Single family dwellings; and (i) Abbreviations, shall be deemed

to represent accepted engineering

practice with respect to the materials, equipment, systems and methods of

construction respectively specified

therein.

All structural units and assemblies

shall be tested in accordance with

the standards listed in Appendixes

D, E and F [Annex A5]. In the absence of a testing procedure, the building official shall accept

authenticated reports which meet

the requirements of the Basic Code.

Material Standards, Structural Unit

Test Standards, Structural Assembly Test Standards,

Durabiliry Test Standards are listed in Appendixes C, D, E, and F [Annex A5], respectively.

The NYC Building Code uses the system of

Reference

Standards (RS). An

RS may be a referenced standard

(e.g. ACl 318-63),

a document that is not a standard

(e.g. an ACI

Committee Report),

a section of a code,

or may consist of a

set of requirements

that are spelt out. The NY State Code

is a performance

code. The Building Code Counsel of

the State publishes

a list of generally accepted standards. These standards

are deemed to comply with the performance of the code. The Chicago

Municipal Code

adopts reference standards listed in Section 69-4 of the code. The BOCABBC adopts

reference standards

listed in the appendixes to the code.

92 NISTNCSTAR 1-1B, WTC Investigation
structural Work

Table 7-3. Structural Work (continued).

NYC Building Code (1968) NYC Building Code (2001)

NY State Building

Construction Code (1964)

1000.3 Definitions See Article 2. 27-582 Same

1000.6 General RequirementsFor purposes of this code, the

strucrural elements of a building

shall normally include all floor, roof, and wall framing members

and slabs (but not including

slabs-on-grade); all piers, walls, footings, piles, and similar elements of the foundation; and

all other elements of both

foundation and superstructure which, m engineering practice, are proponioned on the basis of

calculated stress. Where doubt

exists as to the structural nature of an element, the provisions of

this article, and of Article 1 1. shall be deemed to apply only to an element in which the materials are stressed in excess of 33.3 % of the allowable stress values (without increase for infrequent stress conditions) for such material in its proposed

use, or to an element wherein

public safety would be involved

in the event of excessive

distortion under the applied

loads.

27-585 Same

103 Alteration of

Existing Buildings

103.1 Alterations exceeding 60 % of building value.- If the cost of making alterations in any

12-month period shall exceed 60 % of the value of the building, the entire building shall be made to comply with the requirement of this code.

1 03.2 Alterations berween 30 %

and 60 % of building value.

Only those portions of the building altered shall be made to comply with the requirements of

this code.

1 03.3 Alteration under 30 % of

building value - Those portions

altered may. at the option of the owner, be altered in accordance

with the requirement of this code, or altered in compliance

with their previously required condition and with the same or

equivalent materials and

equipment. pro\ided the general

safety and public welfare are not thereby endangered.

27-114 Alteration of existing buildings.- In addition to the same requirements as in the 1968 code, specifications are given for alterations that

shall conform with the requirements of this code

regardless of the magnitude

or cost.

The provisions in the rest of

this section are the same as the 1 968 code provisions.

C 105-2

Existing Building

2.1 General; Definition for the term "existing buildings"

is given.

2.2 Roof Covering; Whene\'er more than 25 % of

the roof covering of a building is replaced in any

1 2-month period, all roof

covering shall be made to comply with applicable

regulations of this code.

2.3 Addition or alteration; Any addition or alteration, regardless of cost, made to a building shall be made in conformity with applicable

regulations of this code.

2.4 Existing uses continued; Except as otherwise herein provided, nothing in this code shall require removal,

alteration, or abandonment

of. nor prevent continued occupancy or use of, an

existing building.

NISTNCSTAR 1-1 B, WTC hvestigation 93
Table 7-3

Table 7-3. Structural Work (continued).

Municipal Code of Chicago (1967) BOCA Building Code - Basic Code (1965) Comments

Only NYC

Building Codes try to clearly define the

applicability of the

structural provisions.

Chap.

78

Existing buildings

78-8 Alterations and repairs. 78-8.2 Change of occupancy, height or

area: (a) When the occupancy of an

existing building is changed from one

classification to another, the higher

provisions for the new occupancy shall be complied with, (b) When a building

is increased in height or area, the building shall comply with the applicable requirements of this code. 78-8.5 More than 50 %: Such buildings and structures shall be made to conform

to all requirements of this code

applicable to new buildings and

structures. 78-8.6 25 % to 50 %: All new

constructions shall conform to the requirements of this code for new

buildings or structures of like area, height and occupancy.

78-8.7 25 % or less: Certain exceptions can be made that allow the use of

materials that confonn to the strength and fire resistance for the materials with which the building is constructed. Otherwise, all new construction shall confonn to the requirements of this code for a new building. 78-8.8 Repairs to roof coverings: Not more than 25 % of the roof covering

shall be replaced in any 12-month

period unless the entire roof covering is made to confonn to requirements for new buildings.

706.0 Existing buildingIn the reconstruction, repair, extension or alteration of existing buildings, the allowable working

stresses used in design shall be as follows:

1 . Building extended: If altered by

an extension in height or area, all existing structural parts affected by

the addition shall be strengthened where necessary and all new

structural parts shall be designed to meet the requirements for buildings

hereafter erected.

2. Building repaired: When the uncovered structural parts are found

unsound, such parts shall be made

to confonn to the requirements for buildings hereafter erected.

3. Existing live load: When an

existing bldg heretofore approved is altered or repaired within the

limitation prescribed in Section 106.3 (alteration under 50 %) and

106.4 (alteration under 25 %), the structure may be designed for the loads and stresses applicable at the time of erection, provided that public safety is not endangered.

4. Posted live load: May be posted

for original approved live loads.

The provisions of

all codes other than

the NY State Building Code are broadly similar. The NY State Code

requires that any

addition or

alteration shall be made in conformity

with that code. It is silent as to the

structure being

altered.

94 NISTNCSTAR 1-1 B, WTC Investigation
Structural Work

Table 7-3. Structural Work (continued).

NYC Building Code (1968) NYC Building Code (2001)

NY State Building Construcrion

Code (1964)

1000.7 Matenals and Methods of

Construction

Materials and methods of

construction used in the manufacture and or placement

of structural elements in a building shall be subject to the requirements of

Sub-article 106.0 (Materials. Assemblies. Forms, and Methods of Construction), the inspection provisions established

in Tables 10-1 and 10-2 [Annex

Bl] and the detailed requirements of Sub-articles 1003.0 through 101 1.0 and Subarticle 1112.0.

27-586 Same C309

C303

Allowable

stresses of matenals

C309 Material requirements:

All structural units of natural or manufactured materials

shall comply with applicable

specifications of authoritative agencies, or shall be

subjected to test in conformity' with generally accepted standards in order

to determine their charactenstics.

C303 Allowable Stresses of

Materials C303-1 General

requirements: Safe workmg

stresses shall be assigned to materials in accordance with

their classification either as controlled materials or ordinary materials, and these

stresses shall not be exceeded

unless specifically permitted inC304-10. C303-2 Controlled materials; The safe working stresses of

materials which have been

identified and certified for qualify and strength shall conform to the specifications and stresses for such

materials. When a material is formed and cast in the field, tests prior to and during the construction shall be made,

and the composition and

strength of the material shall be certified. C303-3 Ordinary matenals:

Materials which do not conform to the requirements

for controlled materials shall be considered ordinary

materials, and their qualiry and safe working stresses

shall conform to the

specifications and stresses for ordinary materials in generally accepted standards. When quality and safe working stresses are not so

specified, they shall be determined by test in conformity with C305-1

.

When a matenal is formed

and cast in field, tests shall be made dunng the construction and its composition and strength

certified.

NISTNCSTAR 1-1 B. WTC Investigation 95
Table 7-3

Table 7-3. Structural Work (continued).

Municipal Code of Chicago (1967) BOCA Building Code - Basic Code (1965) Comments

69-3 Classification All materials and methods used in 701.0 Definitions 701.0 Definitions. The NYC has of the design and construction of Controlled Materials. Materials broad requirements. Construction buildings and structures shall be which are certified by an accredited The other codes

Materials classified as "controlled materials" and "ordinary materials" as defined

herein. 69-3.1 Controlled materials: Means

all materials shall be selected and

tested to meet the special strength, durability and fire resistance requirements. Design, shop and field details and inspection of construction

authoritative agency as meeting

accepted engineering standards for quality and as provided in Sections 722 and 800. Ordinary Materials. Materials which do not conform to the requirements of the Basic Code for controlled materials.

primarily address allowable stresses and make a distinction between

controlled and

ordinary materials.

shall be under supervision. 722.0 Allowable 722.1 Controlled materials.- The

69-3.2 Ordinary materials: Materials Working design and working stress of all meeting the requirements for Stress controlled materials shall conform minimum strength, durability and to the specifications and methods of

fire resistance for average materials design for accepted engineering without special selection, testing and practice or to the approved rules. supervision. 722.2 Ordinary materials.- Shall be

limited to the average unit working

stresses in Appendix K

[Annex A5].

722.3 New materials.- For materials which are not specifically provided

for in the Basic Code, the working

stresses shall be established by

tests.

800,1 General 800.1 The quality, use and

installation of all materials and methods of building construction

shall be controlled by the standards

for accepted engineering practice as

listed in Appendix B [Annex A5]

except where otherwise specifically provided in the Basic Code.

800.2 Material Standards

800.2 All building units used in wall, partition and floor construction and for fireproofing or

other insulation purposes shall comply with the applicable

standards listed in Appendix C

[Annex A5]. New

Materials

800.3 All new building materials. 800.3 equipment, appliances, systems or methods of construction not provided for in the Basic Code, and

any material of questioned

suitability proposed for use in the construction of a building or

structure, shall be subjected to the

tests prescribed in this article and in the approved rules to determine its character, quality and limitations of

800.5 Alternate Test Procedure

use. 800.5 In the absence of approved

rules or other accepted standards,

the building officials shall make or cause to be made the necessary

tests and investigations, or he shall accept duly authenticated reports from recognized testing authorities

in respect to the quality and manner

of use of new materials.

96 NISTNCSTAR 1-1 B, WTC Investigation
Structural Work

Table 7-3. Structural Work (continued).

NYC Building Code (1968) NYC Building Code (2001)

NY State Building

Construction Code (1964)

1000.9 Use of Used

and

Unidentified

Materials

The utilization of used

matenals and unidentified or ungraded materials shall be

limited to non-structural elements, except: (a) such

materials (or elements) may be

reused, or continued in use. at stress levels to which the materials or elements were

subjected in the previous

construction, or at load

capacity as demonstrated by

load test procedures as descnbed in 1002.4. (b) Unidentified materials may be graded by the recovery and test of representative samples, or by

other means satisfactory to the commissioner, (c) Used

materials shall be considered to be graded where the grade is clearly indicated on the approved plans for the existing construction and may be used

at the allowable stress levels for that grade of like materials

as established in the building code in force at the time the plans for the existing construction were approved.

27-588 Same

1000.10 Equivalent Systems of

Design

Nothing in this anicle shall be

construed to prohibit the use of any system of design, alternate

to those indicated, provided

that it can be demonstrated to the satisfaction of the commissioner that such system

of design will provide a factor of safety against structural

failure consistent with the requirements of Sub-article

1 uoJ . V inrougn i u i i .u. i ire safety in consonance with the requirements of Articles 3 through 8. and such other

characteristics pertinent to the safety of life, health, and

property as prescribed in this article or as may be required by

the commissioner.

Alternate or equivalent

materials or methods of

construction shall be subject to the provisions of C26-106.4.

27-589 Same C107

Acceptability

a- Compliance with

applicable provisions of

generally accepted standards, except as otherwise

prescribed in this code, shall constitute compliance with

this code.

b- Deviations from

applicable provisions of

generally accepted standards, when it shall have been

LUML 1 U j> 1 V C I y Uil-'VCU lllal dUCIl deviations meet the perfonnance requirements of

this code, shall constitute compliance with the code.

NISTNCSTAR 1-1B, WTC Investigation 97
Table 7-3

Table 7-3. Structural Work (continued).

Municipal Code of Chicago (1967) BOCA Building Code - Basic Code (1965) Comments

69-2 Used

Materials Used materials which meet the minimum requirements for new

materials and all other special requirements of the code shall be

permitted.

800.4 Used

Materials The use of all second-handmaterials which meet the minimum requirements of the Basic Code for new materials

shall be permitted.

The NYC Building Codes have more

specific requirements than

the Chicago and the BOCA Codes. The NY State Building Code has no

explicit requirement.

41.1 Building

Standards and Tests

41.1-1 For the purpose of insuring

public safety and for the purpose of

ascertaining the suitability of materials, methods, or systems of construction, or arrangements of materials, not

permitted by. or varying from, the performance requirements in this code,

but which are claimed to be equally as good as or superior to those permitted

hereunder, the mayor shall appoint a committee on standards and tests.

109.2 Accepted

Engineering

Practice

In the absence of approved rules, the regulations, specifications and

standards listed in Appendix A

[Annex A5] - Accredited

Authoritative Agencies, Appendix B [Annex A5]- Accepted

Engineering Practice, and Appendix C [Annex A5] - Accredited Material Standards,

shall be deemed to represent accepted engineering practice in respect to the matenal, equipment, system or method of construction

therein specified.

The various codes

investigated here

all pennit designs

that do not conform

to the codes, if the design can provide

equivalent or superior performance as required in the said code.

98 NISTNCSTAR 1-1 B, WTC Investigation
Structural Work

Table 7-3. Structural Work (continued).

NYC Building Code (1968) NYC Building Code (2001)

NY State Building

Construction Code (1964)

1000.11 Deferred

detailing Where strucrural elements are normally detailed on shop or working drawings, the application for the permit shall so state, and insurance of the permit shall be conditioned upon

future submission of such shop

or working drawings showing

the approval of an architect or

engineer. In cases where the

detailing is based on information

in manufacturer's catalogue, the application for appro\ al of the plans shall so state and issuance of such acceptance shall be

conditional upon submission of

statement by manufacturer,

attesting the accuracy of the data and that such data were deri\'ed

in conformance with this code. Where the detailing is based on

data published in technical documents of recognized

authority issued by, or accredited

by. the agency or association promulgating the applicable

reference standard cited in this code, such statements will not be

required.

27-590 Same

Sub-Article 1001.0 Structural Design - General

Requirements

Article 2 Structural Design - General Requirements

1001.1 Stabilirv- Except as provided in 1 1 1 1 .0 with regard to foundation

elements, a building, or any

element thereof shall be

proportioned to pro\ ide a minimum factor of safetv' of 1 .50 against failure by sliding or

overturning. The required

stability shall be provided solely by the dead load plus any

permanent anchorages which may be provided.

27-591 Same

1001.2 Bracing Unless otherwise specified in the reference standards, members

used to brace compression members shall be proportioned

to resist an axial load of at least 2 % of the total compressive

design stress in the member

braced, plus any transverse shear

therein.

27-592 Same

NISTNCSTAR 1-1B. WTC Investigation 99
Table 7-3

Table 7-3. Structural Work (continued).

Municipal Code of Chicago (1967) BOCA Building Code - Basic Code (1965) Comments

Only the NYC

Building Codes

have a specific provision concerning

issuance of permit

conditional upon

future submission of shop or working

drawings.

Only NYC

Building Codes

have an explicit statement concerning stability against sliding and

overturning.

Only the NYC

Building Codes

have this structurally important

requirement.

100 NISTNCSTAR 1-1 B, WTC Investigation
structural Work

Table 7-3. Structural Work (continued).

NYC Building Code (1968)

NYC Building Code

(2001)

NY State Building

Construction Code (1964)

1001.3 Secondan.'

Stresses

Secondar\' stresses in trusses shall be

considered and where of significant magnitude, their effects shall be pro^•ided

for in the design.

27-593 Same

1001.4 Combination of Loads

Dead loads, live loads (including impact) and reduced live loads, where applicable,

shall be considered as basic loads. Wind,

thermal forces, shrinkage, and unreduced

live loads (where live load reduction is permined by Article 9) shall be considered

as loads of infrequent occurrence. Members

shall have adequate capacity to resist all applicable combinations of the loads listed in Article 9, in accordance with the following:

(a) Where design is based on allowable working stresses, the loads as described in Article 9 shall be multiplied by the following factors and the design shall be based on the resulting load values: ( 1

) For

combinations of basic loads, only, the factor

shall be 1 .0. except that for the design of temporary structures (defined as a structure which will be in place 6 months or less) the factor shall be 0.75. (2) For any combination of one or more basic loads with any one load of infrequent occurrence, the factor shall be

0.75. except that for the design of temporary

structures the factor shall be 0.67. (3) For any combination of one or more basic loads with two or more loads of infrequent occurrence, the factor shall be 0.67. Exception-The provisions of RS 10-8 [Annex Al] and RS 10-9 [Annex AI]

relating to increases of allowable unit

stresses for short-time loading shall apply.

(b) Where design is based on ultimate

strength criteria (including plastic design of

steel structures and proportioning of suspended structures), the loads, as described in Anicle 9 shall be multiplied by

the factors indicated in C26-I0I0.5 (e) and

in the applicable reference standards. The

design shall be based on the resulting load

values. Exceptions- 1. Where combinations of loads

for which factors are given in the reference standard include the load of wind (or earthquake) the design additionally shall consider combinations of loads wherein

each other of the loads of infrequent occurrence as listed in this paragraph are substituted for the load of wind. -2. The

design also shall consider combinations of

loads wherein two most critical of the loads of infrequent occurrence are combined with

the basic loads. For such combinations, however, the factors indicated in the reference standards and in C26-1010.5 (e) for suspended structures, for the combination of basic loads plus one load of

infrequent occurrence may be reduced 1 5 %.

27-594 Second line: Wind,

earthquake,

thermal forces... Otherwise the same.

C304-I0 Combined

Loads

a- The stress due to wind may be ignored if it is less than 1/3 of the stress due

to DL plus imposed load excluding wind load, b- If the stress due to wind

exceeds 1/3 of the stress due to DL plus imposed

load excluding W, the allowable stress of the material may be increased by 1/3. c- On roofs not used as promenades, the min

imposed load shall be 20 psf perpendicular to the roof surface, where snow

plus wind loads total less than 20 psf

d- On roofs and eaves, snow or live load, and the wind load, shall be

considered as acting simultaneously in such combination as imposes

the greater stress.

NISTNCSTAR 1-1 B, WTC Investigation 101
Table 7-3

Table 7-3. Structural Work (continued).

Municipal Code of Chicago (1967)

BOCA Building Code - Basic Code

(1965) Comments

Only the NYC Building Codes have a requirement

concerning secondary

stresses in trusses.

68-4.7 For combined stresses due to dead, live, and wind load, the allowable stresses in materials may be increased 1/3, provided the section thus detennined is at least as strong as that required for dead and live load alone. Snow load

shall be considered a live load.

720.0 Combined

Loading The structural frame of all buildings shall be

investigated for the combined effect of lateral and vertical loading and

the individual members of

the frame shall be

proportioned as follows: 720.1 With EQ.- EQ+DL+LL+S; The

allowable working stress may be increased 33.33 %.

720.2 With wind.- W+DL+LL+S: The

allowable working stress may be increased 33.33 %,

720.3 Minimum section.

The section detennined from combined load shall be compared with that required for DL, LL and S

only. The section with the greatest strength shall be

used. 720.4 Wind neglected.

When the stress due to wind is less than 1/3 of the

stress due to dead load

plus live load, the wind

stress may be neglected.

The BOCA Code has simple and very explicit requirements. The NY

State and Chicago Code

requirements are similar. The NYC Building Codes

use reduced load factors where basic loads are considered together with

loads of infrequent occurrence, instead of

allowing increased allowable stresses. The

two schemes cannot be compared without a more

detailed study.

102 NISTNCSTAR 1-1B, WTC Investigation
Structural Work

Table 7-3. Structural Work (continued).

NYC Building Code (1968)

NYC Building Code

(2001)

NY State Building Construction

Code (1964)

1001.5 Deflection

Limitations The applicable provisions of the several reference standards cited in this article shall apply. In addition, the total of the dead plus live load vertical deflections (including effects of creep and shrinkage) of members supporting walls, veneered

walls, or partitions constructed of or containing panels of masonry, glass, or other frangible materials shall not exceed

1 '360 of the span.

27-595 Same C306-2 Performance criteria under test.- Under imposed load, the deflection shall not exceed

1/360 of the span when the mside is to be plastered, and

1/240 if it is not. When a roof is not to be used as a promenade, and the underside is not to be

plastered, the deflection shall not exceed 1/180 of the span.

Sub-Article 1002.0 Adequacy ofthe Structural Design

Article 3 Adequacy

ofthe Structural Design

C305 Analysis and test of

structural assemblies

1002.1 General The strucniral design of a member or assembly shall be deemed to be adequate if the design computations demonstrate conformance with the applicable standards noted m 1 003 .0 through 1 0 11 .0. Where,

because of practical difficulties, such computations cannot be executed, the

structural design may be deemed adequate

if the member or assembly is subjected to , and satisfactorily performs under, load

tests in accordance with the provisions of

1002.4 (a). Where there is a question as to the adequacy of a completed or partly completed construction, the provisions of

1002.2, 1002.3 and 1002.4(b) shall apply.

27-596 Same C305-1

General The capacity of an assembly to sustain dead and imposed loads w/o exceeding the allowable

stresses shall be determined by

any one of the procedures

described in this section, or by

an approved combination

thereof.

a- Design analysis. Stress shall not exceed safe working stress defined in generally accepted

standards or established by tests considering the reliability, durability, and uniformity of the material and its behavior under

stress. In no case shall the assigned safe working stress exceed 2/3 of the yield strength nor 1/2 of the ultimate strength of the material unless specified m C304-10.

b- Test.- Shall be made in conformity with generally accepted standards of

assemblies truly representative of the construction to be used,

in order to establish that such

assemblies conform to the performance criteria set forth in C306.

c- Comparison with an approved assembly of known

characteristics and behavior under load, which assembly is directly comparable in all essential characteristics to the assembly under consideration.

NISTNCSTAR 1-1B, WTC Investigation 103
Table 7-3

Table 7-3. Structural Work (continued).

Municipal Code of Chicago (1967) BOCA Building Code - Basic Code (1965) Comments

69-5.4 (a) Floor, wall and roof transverse

tests- (2) Deflection: Under design

live load, the deflection shall be not

greater than 1/360 of the span for plastered construction and 1/240 of

the span for unplastered construction.

804.2 Working

Load

Deflection

The deflection of floor and roof

assemblies shall not be greater than 1 /360 of the span for plastered construction; 1/240 of

the span for unplastered floor construction; and 1/180 of the span for unplastered roof

construction.

The provisions in various codes are

similar.

69-5.3 Test of

Structural Assemblies

When a structural assembly is not capable of design by accepted

engineering analysis, or when there is reasonable doubt as to its strength or

stability, the safe load-bearing

capacity of such structural assemblies

shall be determined by tests acceptable to the commissioner of

buildings. Such tests shall simulate the loads and conditions of application to which the complete structure will be

subjected in normal use.

803.0 Tests All structural units and

assemblies shall be tested in accordance with the standards

listed in appendixes D, E and F [Annex A5]. In the absence of a

testing procedure, the building

official shall accept authenticated

reports which meet the requirements of the Basic Code.

803.1 Strength tests.- Strength

tests prescribed in this code, or acceptable alternative tests, shall be made to determine the safe uniformly distributed working

load, when a structure is not capable of design by accepted

engineering analysis, or there is reasonable doubt as to the strength or stability of an

assembly. Structural load determinations shall include

transverse floor and roof, wall compression and racking, concentrated load, plaster bond,

puncture penetration and soil

tests. 803.1.1 Strength tests for Glass.

Shall comply with Appendix K12-B [Annex A5]. 803.2 Durability and endurance

tests.- Whenever required, the material or construction shall be

subjected to sustained and

repetitive loading to detemiine its resistance to fatigue, and to tests for durability and weather

resistance. 803.3 Maintenance test.- Tests of

all materials shall be made to assure the maintenance of the standards of approved matenals when reasonable doubt exists. 803.5 Tests of ser\'ice equipment

and devices.- Provisions are given

for ser\'ice equipment and

accessories that shall be included

in the tests. 803.8 Test specimens.- Test procedures shall confonr to those

listed in the appendixes.

104 NISTNCSTAR 1-1B, WTC Investigation
structural Work

Table 7-3. Structural Work (continued).

NYC Building Code (1968) NYC Building Code (2001)

NY State Building

Construction Code (1964)

1002.2 Questionable

Construction

If a construction shows open

cracks, spellings, other signs of

distress: or should inspection records show some significant deficiency of construction; or

tests of concrete or other

materials that have been

incorporated into the work

indicate deficiency of strength: or should there be a reasonable doubt as to the strength,

stability, or adequacy of the construction, such construction may be checked by

computation, or by core or load

tests. Should the adequacy not be verified within a reasonable

time, such construction shall be demolished or reinforced or

rebuilt to be made safe in conformance with the requirements of this code.

27-597 Same

1002,3 Core Tests of

Concrete

Construction

The adequacy of the concrete may be ascertained by the recovery and testing of cores. The compressive strength so determined shall meet the requirements for strength tests as described in RS 10-3 [Annex Al].

27-598 Same

NISTNCSTAR 1-1 B, WTC Investigation 105
Table 7-3

Table 7-3. Structural Work (continued).

Municipal Code of Chicago (1967) BOCA Building Code - Basic Code (1965) Comments

69-5.5 Workmanship Tests

(a) Whenever there is reasonable doubt

as to the stabihty or structural safety of

a completed building, the commissioner

of buildings may require a load test of

the building unit or portion of the

structure, (b) Unless otherwise provided

for in this code, the structure under

consideration shall be subjected to a supenmposed load equal to 2 times the design live load which shall be left in position for a period of 24 hrs. If during

the test or upon removal of the test load, the structure shows evidences of failure, he shall order reinforcement or modifications necessaiy to ensure adequacy of the structure for the rated capacity; or he may detennine the safe load capacity to which the structure

shall be limited, (c) The structure shall be considered to have successfully passed the test if the total deflection does not exceed the theoretical deflection computed by accepted

engineering fonnulae, or if the total deflection exceeds the theoretical value,

the structure shall be considered safe for

the design load if it recovers 75 % of

the maximum deflection within 24 hrs

after removal of the test load.

803.4 Workman

ship Test Whenever there is reasonable doubt as to the stability or safety of a completed building, the building official may require a load test of the building unit in question. Such existing structure

shall be subjected to rwo times the design live load for 24 hrs. If the

structure shows evidence of

failure, reinforcement or modifications shall be made, or a reduced working load limit shall be specified. The structure shall be considered to have met the requirements if the total deflection does not exceed the computed

theoretical deflection. When the

total deflection is greater than such theoretical value, the structure shall be considered safe

for the design load if it recovers 75 % of the maximum deflection within 24 hrs after removal of the

test load.

Only NYC

Building Codes

have provisions.

106 NISTNCSTAR 1-1 B, WTC Investigation
Structural Work

Table 7-3. Structural Work (continued).

NYC Building Code NY State Building Construction

NYC Building Code (1968) (2001) Code (1964)

1002.4 Load

Tests

(a) Prequalifying load tests: For structural members before they are incorporated into work.

( 1

) Test specimens: Shall be a true representation of the units to be used in work.

(2) Support conditions and interaction: Shall simulate the conditions of support in building, except partial fixit\' may be approximated by conditions of full or zero

restraint, whichever produces a more

severe stress condition.

(3) Strength requirements: The member or assembly shall be capable of supporting

a. Without visible damage (other than

hairline cracks) its own weight plus 150 %

of the design live load plus 1 50 % of any

dead load that will be added on the site. b. Without collapse, its own weight plus 50 % of its own weight plus 250 % of the design live load plus 250 % of the dead

load that will be added on the site. The

laner loading shall remain in place for a minimum period of one week. All loading

conditions described in Article 9 shall be

considered. The design live load shall be

the nominal value reduced for contributory

area as descnbed in Article 9. Except as permined under (5) below, units

to be tested shall be full size. Load bearing

wall and partition assemblies shall be

tested both with and without window and

door framing where such framing will be

included in the final assemblies. Test load may be reduced if the load tests are conducted and the results promulgated in a manner that will permit clear

differentiation between the dead and live load components added at the site. (4) Deflection requirement: The percentage of recovery of deflection caused by the superimposed load should be at least 75 %. The deflection under the design live load

shall not exceed that permitted in this

article. (5) Model tests. Tests on models less than

full size may be used to determine the

relative intensity, direction, and

distribution of stresses and applied loads, but shall not be considered as a proper method for evaluating stresses in, nor the

strength of. individual members unless approved by the commissioner for this

27-599 (a) Same C306 Performance Criteria under Test C306-1 General requirements: Buildings and their components

subjected to this code shall meet the performance criteria prescribed for each test. Failure to meet the criteria shall be evidence of noncompliance of

this code. C306-2 Under imposed load: When the assembly reacts by bending under the uniformly distributed imposed load, excluding impact, the deflection shall not exceed 1/360 of the span when the inside is to be plastered. When it's not

plastered. 1/240 of the span is the limit. When a roof is not to be used as a Promenade, and the underside is not to be plastered, 1/1 80 of the span is the deflection limit. C306-3 Under 1 .5 times imposed load:

a- Under its DL, and 1 .5 times the uniformly distributed imposed load, excluding impact, the assembly shall sustain the load w/o structural damage.

In testing floor assemblies and

assemblies in compression, the load

shall be applied twice, b- For floor assemblies, the residual deflection from the first load application shall not exceed 25 % of

the maximum deflection under the

load. After the 2nd application of the

load, the total residual deflection shall not exceed 1.1 times the residual deflection from the 1 st load. C306-4 Under 2 times imposed load: Under its DL and 2 times the uniformly

distributed imposed load, excluding

impact, the floor, roof, and wall assembly shall sustain load w/o

structural failure for a minimum of 24

hrs C306-5 Impact loads: Under an impact

load of 60 lbs falling 4 ft for floors,

1 .5 ft for walls, roofs and nonbearing

partitions, on an area 10 in. in diameter, applied perpendicular to the assembly

at its center, the assembly shall sustain no structural damage. C306-6 Racking loads: Where exterior walls and partitions react by racking, the racking deformation, while the assembly is sustaining the imposed

purpose. load, shall not exceed 1/400 of the height of the wall. Under 1 .5 times the load there shall be no structural damage, and under 2 times the load

there shall be no structural failure. C306-7 Transmitted loads: Fastening and connections shall be capable of

transmitting, w/o failure, twice the loads for which they are designed.

NISTNCSTAR 1-1B, WTC Investigation 107
Table 7-3

Table 7-3. Structural Work (continued).

Municipal Code of Chicago (1967) BOCA Building Code - Basic Code (1965) Comments

69-5 Tests 69-5.1 Test specimens: The selection and

construction of all test specimens and the details of test procedures herein shall confomi to the applicable standards of authoritative testing agencies and laboratories. 69-5.2 Test of matenals: (a) When the strength,

durability, weather-resistance and other qualities of a material necessary to the conditions of its use have not been established by accepted engineenng

practice, or are in reasonable doubt, tests shall be made as hereafter provided, (b) Tests of matenals

shall also be made where specifically required by

the provisions of this code, (c) Materials, when

required, shall be subjected to sustained and

repetitive loading to determine resistance to fatigue, and to tests for durability and weatherresistance when applicable to the use of the

material, (d) When not otherwise required in this code, the applicable standards and specifications of ASTM shall be deemed accepted practice in the conduct of tests of matenals, assemblies and

systems. 69-5.4 In evaluating the physical properties of

structural assemblies, the structural requirements

shall be based on the following conditions of

acceptance: (a) Floor, wall and roof transverse

tests: ( 1 ) Test load: Shall sustain superimposed

load equal to 2.5 times the design live load. (2) Deflection: Under design live load, the deflection

shall not be greater than 1/360 of the span for plastered construction, and 1/240 of the span for unplastered construction. (3) Residual deflection:

If the deflection is greater than the computed

theoretical deflection after 24 hrs under the total

static test load, upon removal of the load the construction shall recover not less than 3/4 of the

total test load deflection, (b) Wall and partition compression tests: (1 ) Test load: The assembly,

both with and without window framing, shall sustain without failure, superimposed loads equal

to 2.5 times the vertical design live load. (2) Recovery: After 24 hrs under the static test load, and after removal of the superimposed load, the specimen shall recover not less than 1/2 of all vertical and horizontal distortion and strain. (c) Wall racking tests:(l ) Test load: The assembly

shall sustain the design live load without excessive

distortion and not less than 2.5 times the design

live load without failure. (2) Recovery: After 24 hrs under the total static load, upon removal of

the load, the construction shall recover not less than 1/2 of the total deflection.

(3) Comparative tests: When not available from

existing authoritative test data, the building

official may require comparative tests of standard

traditional form of construction assemblies of

similar dimensions and sizes, to assist in determining the adequacy of the new construction.

(d) Concentrated load test: Where design for concentrated loads is required in Section 62-8.

floor constructions not capable of design shall be

subjected to a concentrated load test when such

loading exceeds in stress effect the prescribed uniformlv distributed load.

804.0

804.1

804.3

804.4

804.5

804.6

Conditions of Acceptance

Test Load

Factor

Working

Load

Deflection

Wall and

Partition Assemblies

Comparative

Tests

Concentrated Load Tests

Puncture

Penetration Tests

In evaluating the physical

properties of materials and methods of construction when

not subject to design by

accepted engineering analysis, the structural requirements shall be based on the criteria established by the following

provisions.

The test assembly shall sustain without failure, superimposed

loads equal to 2.5 times the design live load.

The deflection of floor and roof

assemblies shall not be greater than 1 /360 of the span for plastered construction; 1/240 of

the span for unplastered floor construction: and 1/180 of the span for unplastered roof

construction.

Bearing wall and partition assemblies shall sustain the load

test both with and without window framing.

May require comparative tests of assemblies of standard

traditional fonns of

construction to assist in determining the adequacy of the new construction.

All floor constructions specified

in Table 14 [Annex B5] shall be

subjected to the concentrated

loads therein prescribed when

such loading exceeds in stress effect the uniformly distributed load specified for such uses in Table 13 [Annex 35].

All finished floor constructions

in which light gage metal or

other thin matenals are used as

the structural floor shall withstand the application of a 200 lb concentrated load applied to the top surface on an

area of 1 in." at any point.

108 NISTNCSTAR 1-1B, WTC Investigation
Structural Work

Table 7-3. Structural Work (continued).

NYC Building Code NY State Building

NYC Building Code (1968) (2001) Construction Code (1964)

1002.4 Load

Tests

(b) Load tests of completed construction

( 1 ) Strength.- The construction shall be

loaded in rwo stages: (a) With all dead

load to which it will be subjected in serv ice plus a superimposed load equal to the design live load reduced as described

in Article 9: and (b) with a total load, including its own weight, equal to 1 50 %

of the total dead load to be supported in ser\'ice plus 1 80 % of the design live load, reduced for contributor^' area, which load

shall remain in place for a minimum of 24 hrs. (2) Deflection requirement.- Under the

first stage of loading, the deflection shall nor exceed that permitted in the applicable reference standard. The residual deflection

after removal of the second stage loading

shall not exceed 25 % of the calculated

elastic deflection under the superimposed

test load. The structure, after recovery of

the deflection, shall not show any

evidence of serious distress. (3) Interaction. -The loaded area shall be extended to include the loading of all framing and elements that contribute to the strength of the element by way of

interaction.

(4) Lateral loads.- The applied live load and lateral load components may be

adjusted as in 1001 .4. provided that the

stress condition under the load increments

described in (1 ) above is not more critical. (5) Reloading.- Not permitted.

(6) Limitation on use of load tests of

concrete structures.- Where the strength

tests of the concrete that initiated the requirement for load tests show strengths

less than 2/3 of the strength required by

the design of the specific element, the use of load tests to show the adequacy of the structure will not be permitted.

27-599 (b) Same, except for the following changes: The following paragraph

is added after the title "Load tests of completed

construction": "The

provisions of this subdivision shall apply to any f\'pe of construction where the appropriate

reference standard does

not provide for load test of completed

construction and the construction is questionable. When the appropriate reference standard provides for such load testing, the provisions of reference standard shall be used."

Sub-item (6) "Limitation on use of load tests of

concrete structures" is deleted.

C305-2 Load test on completed work

a- Safe pertbrmance under

load tests shall be evidence of

the acceptability of the construction.

b- The assembly shall be able

to sustain the dead load and two times the unifonnly

distributed imposed load, excluding impact, without

structural failure for a min

24 hrs.

C307 Exterior Protection C307-1 General requirement: Whenever structural material or assemblies are subject to deterioration and may become

structurally unsound under the proposed condition of use, adequate protection shall be

provided. C307-2 Exterior material: Exterior facing or covering

shall be resistant to causes of

deterioration as set forth in C301c w/o loss of strength or

loss of attachment which will render it unfit for use. The

material shall be treated if necessary. C307-3 Flashing C307-4 Waterproofing C307-5 Grade protection

NISTNCSTAR 1-1B. WTC Investigation 109
Table 7-3

Table 7-3. Structural Work (continued).

Municipal Code of Chicago (1967) BOCA Building Code - Basic Code (1965) Comments

Only NYC

Building Codes

have provisions.

110 NISTNCSTAR 1-1B, WTC Investigation
structural Work

Table 7-3. Structural Work (continued).

NYC BuUding Code (1968) NYC Building Code (2001)

NY State Building

Construction Code (1964)

Sub-A rtkle 1003.0 Masonry Article 4 Masonry

1003.1 General

Require- ments

(a) Lnreinforced masonr>'. -Shall meet the requirements ofRS 10-1 [Annex .W].

(b) Reinforced masonry. - Shall meet

the requirements of RS 10-2 [Annex Al].

27-6 Same C309

Material Require- ments

.All structural units of natural or manufactured materials

shall comply with applicable

specifications of authoritative agencies, or shall be subjected

to test in conformity with

generally accepted standards in order to determine their characteristics.

NISTNCSTAR 1-1B, WTC Investigation 111
Table 7-3

Table 7-3. Structural Work (continued).

Municipal Code of Chicago (1967) BOCA Building Code - Basic Code (1965) Comments

69-6 Prefabricated Construction

(a) Definition: A prefabricated assembly is a buildinti unit, the parts of which have been built up

or assembled prior to incorporation in the building.

(b) Performance standards: All requirements of this code and

accepted engineering practice.

(c) Tests: As in Section 69-5. Commissioner may require comparative tests.

803.7 Prefabncate

d

Construction

Tests

Shall meet all the requirements and

tests for at-site construction. The floor panels shall be assembled to form an

integrated specimen of not less than

3 units in width with 2 longitudinal

joints.

69-8 Welded

Constiuction

Shall be done under certified inspection. Only Chicago Code has explicit provisions.

Chapter 71 Masonry Construction Masonry Construction

71-1

71-2

71-3

General

Grouted

Brick Masonry

Reinforced

Brick Masonry

71-1 Design and construction

shall be in accordance with the provisions of the American

Standard Building Code

Requirements for Masonry

(1954).

71-2 Provisions for allowable compressive stresses are given.

71-3 Provisions are given for reinforcement and allowable

stresses.

835.0 Masonry

Wall

Construction

All masonry construction shall comply with the provisions of this

article governing quality of materials and manner of construction; and shall be of adequate strength and

proportions to support all superimposed loads within working

stresses prescribed in the Basic Code

and the standards of accepted engineenng practice. Provisions are also given concerning wetting of brick and precautions against freezing.

NYC Building Code and Chicago Code give general provisions for masonry

construction. NY

State code has

provisions only for general

construction, not

specifically for Masonry

construction. BOCA gives

specific provisions

for various masonry elements.

836.0 Bonding of Walls

Walls of solid, composite and hollow masonry and caviry and other hollow

walls shall be bonded in accordance

with accepted engineering practice. Specific provisions are given on

rubble stonewalls, buttresses and

piers, intersecting walls and

partitions, and erecting precautions.

837.0 Lateral Bracing of

Bearing Walls

All masonry bearing walls shall be

laterally supported by horizontal bracing of floor and roof framing or

vertical bracing of columns, buttresses or cross-walls at vertical or horizontal

intervals as specified in Appendix B

[Annex A5]; and provisions shall be made in the structure to transfer wind

pressures and other lateral forces to the foundations.

838.0 Chases and

Recesses m

Bearing Walls

Chases and recesses are prohibited in many situations. Provisions on maximum size of chases and recesses

are prescribed.

839.0 Corbelled &

Projected Masonry

Limitations on the use of corbels and

other projections are given.

840.0 Bearing on Hollowed

Unit Walls

Provisions on bearing area and

closure tile are given.

112 NISTNCSTAR 1-1 B, WTC Investigation
structural Work

Table 7-3. Structural Work (continued).

NYC BuUding Code (1968) NYC Building Code (2001)

NY State Building

Construction Code (1964)

1003.2 Identification (a) Masonrj- units. - Shall show the grade of the unit and

the compressive strength.

(b) Metal reinforcement. - Shall be able to identify the grade and size.

;"-60i Same

1003.3 Inspection Shall conform to Tables 10-1 and 10-2 [Annex Bl].

27-602 Same

Sub-Article 1004.0 Concrete Article 5 Concrete

1004.1 General RequirementsConcrete materials, design, and

construction shall meet the requirements of Reference

Standard RS 10-3 [Annex Al].

Precast concrete construction

utilizing a thin skin or slab

stiffened or supported by a system of ribs shall conform to the requirements of Reference

Standard RS 10-4 [Annex Al].

27-603 Concrete matenals.

design, construction,

quality-, inspection and

testing shall meet the requirements of

Reference Standard RS 10-3 [Annex A2]. The

rest is the same as in the 1968 Code.

All structural units of natural or manufactured matenals

shall comply with applicable

specifications of authoritative agencies, or shall be subjected

to test in conformity with

generally accepted standards in order to determine their characteristics.

1004.2 Identification of Metal- Reinforcement

Shall be able to identify' type, grade and size.

27-604 Same

NISTNCSTAR 1-1B. WTC Investigation 113
Table 7-3

Table 7-3. Structural Work (continued).

Municipal Code of Chicago (1967) BOCA Building Code - Basic Code (1965) nminAll

806.1 Identification All masonry units shall bear the

identification mark of the manufacturer consisting of a cast impression, embossing or painting.

NYC Buildmg Codes and BOCA

have similar provisions. NY

State and Chicago Codes do not have

provisions on

Identification.

Only NYC Building Codes have

provisions. Chap 73 Reinforced Concrete Construction

73-1 Portland Cement

Concrete

The design and construction of

reinforced concrete shall be in accordance with ACl 318-63.

73-1.1 Composite beams: Detailed

provisions for composite beams

are given.

830.0 Reinforcing

Steel

Shall comply with Appendix B

[Annex A5].

1. Identification. Shall be rolled with symbols or letter, or for wires, tagged, to identify the manufacturer and the grade of

steel.

2. High yield steel. If yield point is 50,000 psi or more, tension stress

in bending or compression stress in vertical column reinforcement shall not be more than 40 % of the yield

point: but shall not be more than 30,000 psi except in one-way slab or prestressed reinforcement.

817.0 Concrete Aggregates

Provisions are given for Aggregate

quality, Fire resistance. Grade 1 Concrete, Grade 2 Concrete, Size of Aggregates, and Special

aggregates.

114 NISTNCSTAR 1-1B, WTC Investigation
structural Work

Table 7-3. Structural Work (continued).

NYC Building Code (1968) NYC Building Code (2001)

NY State Building

Construction Code (1964)

1004.3 Mixes Concrete may be proportioned, batched, and mixed by any of the following methods:

(a) Method 1. Mixes with Minimum Cement

Factor.

( 1

) Minimum cement factor: The cement factor used in the work shall not be less than the factor given in Table 10-3 [.Annex Bl] for the corresponding strength of concrete.

(2) Water-cement ratio. - The concrete used in the work, whether proportioned on the basis of

preliminarv' tests or of prequalified mix designs,

shall be produced by using a water-cement ratio corresponding to a point on the strength vs. water-cement ratio curve representing (at a slump of 5 - '- 1 in. for concrete with gravel or stone aggregate and at a slump of 4 ^ - 1 in. for concrete with lighuveight aggregate) a strength of concrete at least 25 % higher than the specified strength called for on the plans. The

cement factor shall not be less than the factor shown in Table 10-3 [Annex Bl].

(3) Preliminary tests.- Except as provided in C26-1 004.3 (a)(4). preliminary tests of concrete

shall be made in advance of the beginning of any

concreting operation and

shall be subject to controlled inspection.

Preliminarv' tests shall consist of compressive

strength test of molded concrete cylinders made

in accordance with RS 10-17 [Annex Al] and RS 10-21 [Annex Al]. A curve representing the

relation between the average strength of the concrete at 28 days, or at earlier periods, and the water-cement ratio shall be established. The tests shall include at least 4 different water-cement

ratios and at least 4 cylinder specimens for each water-cement ratio. The cylinder strength tests shall be supplemented by tests to confirm that the cement and aggregates conform to the provisions of RS 10-3 [Annex Al].

(4) Prequalified mixes. - In lieu of the making of

preliminary tests for individual buildings or groups of buildings, a concrete producer may

pro\ ide concrete proportioned on the basis of

prequalified or previously accepted mix designs, which designs, including the applicable batching

weights, the results of applicable preliminary

tests and of tests to confirm that the cement and

aggregates conform to the provisions of RS 10-3 [Annex Al], shall be submitted not less often than once a year to the commissioner for review and prequalification. The preliminary tests shall be made under the supervision of an architect or engineer engaged by the producer. Concrete

proportioned according to prequalified mixes

shall be produced only from batch plants

satisfactory to the commissioner. Separate

prequalification shall be required for mixes

utilizing different combinations of aggregates and admixtures from all sources which are to be

utilized.

(5) Quality control and inspection of materials and of batching. - Shall meet the requirements in Table lO-I [Annex Bl],

27-605 Some terminologies are

different, e.g. the term "cement content" is used

in the 2001 code, rather than "cement factor" in the 1968 code. "Water-cement

ratio" is also referred to as "strength-cement ratio" in the 2001 code. The

wordings of some

provisions are also

different.

In the provisions for water-cement ratio, the 2001 code specifically gives provisions for lightweight and

hea\'yweight concrete.

1

NISTNCSTAR 1-1B, WTC Investigation 115
Table 7-3

Table 7-3. Structural Work (continued).

Municipal Code of Chicago (1967) BOCA Building Code - Basic Code (1965) Comments

818.0 Ready- Mix

Concrete

818.1 Control. Shall conform to Section 842 for reinforced concrete.

116 NISTNCSTAR 1-1 B, WTC Investigation
structural Work

Table 7-3. Structural Work (continued).

NYC Building Code (1968) NYC Building Code (2001)

NY State Building

Construction Code (1964)

1004.3 Mixes

(Cont'd)

(b) Method 11 - Performance concrete.

(1 ) Preliminar>' tests: Shall be in accordance with 1004.3 (a)(3). Mixes with performance data from previous projects, similarly proportioned, may be accepted, provided that acceptable performance data from such previous projects are provided and the conditions of paragraph (4) below

are met.

(2) Performance cement factor: Shall be

determined in (3) below.

(3) Strength, a. Concrete manufactured

with stone and gravel aggregate: the water-cement ratio shall correspond to a concrete strength, at design slump, at least 25 % higher than the specified strength

called for on the plan. The 25 % factor can be changed if satisfactory coefficient of

variation can be provided by the plant, but

in no case shall the water-cement ratio be

larger than that corresponding to a concrete strength 1 5 % higher than the specified strength, b. Concrete manufactured with lighrweight aggregate.

Tlie concrete shall be proportioned on a

strength vs. cement content basis in accordance with RS 10-65 [Annex Al] for

a strength at least 25 % higher than the specified strength. The provisions of a. above relating to reduction in the strength requirement for demonstrable quality control shall apply.

(4) Materials. Ingredients of the concrete

for the buildings shall be the same as those in the preliminary tests. (5) Batching. Provisions for batching plant

are given.

(6) Quality control and inspection of

materials and of batching. Provisions of

1004.3(a)(5) shall apply.

Method 11 is defined as "proportioning on the basis of field expenence". Similar

provisions are given as those

in the 1968 code.

Provisions are added for Method HI -"Average

Concrete. In lieu of making

preliminary tests, provisions

are given for the cement and

water content for average

concrete of 2000. 2500. or 3000 psi. Each load of

concrete shall be certified by

the producer.

NISTNCSTAR 1-1 B, WTC Investigation 117
Table 7-3

Table 7-3. Structural Work (continued).

Municipal Code of Chicago (1967) BOCA Building Code - Basic Code (1965) Comments

118 NISTNCSTAR 1-1B, WTC Investigation
structural Work

Table 7-3. Structural Work (continued).

NYC Building Code (1968) NYC Building Code (2001)

NY State Building

Construction Code (1964)

1004.4 DocumentationAll required anestations shall become

a part of the documentation to be filed with the commissioner, and shall be

subject to \'enfication by strength

tests, as hereinafter described, by

check sampling of ingredients, or by

such other inspections as the commissioner or the architect or engineer designated for controlled inspection may elect. Where

automated batching equipment is used, the tapes recording the batched

weights shall be available for inspection for a period of 2 years.

27-606 Similar

1004.5 On-Site

Inspections

Inspection of concrete and concrete

construction shall conform to Tables

10-1 and 10-2 [Annex Bl] and the provisions of this article, (a) Controlled inspection. (1) Strength

tests; Shall be performed on all structural concrete. The provisions of RS 10-3 [Annex Al] shall apply. Detailed provisions for concrete

cylinders are provided. (2) Additional

tests: Each sample recovered for strength test shall be additionally checked for slump, air content, unit weight, and temperature in accordance with RS 10-3 [Annex

Al]. (3) Forms, reinforcement and

placing: Provisions for the size and

dimension of the forms, sizes and

positions for reinforcement, and the placement of concrete are provided,

fb) Other required inspection. Quality

control and inspection shall be provided for operations that are not designated for controlled inspection.

27-607 Provisions in (a)- ( 1 ) and (2) are

similar, but more

comprehensive. The title for (a)- (3) is changed to "Controlled

Inspection Log Book", and

similar but more comprehensive

provisions are given. Provisions

in (b) are also similar, but more

detailed and comprehensive.

1004.6 Admixtures

Admixtures, other than air-entraining and water-reducing agents, may be used only when batch plant inspection by a representative or employee of

the architect or engineer designated

for controlled inspection is provided. Where admixtures are used, the provisions of RS 10-3 [Annex Al]

shall apply except that water-reducing

agents shall conform to RS 10-44 [Annex Al]. Type A or D. with the requirement for compressive strength increased to 1 1 0 % and for durability increased to 1 00 %. In addition, no

anti-freeze agents shall be used. Admixtures shall be added only through calibrated dispensing

devices. Tliese dispensers shall be

regularly inspected and certified as to accuracy by the manufacturer of the admixture.

27-608 Admixtures may be used in the concrete only where included in the preliminary test mixes

proportioned in accordance with

the provisions of Section 27-605

(a) (3) or mixes proportioned in accordance with the provisions of RS 10-3 [Annex A2]. In the case of mixes proportioned in accordance with section 27-605

(c). there shall be no reduction of

the cement content called for in Table 10-3 A [Annex 82]

because admixtures are used in the mix. Where admixtures are used, the provisions of RS 10-3 [Annex A2] and RS 10-44 [Annex A2] shall apply. In addition, no anti-freeze agents

shall be used. Admixtures shall be added in measured quantities

in conformance with the accepted mix design.

NISTNCSTAR 1-1B, WTC Investigation 119
Table 7-3

Table 7-3. Structural Work (continued).

Municipal Code of Chicago (1967) BOCA Building Code - Basic Code (1965) Comments

120 NISTNCSTAR 1-1 B, WTC Investigation
structural Work

Table 7-3. Structural Work (continued).

NYC BuUding Code (1968)

NYC BuUding Code

(2001)

NY State Building

Construction Code (1964)

1004.7 Licensed

concrete

testing laboratorie

s

All tests shall be performed by licensed testing laboratory.

27-609 Much more detailed provisions are given for the responsibilities of

licensed concrete testing laboratory.

1004.8 Short-span Concrete

Floor and Roof

Construction Supported on Steel Beams

The empirical equations in (c) and (d) below shall apply only where the steel beams are placed or encased in a manner that will prov'ide section for

the transfer of shear from slabs to beams larger or equal to the slab thickness required by the said equations.

(a) Concrete. -Concrete shall have a minimum

compressive strength at 28 days of 700 psi. (b) Reinforcement.- Reinforcement shall be or

function as continuous. The main reinforcement

shall be at least 0.15 % of the gross section where

continuous steel fabric is used and at least 0.25 %

when other forms of steel are used. All reinforcing

shall be draped, with 1 in. concrete cover at the center of the span and over the support (between

the center of the reinforcing steel and the bottom

or top of the slab).

(c) Minimum slab thickness - Shall be determined by the following Eq.. but not less than 4 in. : t=L/2-(w-75)'200:

t=total thickness, L=clear span between steel flanges (ft), \v=gross uniform load (dead +

reduced live)(psf). (d) Allowable load.- Shall be determined by

following Eq.: w=3CAs^'

As=area of main reinforcement, C=coefficient dependent on cone, and steel properties.

(e) Openings in floors and roofs.- Provisions of

the size of the openings that require to be framed

is given.

27-610 Same

1004.9 Pneumatically Placed Concrete

Shall conform to RS 10-15 [Annex A 1]. 27-611 Added: 27.611.1 Conveying concrete by

pumping methods.- All classes and strengths of

concrete may be conveyed by pumping

methods. All materials and methods used shall conform to the rules promulgated by the commissioner.

1004.10 Formwork Shall conform to Anicle 19, 27-612 Formwork, slip form

construction, lift method

construction, precast and

prestressed construction.

- Shall conform to SubChapter 19.

1004.11 Concrete

Utilizing Preplaced Aggregate

The use of concrete formed by the injection of

grout into a mass of preplaced coarse aggregate

will be permitted where it can be demonstrated by

successful prototype installation that the proposed

mix. materials, and methods of placement will produce a concrete of the specified strength and

free of areas or inclusions of uncemented

aggregate. Detailed provisions are given for prototypes, in-place concrete and inspection.

27-613 Same, except added:

27-613.1 Precast and

prestressed concrete.

27-613.2 Thin-section

precast concrete

construction.

NISTNCSTAR 1-1B. WTC Investigation 121
Table 7-3

Table 7-3. Structural Work (continued).

Municipal Code of Chicago (1967) BOCA Building Code - Basic Code (1965) Comments

. - - '

Only NYC Building Codes have

provisions.

848.0 Pneumatic

Concrete

Provisions on the placement and mix of pneumatic concrete are

given.

Only NYC Building Codes and BOCA

Code have

provisions.

Only NYC Building Codes have

provisions.

Only NYC Building Codes have

provisions.

122 NISTNCSTAR 1-1 B, WTC Investigation
structural Work

Table 7-3. Structural Work (continued).

NYC Building Code (1968) NYC Building Code (2001)

NY State Building

Construction Code (1964)

Sub-Article 1005.0 Steel Article 6 Steel

1005.1 General Requirements

Materials, design, and construction methods shall meet the requirements of the following

reference standards:

(a) Structural steel- RS 10-5 [Annex Al].

(b) Light gauge cold formed steel - RS 10-6 [Annex Al].

(c) Open web steel. - RS 10-7 [Annex Al].

27-614 Same All structural units of

natural or manufactured

materials shall comply

with applicable

specifications of

authoritative agencies, or

shall be subjected to test in conformity with

generally accepted

standards in order to determine their characteristics.

NISTNCSTAR 1-1B, WTC Investigation 123
Table 7-3

Table 7-3. Structural Work (continued).

Municipal Code of Chicago (1967) BOCA Building Code - Basic Code (1965) Comments

Chap. 74 Steel and Metal Construc tion Provisions for Steel Construction

74-1

74-2

74-3

74-4

74-5

74-6

Structural

Steel Design

Light Gauge

Steel Structural Members

Steel Joist Construction

Light Weight

Metal

Alloys

Cast Iroi

Special

Steels

Design, fabrication and

erection of stmctural steel shall be in accordance with

the following document:

Specifications for the Design,

Fabrication and Erection of

Stioictural Steel for Buildings, AISC 1963. Exceptions that do not follow this document

are given.

Conform to Light Gage Cold- Fonned Steel Design Manual,

AISI 1962. Exceptions are

also given.

Conform to Open Web Joists- Standard Specifications and Load Tables. SJl-1963.

Aluminum, magnesium and

other lightweight metals and

alloys shall be used only after approval by commissioner.

Conform to Standard

Specifications for Gray Iron Castings- ASTM A48-62.

Detailed provisions are given

for the niin thickness requirements for various

structural members. Cast iron columns shall not be used where subjected to eccentric load which produce a net tension in the material, nor to

resist wind load. Core of superimposed columns shall be of same dimensions above

and below a splice. Cast steel shall confonn to ASTM A27-

62 (for grade 65-30) and A 148-60 (grade 80-50).

Silicon, nickel and other alloy and high strength steels shall conform to the applicable standards of accepted

engineering practice and may

be used only under a controlled materials procedure. Detailed provisions are given for the

stress, identification, and

allowable unit stresses in columns.

827.0

828.0

829.0

831.0

832.0

833.0

834.0

723.0

Structural Steel Construction

Formed Steel Construction

Steel Joist Construction

Cast Steel Construction

Cast Iron Construction

Special Steels

Light Weight

Metal Alloys

Alloy and

Special Steel

Structural steel construction used in

all buildings and structures shall be

fabricated from materials of unifomi

quality, free from defects that would

vitiate the strength or stability of the

structure. Workmanship, design,

fabrication, transportation and

erection shall conform to accepted

engineering practice as defined by

the standards listed in Appendix B

[Annex A5]. Provisions are given

for Plans, Temporary and special

stresses. Shop drawings. Welding, and Painting.

Design; Shall be based on allowable

unit stresses and maximuin

deflections in accordance with Appendix B [Annex A5]. Provisions

are also given for: Minimum

thickness of metal: Secondary

structural systems; Roof decking;

Protection; and Tests.

Provisions are given for the design,

protection, height and area

limitations, and tests of steel joist constructions.

Provisions are given for materials, higher strength cast steel, and

welding cast steel. Provisions are given for materials,

limitation of use, multi-story columns, and thickness of metal.

Identification: Alloy and high

strength steel shall conform to the standards of accepted engineering

practice. Shall be clearly marked. 2. Design and workmanship; Shall confonn to the requireinents of

approved rules.

Shall be used in accordance with Appendix B [Annex A5].

The use of alloy, high carbon or other special high-strength steels

shall be penmtted in the design and

construction of buildings and

structures as controlled materials and as prescribed in Section 833 in accordance with accepted

engineering practice.

NYC Building Codes give general provisions for steel construction. Chicago and BOCA

Codes give more

specific provisions

for vanous steel structural systems. The NY State Code

has provisions only

for general

construction, it has

not specific provisions for steel.

124 NISTNCSTAR 1-1 B, WTC Investigation
structural Work

Table 7-3. Structural Work (continued).

NYC Building Code (1968) NYC Building Code (2001)

NY State Building

Construction Code (1964)

1005.2 Identification Shall be marked or handled so

that they can be positively

identified.

27-615 Same

1005.3 Qualit\' ControlProvisions of Tables 10-1 and 10- 2 [Annex Bl] shall apply. Detailed provisions for welding

and inspection are provided.

27-616 Same

Sub-Article 1006.0 Wood Article 7 Wood

1006.1 General RequirementsMaterials (other than non-stress grade lumber), design and

construction methods shall meet

the requirements of the following

reference standard:

(a) Lumber and timber - RS 10-8 [Annex Al].

(b) Plvwood - RS 1 0-9 [Annex

Al].

'

(c) Structural glued-laminated lumber - RS 1 0- 1 8 [Annex A 1 ]

27-617 Same All structural units of natural or manufactured materials

shall comply with applicable

specifications of authoritative agencies, or shall be subjected

to test in conformity with

generally accepted standards in order to determine their characteristics.

1006.2 Identification Provisions for identification requirements are given

27-618 Same

1006.3 Use of NonStress Grade Wood

Conditions to which the use of

non-stress grade wood should be

limited are given.

27-619 Same

1006.4 Quality Control

Inspection of the fabrication of

glued-laminated assemblies, as

stipulated in Table 10-2 [Annex

Bl], shall include a check of sizes of members of fit, and of gluing

operations.

27-620 Same

1006.5 General

Construction Requirements

Provisions for various types of wood members are provided.

27-621 Same

NISTNCSTAR 1-1 B, WTC Investigation 125
Table 7-3

Table 7-3. Structural Work (continued).

Municipal Code of Chicago (1967) BOCA Building Code - Basic Code (1965) Comments

Only NYC Building Codes have

provisions. Only NYC Building Codes have

provisions.

Chapter 72 Wood Construction

72-1

72-2

72-3

72-4

General

Maximum

Allowable

Unit

Stresses

Bolted

Joints

Ventilation

Abbreviations; NLMA: National Lumber

Manufacturers Association. NDS: National Design

Specifications for stress-grade lumber and its fastenings

Wood structural members shall be of sufficient size to carry the dead + live load without exceeding the allowable unit

stresses required in this chapter. Adequate bracing and bridging to

resist wind and other lateral forces

shall be provided. The applicable provisions of NDS shall govern.

Maximum allowable unit stresses are given in Table 72-2 (a) [Annex B4, for ordinary

materials].

Provisions for bolted joints are given.

Provisions for ventilation are given.

853,0

854.0

855.0

856.0

857.0

Lumber and Timber

Construction

Hea\'y Timber Type

Construction

Wood Frame

Construction

Stress Skin

Panels

Glued. Laminated

and Built-Up Lumber

Construction

Provisions are given for the Design, Minimum dimensions.

Fabrication, Trimmer and Header

beams. Bearing and anchorage on

girders, and Maintenance.

Provisions are given for Wood,

Other structural matenals. Columns. Floors, and Beams and

girders.

The exterior walls, interior partitions, floors and roofs of wood

frame construction shall be

designed and constructed to develop adequate strength to resist

all vertical and lateral forces due to both dead and live loads. Standard

balloon, braced, platform and post and beam types of construction

shall be acceptable framing

methods. Detailed provisions are given for Wood-stud frame. Wall

sheathing. Exterior weather

boarding, veneers and

condensation. Foundation

anchorage, At-grade protection.

Floors, Roofs, Flashing, and

Interior finish. Provisions are given for Integrated assemblies. Splices, and Molded

plywood units.

Shall comply with Appendix B

[Annex A5].

NY State code does

not have specific provisions for wood

construction.

853.1 Requirements for identification of lumber and timber are given in Section 853,1.

Only NYC Building Codes and BOCA

Code have

provisions. Only NYC Building Codes have

provisions.

Only NYC Building Codes have

provisions.

Only NYC Building Codes have

provisions.

126 NISTNCSTAR 1-1 B, WTC Investigation
structural Work

Table 7-3. Structural Work (continued).

NYC Building Code (1968) NYC Building Code (2001)

NY State Building

Construction Code (1964)

1006.6 Empincal

Provisions in lieu of Design

Empincal provisions are given for

certain buildings. The provisions cover Stud walls and partitions. Bracing of exterior walls. Floor and roof framing. Rafter and

ceiling joist, and Built-up members.

27-622 Same

1006.7 Hea\y

Timber

Construction

Provisions for minimum sizes of members and construction details are given.27-623 Same

1006.8 Construction Methods

Provisions for fabrication and

erection are provided.

27-624 Same

Sub-Article 1007.0 Aluminum Article 8 Aluminum

1007.1 General RequirementsMaterials, design and

construction methods shall meet

the requirements ofRS 10-10 [Annex A 1], and RS 10-11 [Annex Al].

27-625 Same

1007.2 Identification 27-626 Same

1007.3 Quality ControlProvisions of Tables 10-1 and

10-2 [Annex Bl] shall apply. Provisions for welding are provided.

27-627 Same

1007.4 Erection Provisions for Bracing. Temporary connections, and

.'Xlignment are provided.

27-628 Same

Sub-Article 1008.0 Reinforced Gypsum Concrete

Article 9 Reinforced Gypsum Concrete

1008.1 General RequirementsMaterials, design, and

construction methods shall meet

the requirements ofRS 10-12 [Annex Al],

27-629 Same

1008.2 Identification of Metal- ReinforcementBundles or rolls of welded wire

fabric shall be securely tagged

so as to identify' the type and

grade of the steel, and the size.

27-630 Same

1008.3 Limitations of UseShall not be used where exposed

directly to the weather or where

subject to frequent or continuous wetting. Precast

units shall be protected from

weather and moisture.

27-631 Same

NISTNCSTAR 1-1B, WTC Investigation 127
Table 7-3

Table 7-3. Structural Work (continued).

Municipal Code of Chicago (1967) BOCA Building Code - Basic Code (1965) Comments

Codes have

provisions.

Only NYC Building Codes have

provisions.

Only NYC Building Codes have

provisions.

724. 0 Light Weight Metals Alummum and other light weight metals and their alloys may be used in the design and construction of buildings or

structures only upon special approval of the building

official, subject to the detennination of the physical

properties by tests as prescribed in Article 8 and in accordance with provisions in section 834.

73-2 Gypsum Concrete 850.0 Reinforced Gypsum concrete

The design and construction of

reinforced gypsum concrete shall be in accordance with the provisions of the Amencan

Standard Specifications for Reinforced Gypsum Concrete.

Shall comply with Appendix B

[Annex A5]. NY State code doesnot have specific provisions for gypsum concrete

construction.

Only NYC Building Codes have

provisions.

Same as in NYC Building Code. Only NYC Building Codes and BOCA

Code have

provisions.

128 NISTNCSTAR 1-1 B, WTC Investigation
structural Work

Table 7-3. Structural Work (continued).

NYC Building Code (1968) NYC Building Code (2001)

NY State Building

Construction Code (1964)

Sub-A rticle 1 009. 0 Thin Shell and Folded-Plate

Construction Article 1 0 Thin Shell and

Folded-Plate Construction

1009.1 General Requirements

.'Applicable reference standards

relating to allowable stress and

the use of structural matenal shall apply.

27-632 Same

1009.2 Analysis Shall be based on assumptions of

elastic behavior. The shell or

plate may be assumed to be homogeneous and isotropic. The

analysis for stability shall consider large deflections, creep

CUIU t lullUll LfW IV^ttll Lilt a\, LUui and theoretical shell surface.

27-633 Same

1009.3 Thin Concrete

Shells The provisions of Sections 403. 404 and 405 of RS 10-45 [Annex

Al] shall apply with the following modifications. The

remaining sections of RS 10-45

shall not apply. ( 1 ) The advisory- provisions of this standard shall be considered mandator^'. (2) Minimum ultimate strength of

concrete for thin shells shall be 3000 psi. (3) Change all references to "the Building Code

(ACl 3 1 8-63)" to "Reference

Standard RS 10-4"

27-634 Same

Sub-A rticle 101 0.0 Suspended Structures

Article 11 Suspended

Structures

1010,1 General Requirements

Shall meet applicable requirements of the code and this section.

27-635 Same

1010.2 Suspenders Provisions for bridge wire cable and other materials are given.27-636 Same

1010.3 Tests of

Materials for Bndge Wire

Suspenders

Provisions on the minimum

quantities of bndge wires to be

tested are given.

27-637 Same

1010.4 Tests of

Materials for Other T\pes

of Suspenders

RS 10-3 [Annex Al] and RS 10-5 [Annex Al] shall apply.

27-638 Same

NISTNCSTAR 1-1B, WTC Investigation 129
Table 7-3

Table 7-3. Structural Work (continued).

Municipal Code of Chicago (1967) BOCA Building Code - Basic Code (1965) Comments

Only NYC Building Codes have

provisions.

Only NYC Building Codes have

provisions.

Only NYC Building Codes have

provisions.

Only NYC Building Codes have

provisions. Only NYC Building Codes have

provisions. Only NYC Building Codes have

provisions.

Only NYC Building Codes have

provisions.

130 NISTNCSTAR 1-1B, WTC Investigation
structural Work

Table 7-3. Structural Work (continued).

NYC Building Code (1968) NYC Building Code (2001)

NY State Building

Construction Code (1964)

1010.5 Design Supplement design requirements

to the applicable provisions for

this article are given for the following topics, (a) Flexibility,

(b) Elastic stretch.

(c) Displacement, (d) Other

considerations (effects of

temperature, wind load, and

vibration) and

(e) Allowable working load. The

allowable working load in suspenders formed from bridge wire cable shall be computed on

the basis of factors equal to (1.5*DL-2.5*LL) or (1.2*DL-2*LL-2*W) applied to the specified, minimum, ultimate

strength of the suspender. The

allowable working load in suspenders conforming to the material specifications of several reference standards of this code

shall be allowable working stress for tension members as prescribed

in the applicable reference standard or, for those materials where allowable stresses for tension members are not

prescribed, on the basis of factors of (1.5*DL-2.0*LL) or (1.2*DL-1.5*LL ^1.5*W), also applied to the specified minimum

ultimate strength of the suspender. In no case, however,

shall the factor, applied to the yield strength of the material or to the prestretching or prestressing

force, exceed (1 .1 'DL-l .25*LL).

27-639 Same

1010.6 Fittings for Wire Cable

Suspenders

Fittings for wire cable suspenders

shall be capable of developing the specified minimum ultimate

strength of the attached cable or

strand without developing the yield stress.

27-640 Same

1010.7 Construction General provisions of RS 10-5 [Annex A 1 ] relating to erection of

steel shall apply.

27-64! Same

1010.8 Protection of Suspenders

27-642 Same

NISTNCSTAR 1-1B, WTC Investigation 131
Table 7-3

Table 7-3. Structural Work (continued).

Municipal Code of Chicago (1967) BOCA Building Code - Basic Code (1965) Comments

Only NYC Building Codes have

provisions.

Only NYC Building Codes have

provisions.

Only NYC Building Codes have

provisions. Only NYC Building Codes have

provisions.

132 NISTNCSTAR 1-1 B, WTC Investigation
Foundations

Table 7-4. Foundations.

NYC Building Code (1968) NYC Building Code (2001)

NY State Building Construction

Code (1964)

Article 11 Foundations Subchapter 11 Foundations

Part 3 Structural Requirements

C302 Soil Bearing I 'alue Sub-A rticle 1100.0 General Article 1 General

100. Scope The provisions of this article shall establish minimum

requirements for the design and

construction of the foundations of buildings.

27-652 Added: Flood areas should comply with RS 4-5 [Annex A2]. Otherwise the same.

100.2 Standards RS 1 1 [Annex .Al] shall be pan

of this article.

27-653 Same C301 Shall be in confonnity with

generally accepted

standards.

1100.3 Definitions See Article 2. 27-654 Same See Section CI 08-3.

1100.6 General RequirementsExcept as othenvise

specifically provided herein, the foundations of buildings

including retaining walls and

other structures shall bear on, or be carried down to. satisfactory bearing materials

in such manner that the entire transmitted load will be

distributed o\ er the supporting

soils at any depth beneath the foundation at unit intensities within the allowable bearing

values established in this

article. In addition, foundations

shall be proportioned to limit settlements to a magnitude that will not cause damage to the proposed construction or to existing adjacent or nearby

buildings during or after construction.

27-657 Same C301

General Requirements

b- Buildings shall be

constructed and integrated so that loads are transmitted

to the soil without undue

differential settlement, unsafe deformation or movement of the bidg or of any structural part, c- Wherever structural material or assemblies are subjected to deterioration and might become

structurally unsound if unprotected, protection in confomiity with generally accepted standards for the material involved shall be

provided. Causes of such

deterioration include, among others, action of

freezing and thawing, dampness, corrosion, wetting and drying, and

termites and other

destructive insects, d- Buildings built in soil which is water bearing at any season of the year shall be constructed so that ground and surface water

will not penetrate into habitable spaces, basements and cellars.

NISTNCSTAR 1-1B. WTC Investigation 133
Table 7-4

Table 7-4. Foundations (continued).

Municipal Code of Chicago (1967) BOCA Building Code - Basic Code (1965) Comments

Chapter 70 Foundations

Article 7 Structural and Foundation Loads

and Stresses

V

See Chapter 47. See Article 2. Some additional

definitions are also given in Section

701.0.

70-1 General Requirements

(a) Every building or structure shall be supported on footings, piles, foundation columns, piers or caissons complying with the requirements of

this section, (b) The encroachment of

foundations on public property shall be governed by section 77-2.1.

700.0 Scope The provisions of this article shall control the structural design of all buildings and structures and their foundations hereafter erected to insure adequate strength of all parts thereof for the safe support of all superimposed live and special loads

to which they may be subjected in addition to their own dead load, without exceeding the allowable

stresses prescribed in the Basic Code or in accepted engineering

practice.

The Chicago Code

addresses encroachment of

foundations on

public property.

134 NISTNCSTAR 1-18, WTC Investigation
Foundations

Table 7-4. Foundations (continued).

NYC Building Code (1968) NYC Building Code (2001)

NY State Building Construction

Code (1964)

1100.7 Depth of Foundations The bottom of any footings and pile caps shall be

carried down at least 4 ft below the lowest level of

the adjoining ground or pavement surface that is exposed to frost. Exceptions to this provision are also given. For grade beams, the bottom of any grade beam

shall be carried down at least 18 in. below the lowest level of the adjoining ground or pavement surface that is exposed to frost.

27-658 Same

1100.8 Foundations at Different LevelsTfie influence of the pressure under the higher

footings on the stability of

the lower footings shall be

considered.

27-659 Same

1 1 00 9 Slabs on Grade Shall be desiiined to limit the settlement of such

slabs.

_ / -oou Same

1 100.10 Constructions The provisions of Anicle

1 9 relating to safety and of

Article 1 0 relating to concrete, timber, masonry,

and steel construction shall apply. For inspection requirements, see Section

1112.0. Provisions for cold weather and seepage are given.

27-661 Same

Sub-Article 1 101.0 Soil Investifiations Article 2 Soil Investigation

1101.1 General Borings in earth or rock, recovery of samples, tests of soil samples, load test, or other investigation or exploratory procedures

shall be performed as necessary' for the design and construction of a safe foundation subject to inspection in accordance

with the requirements of

1112.0.

27-662 Same C302-2

(b)

b- For buildings in which the sum

of snow load and those live loads of all floors which are transferred by columns or walls to the soil, divided by grade-floor area, exceeds 200 psf, there shall be a min of 1 test pit or boring for every 2500 sft of grade-floor area, carried sufficiently into acceptable

bearing materials to establish its character and thickness. Min depth

requirements for at least 1 boring/ 10000 sft are given. Detailed provisions for boring

record requirement are also given.

NISTNCSTAR 1-1 B, WTC Investigation 135
Table 7-4

Table 7-4. Foundations (continued).

Municipal Code of Chicago (1967) BOCA Building Code - Basic Code (1965) Comments

70-3.2 Depth of

Footings

All footings shall be carried to a depth of at least 3 ft 6 in. below the adjoining ground surface, except

that a reinforced concrete slab foundation extending over the

entire area below a one-story

building shall be permitted at a

lesser depth below the adjoining ground surface when so designed as

to eliminate structural damage from

frost action.

729.0 Depth of

Footings

Except when erected on rock or when

otherwise protected from frost, foundation walls, piers and other permanent supports shall extend below the frost line and spread

footings of adequate size shall be

provided to properly distribute the load within the allowable bearing

value of the soil. Or such structures

shall be supported on piles or ranging

timbers when solid earth or rock is not available. No footings shall be founded on frozen soils unless such

frozen condition is permanent.

729.1 Isolated footings. For footings on granular soil of classes 5-10

inclusive in Table 15 [Annex 85], the

line drawn between the lower edges

01 adjoining footings shall not have a

steeper slope than 30" with the

vertical, unless the material supporting the higher footing is laterally supported. 729.2 Floating mat. Shall be located on permanently undisturbed soil. Detailed provisions are given.

70-2.2 Soil Investigation

All applications for building permits shall be accompanied by a statement from the architect or engineer as to the character of the

soil. Where there is reasonable doubt as to the character and

bearing capacity of the soil, the commissioner may require borings,

test pits or test loads.

725.0 Bearing Value of

Soils

All applications for permits for the construction of new buildings or

structures, and for the alteration of a permanent structure which requires changes in foundation loads and

distribution, shall be accompanied by

a statement describing the soil in the ultimate bearing strata, including

sufficient records and data to establish its character, nature and

load-bearing capacity.

136 NISTNCSTAR 1-1 B, WTC Investigation
Foundations

Table 7-4. Foundations (continued).

NYC Building Code (1968) NYC BuUding Code (2001)

NY State Building Construction

Code (1964)

1101.2 Borings

(a) Number. At least one bonng

shall be made for e\ er\' 2500 sft of

building area or fraction thereof

and. for buildings supported on

piling of such t\pe or capacity- that load tests are required, one boring

shall be made for every 1 600 sft of

building area except as indicated in

(1 ) through (3) below. Detailed provisions are given for ( 1

) Oneand nvo-family dwellings. (2) Buildings having a plan area in excess of 1 0.000 sft and where

subsurface meets certain conditions, and (3) Where foundations are to

rest on rock of certain classes. (b) Location. At least 2 3 of the required number of borings shall be

located within the area under the building, those outside shall be

within 25 ft from the limits of the building. Borings shall be uniformly

distributed or distributed in accordance with the loading pattern.

(c) Depth. Provisions for the depth

requirements for the borings are given.

(d) Types. Pro\ isions are gi\'en for

soil borings and rock borings.

(e) Data to be reported. Provisions

are given for data that shall be

recorded and reported.

(f) Disposition of samples and

cores. Soil samples and rock cores

shall be retained in an accessible

location for one year.

27-663 Same

1101.3 Test Pits Test pit may be substituted for borings on a one-for-one basis. All applicable requirements as to depth, number of samples, data to be

reported, and disposition of samples

shall be observ ed.

27-664 Added subdivision (b): provisions for buildings not more than one story in height and for one- or rwo-family residences not more than two stories in height.

NISTNCSTAR 1-1 B, WTC Investigation 137
Table 7-4

Table 7-4. Foundations (continued).

Municipal Code of Chicago (1967)

BOCA Building Code - Basic Code

(1965) Comments

70-2.3 Bonnus All borings shall be made by a procedure that provides info capable of serving as basis for the

classification of the subsurface

materials as specified in 70-2. 1

Detailed requirements for the content of the boring report are given.

726.

726.2

726.3

726.4

When

Required

Soil Samples

Varying

Soil Values

Cost of

Tests

In the absence of satisfactory data from immediately adjacent

areas, the owner or applicant

shall make borings, test pits, or

other soil investigations at such

locations and to sufficient depths of the bearing materials

to the satisfaction of the building official. For all buildings, in other than

residential use groups, which are more than 3 stories or 40 ft in height, and whenever it is proposed to use float, mat or any

type of deep foundation, there

shall be at least one exploratory boring to rock or to a depth of >50 ft below the load-bearing

strata for every 2500 sft of built- over area, and such additional

tests that the building official may direct.

Samples of strata penetrated in

test borings or test pits, representing the natural disposition and conditions at the

site, shall be available for examination of the building

official. Wash or bucket samples

shall not be accepted.

When test borings indicate nonunifonnity of bearing materials,

a sufficient number of additional borings shall be made to establish strata levels of equal bearing capacity.

Tests shall be made by and at the expense of the applicant and

under the supervision of the building official.

138 NISTNCSTAR 1-1 B, WTC Investigation
Foundations

Table 7-4. Foundations (continued).

NYC Building Code (1968) NYC Building Code (2001)

NY State Building Construction

Code (1964)

1101 4 Borings Methods Bonngs shall be made by

continuous driving and cleaning

out of a pipe casing except as permitted in (a) (b) and (c) following. Where casing is used,

it shall be cleaned out to undisturbed soil prior to sampling and the sample spoon driven into

soil that has not been affected by

chopping, washing, or hydrostatic imbalance. Provisions for (a) Uncased borings, (b) Auger

borings, and (c) Maximum

diameter are given.

27-665

1 101.5 Probings and

Geophysical

Explorations

Provisions for the use of

probings, auger bonngs or geophysical methods to substitute borings are given for foundations

consisting of footings or foundation piers or walls bearing on rock of certain classes or

piling bearing on rock of certain

classes. Provisions for geophysical investigation are also given.

27-666 Same

1101.6 Existing BoringsExisting boring data may be

utilized subject to the following:

(1 ) Borings, test pits, probings.

etc.. that have been made in accordance with all requirements of this section, but not

necessarily for the investigation of the specific project for which

application is being made, may

be utilized in fulfillment of these

provisions. (2) The logs of

borings, test pits, probings, etc., that have been made in accordance with all requirements of this section, but wherein the

soil samples and 'or rock cores are not available for examination, may be utilized in fulfillment of

these provisions to an extent not

to exceed 1 '2 of the required number of bonngs. (3) Borings,

test pits, probings, etc.. or the logs thereof that do not meet the

specific requirements of this

article, but which are of suitable type and adequate penetration to provide the data required for the safe design and construction of

the proposed foundation, may be

utilized in fulfillment of the provisions of this section, subject

to the approval of the commissioner

27-667 Same

NISTNCSTAR 1-1 B, WTC Investigation 139
Table 7-4

Table 7-4. Foundations (continued).

Municipal Code of Chicago (1967) BOCA Building Code - Basic Code (1965) Comments

140 NISTNCSTAR 1-1 B, WTC Investigation
Foundations

Table 7-4. Foundations (continued).

NYC Building Code (1968)

NYC Building Code

(2001)

NY State Building

Construction Code (1964)

Sub-Article 1102.0 Foundation Loads

Article 3 Foundation

Loads

1102.1 Soil Beanna

Pressures The loads to be used in computingthe bearing pressures on materials

directly underlying lootings shall be

the total column, pier, or wall

reactions determined in accordance

with the provisions of Article 9. on

the basis of reduced live load; plus

the weight of the foundations; plus

the weight of any soil, fill, and slabs on grade that is included within

vertical planes projected upward

from the extreme limits of the footing to the final ground surface. Live load on grade, or on slabs on

grade, within these limits shall also be included. Impact loads shall be

considered in accordance with

1102.6.

27-668 Same

1 102.2 Pile Reactions The loads to be used in computing

pile reactions shall be determined as provided in 1 102.1. except where

piles penetrate compressible strata, the pile load shall be increased by

the amount of drag exerted by such matenal during consolidation. Provisions for the computation of

the drag are given.

27-669 Same

1102.3 Lateral Loads Provisions for (a) Earth and ground

water pressure, (b) Wind and other superstructure loads, and (c) Soil movements are given.

27-670 (a) Earth and ground

water pressure; Added

provisions for earthquake forces acting on the retaining

wall.

1102.4 Eccentricities Provisions for eccentncity of

loading in foundations are given.

Soil pressure and pile load due to eccentricity shall be computed on

the basis of straight line distribution of foundation reaction, or other modes of distribution with demonstrable evidence.

27-671 Same

1102.5 Uplift Forces Uplift and overturning forces due to wind and hydrostatic pressure shall be considered.

27-672 Same C304-5

C304-7

Overturning

Uplifting Overturning and uplifting forces due to wind or

hydrostatic head shall be

considered. Detailed

provisions of these two

sections can be found in Table B of this report.

1102.6 Impact Load May be neglected in the design of

foundations, except for foundations on loose soil, or those supporting

hea\'y impact loads.

27-673 Same

1102.7 Stability Provisions in 1 1 1 1 .0 shall apply. 27-674 Same

NISTNCSTAR 1-1 B. WTC Investigation 141
Table 7-4

Table 7-4. Foundations (continued).

Municipal Code of Chicago (1967)

BOCA Building Code - Basic Code

(1965) Comments

\

710.1 Below

Grade

All retaining walls and other walls below grade shall be

designed to resist lateral soil pressures with due allowance for hydrostatic pressure and for all superimposed vertical loads.

710.2 Hydrostat

ic Uplift

All foundation slabs and other

footings subjected to water

pressure shall be designed to

resist a unifonnly distributed

uplift equal to the full hydrostatic pressure.

Only NYC

Building Code

considers impact

loads.

142 NISTNCSTAR 1-1B, WTC Investigation
Foundations

Table 7-4. Foundations (continued).

NYC Building Code (1968)

NYC Building

Code (2001)

NY State Building Construction Code

(1964)

103.4 Allowable

Soil Bearing

Pressures

The allowable bearing pressures on

satisfactory' beanng matenals shall be

those established in Table 1 1-2 [Annex Bl]. The allowable bearing

pressures on nominally unsatisfactory bearing matenals shall be those

established in accordance with C26-

1 103.5. Allowable beanng pressure

shall be considered to be the allowable pressure at a point in the

soil mass in excess of the stabilized overburden pressure existing at the same point prior to construction

operations. TTie stabilized overburden

pressure existing at a point shall be

defined as that portion of the weight

of the overlying soil material that is supported by granular interaction rather than pore pressure. In general,

the magninide of the stabilized overburden pressure may be approximated as follows:

(a) The overlying soil material shall be in place for an adequate length of

time. Where the bearing stratum

consists of soils of classes 5-65 through 8-65. the bearing stratum

shall be considered to be fully consolidated.

(b) The weight of fill material shall not be included in the stabilized overburden pressure unless its magnitude of stabilized pressure is verified by tests. (c) Where the bearing stratum consists of soils of classes 9-65 through 1 1 -65,

the stabilized overburden pressure

shall be taken as zero unless its magnitude is verified by tests. (d) The stabilized o\ erburden

pressure shall not include the weight

of any soil removed by excavation and not replaced. For footings, the

stabilized overburden pressure shall not exceed the weight of 1 sft column

of soil measured from the bottom of

the footing to the lowest level of the

final grade above the footing. For a boxed foundation, the pressure shall not exceed the weight of 1 sft column

of soil measured from the bottom of

the box to the lowest level of the adjacent grade.

(e) Where the bearing stratum consists of soils of classes 9-65 through 1 1-65,

the allowable bearing pressure shall be adjusted for the effects of rebound

due to excavation.

(f) Where the bearing stratum consists of rock of classes 1-65 through 3-65.

the stabilized overburden pressure

shall be neglected.

27-678 Same C302-1

General

Require- ment

C302-2

Deter- mination

The bearing value of the soil shall be detennined in order that foundations may be proportioned so as to provide a min of absolute and differential settlement. Soil or pile tests, presumptive bearing values of the soil, reduction factors for pile groups, and

pile driving formulas, referred to in this Code, shall be in conformity with

generally accepted standards. When it can be conclusively proved that the presumptive soil bearing value is adequate for the proposed load, the enforcement officer may accept such proof in lieu of the determination

prescribed in C302-2b.

a- For buildings in which the sum of snow load and those live loads of all the

floors which are transferred by columns

or walls to the soil, divided by gradefloor area, is 200 psf or less, the allowable bearing value of the soil shall be the presumptive bearing value, or

shall be determined by field load tests, b- For buildings in which the sum of snow load and those live loads of all floors which are transfened by columns

or walls to the soil, divided by

grade-floor area, exceeds 200 p.sf, there

shall be a min of 1 test pit or boring for every 2500 sft of grade-floor area, carried sufficiently into acceptable bearing materials to establish its character and thickness. Min depth requirements for at least 1 boring/10000

sft are given. Detailed provisions for boring record requirement are also given.

c- For buildings referred to in C302-2b, when the bidg load is transferred to the

soil by spread footings, the allowable bearing values of the successive layers of soil detennined by test pit or boring

shall be the presumptive bearing values

and, if required, shall be substantiated by field loading soil tests made on

undisturbed, natural soil at the level of

the proposed foundation, with fill, if any, removed.

d. For buildings referred in C302-2b, when the load is transferred to the soil through the medium of friction or bearing piles, the capacity of a pile group shall be the number of piles multiplied by the capacity of 1 pile and by a reduction factor for friction piles. The capacity of a pile shall be determined by either a field loading pile

test or a generally accepted pile-driving formula or a combination of both, with a

limit determined by the strength of the

pile as a structural member.

NISTNCSTAR 1-1 B, WTC Investigation 143
Table 7-4

Table 7-4. Foundations (continued).

Municipal Code of Chicago (1967)

BOCA Building Code - Basic Code

(1965) Comments

70-2.4 Soil Bearing Values Maximum allowable pressures on the supporting soils at the bottom of the footings shall not exceed the values

in Table 70-2.4 (a) [Annex B4]

except when determined by tests or

analysis. Exceptions to allowable bearing

values; (1 ) Variation in soils. Where

portions of the foundations of the same structure rest upon soils which

vary substantially in bearing value,

special provisions shall be made to prevent serious differential settlements which will impair the

safety of the structures. (2) Where the bearing materials directly under a foundation overlie a stratum having

smaller allowable bearing values, these smaller values shall not be exceeded at the level of such stratum. Computation of the vertical pressure

in the bearing materials at any depth below a foundation shall be made on

the assumption that the load is spread unifomily at an angle of sixty degrees

with the horizontal. (3) Subject to the approval of the commissioner of

buildings, bearing values greater than

those required in 70-2.4 may be used

if analysis based on laboratory tests, field loading tests or other pertinent information demonstrate that the greater values will not lead to excessive settlement.

725.2 Presumpti ve

Bearing Values

Except when determined by

field loading tests or as otherwise provided herein, the max allowable pressure on

supporting soils under spread

footings at or near the surface

shall not exceed the values

specified in Table 15 [Annex

B5]. Pre.sumptive bearing values

shall apply to all materials of

similar physical characteristics and disposition. Surface values

shall be adjusted for deep

footings and for the bearing

strata under piles as provided in the Basic Code. When

foundation caissons are driven

to penetrate into sound rock, the allowable bearing values in Table 15 [Annex B5] may be

increased as prescribed in Section 744.

144 NISTNCSTAR 1-1 B, WTC Investigation
Foundations

Table 7-4. Foundations (continued).

NYC Building Code (1968) NYC Building Code (2001)

NY State Building

Construction Code (1964)

1 103.5 Bearing Capacity of Nominally

Unsatisfactory Bearing Materials

A report based on soil tests and

foundation analysis shall be submined demonstrating that the proposed construction, under a condition of 1 DO % overload, is safe against failure of the soil materials. The report shall also show that the probable total magnitude and

distribution of senlement to be

expected under design conditions will not result in instability of the building

or stresses in the structure in excess of the allowable values established in Anicle 10. In addition, the following

provisions shall apply:

(a) Fill materials. Provisions for controlled fills and uncontrolled fills are given, (b) Organic silts. Organic

clays. Soft Inorganic clays. Loose

inorganic silts, and Var\'ed silts. Provisions for determining the allowable bearing pressure for the aforementioned materials are given. Also, the report required in this section shall include information regarding the geological profiles through the area, sufficient test data on the compressible material, cross

sections showing the amount of fill and surcharge, the estimated amount

and rate of settlement, and detailed analysis showing that the anticipated

future settlement will not adversely

affect the performance of the

structure.

27-679 Same

1 103.6 Utility Serv ices Provisions are given to prevent damage to the utility serv ice lines laid

in soil materials.

27-680 Same

Suh-Anicle 11 04.0 Soil Load Bearing Tests

Article 5 Soil Load Bearing

Tests

1 104.1 Applicability Soil load beanng tests may be

accepted as evidence of allowable

bearing capacity of a given soil stratum, subject to the following

limitations: (a) The applicability of

soil load beanng tests shall be limited

to soil materials of classes 5-65 through 10-65. (b) Soil load bearing

tests shall not be used to justify allowable beanng pressures in excess of the maximum allowable bearing values in Table 1 1-2 [Annex Bl]. (c) Soil bearing tests shall not be

applicable where the propo.-ied bearing stratum is underlain by a stratum of lower class, unless

analysis indicates that the presence of

the lower class will not create excessive settlement.

27-681 Same

NISTNCSTAR 1-1 B, WTC Investigation 145
Table 7-4

Table 7-4. Foundations (continued).

Municipal Code of Chicago (1967) BOCA Building Code - Basic Code (1965) Comments

725.3 Light Weight

Structures

Mud. organic silt, or unprepared

fill shall be assumed to have no

presumptive bearing capacity

unless approved by test, except where the bearin'g capacity is deemed adequate by the building

official for the support of light weight and temporary structures.

Only NYC

Building Codes

have provisions to prevent damage to

utility services.

70-2.5 Field Loading Tests 72 7. 0 Soil Test Procedure

(a) Whenever the bearing value of

soil is in reasonable doubt or when

it is desired to use soil bearing

values in excess of those

established in Table 70-2.4(a) [Annex Bl], the allowable load on

a bearing material may be determmed by test in accordance

with the requirements of this section.

146 NISTNCSTAR 1-1B, WTC Investigation
Foundations

Table 7-4. Foundations (continued).

NYC Building Code (1968)

NYC Building Code

(2001)

NY State Building Construction Code

(1964)

1104.; Procedure Pro\ isions are given for Preparation. Loading of the soil and Determination of results.27-682 Same C302-3

Performance

Criteria for Field Loading Soil Test

C302-4

Performance

Criteria for

Pile Test

Under field loading test, the total settlement caused by the proposed

load on the soil, measured after a period during which no settlement had occurred for 24 hrs. shall not exceed 3/4 in. The additional settlement caused by a 50 %

increase in the proposed load, measured after a period during which no settlement had occurred

for 24 hrs. shall not exceed 60 % of

the total settlement as previously measured under the proposed load.

a- The test load shall be twice the proposed pile load, applied in increments of 1/4 of the proposed

pile load, with readings of

settlements taken to the nearest 1/32

in. and plotted against load. The test load may be increased to more than

tw ice the proposed pile load value

until the gross settlement is approximately 1 in. At each step the load shall remain unchanged until there is no settlement m a 2 hr period, and the test load shall remain in place until there is no

settlement in 48 hrs. b- The total test load shall then be removed in decrements not exceeding 1/4 of the total test load

at intervals of not less than Ihr. with rebound read after each removal of

load and plotted against load and

with the final rebound recorded 24

hrs after removal of the last decrement. The allowable pile load

shall be the lesser of 1/2 of that load which caused a gross settlement of 1

in. or a net settlement equal to 0.01

in. /ton times total test load in tons, with a limit determined by the strength of the pile as a structural member.

Sub-Article 1105.0 Footings, Foundations

Piers, and Foundation M alls

Article 6 (Same title as in '68 Code)

1 105.1 Matenals All structural elements of

foundations shall meet the requirements as to type and minimum quality of matenals

prescribed in Article 10.

27-683 Same

NISTNCSTAR 1-1 B, WTC Investigation 147
Table 7-4

Table 7-4. Foundations (continued).

Municipal Code of Chicago (1967)

BOCA Building Code

(1965)

Basic Code

Comments

(b) Test procedure. (1 ) A sufficient number of tests shall be made to determine the bearing value of the

soil over the entire building site. (2) Each load test area shall be no less than 4 fr. except that for soils of > 10,000 psf bearing capacity, the area can be 1 ft^. (3) Load increments shall not exceed 25 % of the proposed safe load until the load reaches 200 % of

it. (4) The load increment shall be

applied at unifonn intervals such that the proposed safe load is reached m

>8 hrs. This load shall remain until no measurable settlements shall occur

in 1 6 hrs period. The total test shall then be completed in >8 hrs. The total load shall remain until no measurable

settlement occurs in 16 hrs. (5) Measurements of settlement shall be

recorded diagrammatically.

(c) Conditions of acceptance. (1 ) The

total settlement under the proposed

safe load shall not exceed 3/8 in., and

the total settlement under double the design load shall not exceed 1 in. (2) The proposed safe load shall not cause pressure on any underlying soil stratum in excess of maximum

pressures established in Table 70-

2.4(a). If the above conditions are not

satisfied, the allowable safe load shall be detennined by selecting a reduced

load from the load-settlement diagram such that the above

conditions are satisfied.

727.1

727.2

727.3

727.4

727.5

Soil Test Method

Loaded

Area

Recorded

Settlements

Accuracy

of Loading

Test Acceptance

The test procedure and testing apparatus shall be approved by

the building official before they

are used; and a complete record of the tests together with a record of the soil profile shall be filed by the licensed engineer or architect who shall have a fully qualified representative on the site during all boring and test operations.

For spread footings, the soil shall be loaded at one or more

places and at the required level or levels. The loaded area shall be approximately 4 sft for all bearing materials; except that when the footing overlies wet

clay or other soft materials, the

test load shall be applied to an

area of not less than 1 0 sft.

Loads shall be applied in continuous increments of not more than 1/4 of the proposed

safe load. When the proposed

load has been reached, it shall remain undisturbed and

readings shall be recorded to determine the rate of settlement

until the settlement in 8 consecutive hrs is less than

0.01 in. A 50 % excess load

shall then be applied and

allowed to remain in place until the rate of settlement is less than 0.01 in. in 24 hrs.

Test loads applied by

mechanical devices shall be

automatically controlled so

as to insure not more than 5 %

variation m applied load. Such

devices shall be calibrated prior

to the test.

The load settlement shall be

represented diagrammatically, and no test shall be deemed

satisfactory if the net settlement

after removal of the test load exceeds 0.01 in./ton of gioss

load applied.

148 NISTNCSTAR 1-1B, WTC Investigation
Foundations

Table 7-4. Foundations (continued).

NYC Building Code (1968) NYC Building Code (2001)

NY State Building

Construction Code (1964)

1105.2 Footings (a) Wood footings. May only be used for wood frame structures. Preser\ative treatment shall be

in accordance with RS 1 1 -4 [Annex Al].

(b) Pole buildings. Buildings not more than one story high may

be supported on poles embedded

in the ground. Shall have

protecti\ e treatment for wood

and steel poles.

(c) Grillages. Shall have proper

spacers, stiffeners. and

diaphragms, or spaces between beams shall be filled with

concrete and grout.

(d) Design. ( 1 ) Concrete

footings; per RS 10-3 [Annex

A5]. Reinforcement shall extend

to within 4 in. of the edges of

the footings. (2) Masonry

footings; Reinforced masonry

footings shall meet the requirements of RS 10-2 [Annex

A5] and shall be proportioned

similarly to the proportioning of RC footings. Provisions are also given concerning the dimensions of unreinforced masonry footings.

Same

NISTNCSTAR 1-1 B, WTC Investigation 149
Table 7-4

Table 7-4. Foundations (continued).

Municipal Code of Chicago (1967) BOCA Building Code - Basic Code (1965) Comments

70-3 Footings Footings shall be provided under walls, piers or columns

where required to distribute their loads in accordance with the allowable beanng values of the supporting soils as provided in Section 70-2.

70-3.1 Proportioning. Footings

shall be so proportioned as to insure a min. of unequal

settlement. 70-3.2 Depth. All footings shall be carried to a depth of at least 3

ft 6 in. below the adjoining ground surface, except that a RC

slab foundation below a onestory buildmg shall be permitted

at a lesser depth. 70-3.3 Construction, (a) General. Footings shall be

constructed of solid masonry or

concrete with or w/o

reinforcement and shall be so designed that stresses in the material shall not exceed the maximum allowable stresses required in the following

chapters: RC footings (Chap

73), plain concrete footings (Chap. 71. 73), masonry

footings (Chap. 71). (b) Masonry footings. Footings

constructed of solid masonry

units shall have a depth at least twice the total projection beyond the wall or column base. When bnck work in foundation

walls is stepped to form a

footing, the maximum offset for each course shall be

1 .5 in. (c) Steel grillage footings. When structural steel members are used in footing construction, such members shall be entirely encased by at least 3 in. of

concrete, and the space between

the members shall be entirely

filled with cement grout. Stress in steel members shall not exceed the allowable stress required in Chap. 74.

730.0

731.0

732.0

733.0

734.0

735.0

736.0

Footing

Design

Timber

Footing

Steel Grillages

Linrein- forced Concrete

Footings

Masonry

Unit

Footings

Reinforced Concrete

Footings

Mat. Raft and Float Foundations

730.1 Design loads. The full dead load including

the weight of foundations, footings, and

overlying fill and reduced LL shall be used. 730.2 Pressure due to lateral loads (W, E).- May

be neglected if <I/3 of the DL-i-LL pressure

alone. If > 1/3. such increased pressure shall be

considered with a 1/3 increase in allowable soil pressure under the combined load. 730.3 EQ loads. Shall comply with Section

719.0. 730.4 Vibratory loads. Consideration shall be

given to the design of the footings to prevent

detrimental disturbance of the soil. 731-1 Where permitted. Only for wood frame

structures unless otherwise approved by Building

Official. Shall be placed entirely below the pennanent water level except when treated. 2.- Untreated timber.- The compressive stresses perpendicular to the grain in untreated timber

footings shall not exceed 70 % of the allowable

stresses of the specified lumber. 732.0 Shall be separated with approved steel spacers and shall be entirely encased

in at least 3 in. of concrete and the spaces between the beams shall be filled with concrete

or cement grout. When used on yielding soils, steel grillages shall rest on approved concrete beds >6 in. thick. 733- 1 . Concrete strength.- Not less than 2000

psi at 28 days. 2. Deposition.- Shall not be poured through water unless otherwise approved

by the building official. When poured under or in the presence of water, the concrete shall be

deposited by approved means, which insure minimum segregation of mix and negligible turbulence of the water. 3. Dimensions. Edge

thickness shall be not less than 8 in. for footings on soil, and not less than 12 in. above the tops of

piles for footings on piles. Except: May be reduced to 6" and 8" respectively for 1 -story and basement buildings of wood frame or brick veneered walls. 4. Protection.- Shall be protected from freezing during deposition and not less than

5 days thereafter and no water shall be allowed to fiow through the concrete. 734- 1 Dimensions: Shall be laid in Type M or S

mortar complying with Section 816. Provisions

for depth and width of the wall are also given.

2 . Offsets: Provisions for maximum offset of each

course laid in single or double courses are given. 735- 1. Design: Shall comply with Sections 841, 842, 843, 844 and applicable standards in Appendix B [Annex A5]. 2. Dimensions: Edge

thickness shall be not less than 5 in. above the

reinf. if on soil, and not less than 12 in. if on

piles. Provisions for dimensions of pile caps are

also given. 3. Protection. When concrete is deposited directly against the ground, the reinf. shall have a minimum cover of 3 in. At other

surfaces of foundation concrete, the minimum

cover shall be 2 in. 736.0 Shall be used only when the loading is unifonnly balanced and the soil immediately below the mat is of uniform bearing capacity*.

The BOCA

Building Code

has the most

comprehensive

footing design

provisions.

150 NISTNCSTAR 1-1B, WTC Investigation
Foundations

Table 7-4. Foundations (continued).

NYC Building Code (1968) NYC Building Code (2001)

NY State Building

Construction Code (1964)

1105.3 Foundation

Piers

Shall be designed as columns. RC piers shall conform to RS 10-3 [Annex A5]. Reinforced and unreinforced masonry piers shall conform to RSI 0-2 [Annex A5] and RS 10-1 [Annex A5].

respectively. Unreinforced

concrete piers shall conform to C26-1 105.3 (b). (a) Lateral support. May be

determined by elastic analysis, or a pier may be assumed to be

hinged, but laterally braced at intern als equal to the full height of the pier or eight times the

least dimension of the pier, whichever is the lesser value. Provisions in 1 105.3 (e) shall apply.

(b) Unreinforced concrete piers. Provisions for the allowable compressive stress, the ratio of

height to the least lateral dimensions, and maximum

eccentricity are given.

(c) Metal shells. Where piers are encased by a metal shell, provisions for when the shell can be considered as contributing to the structural strength of the pier are given.

(d) Minimum dimensions.

Provisions for pier dimensions

are given.

(e) Filling. The provisions of (a) and (d) shall apply only where

the fill is placed around the pier as controlled fill. For

uncontrolled fills, provisions are given for the dimensions of the

piers.

27-685 Same

NISTNCSTAR 1-1 B. WTC Investigation 151
Table 7-4

Table 7-4. Foundations (continued).

Municipal Code of Chicago (1967) BOCA Building Code - Basic Code (1965) Comments

70

-12

Foundation Columns

70-12 Foundation columns: shall consist of steel pipe shells extending to rock and

completely filled with concrete with or w/o steel reinforcement or cores. 70-12.1 The pipe shall confomi to ASTM specifications for welded and

seamless steel pipe piles and shall have a minimum thickness of 0.3 in. The

nominal diameter of pipe shall be not

less than 22 in. 70-12.2 Foundation column shall extend

to solid rock as defined in Section 70-

2.1. 70-12.3 Allowable load and stresses, (a) If the base of the foundation column is less than Ift below the surface of the

solid rock, the bearing load on solid rock

shall not exceed 100 tsf or the value determined by tests as provided in Section 70-2.5. (b) If the base of

foundation column is ! ft or more below

the surface of the solid rock, the allowable bearing value may be

increased 20 %/ft for each foot of depth

greater than 1 ft, but shall not exceed 200 tsf (c) When the column extends through a layer of unstable soil, the maximum design load shall be computed

as for a column with an unsupported

length equal to the depth of the unstable

layer of soil, plus 4 times the diameter of

the column.

749.0 Foundation

Piers

1 . Unreinforced; when the unsupported height of

foundation piers exceeds 6 times the least dimension, the allowable working stress on piers of unit masonry or plain concrete shall be reduced

in accordance with accepted engineering practice.

2. Reinforcement: 1 ) Design- May be reinforced with spiral or vertical reinf in accordance with

provisions of column design in Appendix B

[Annex A5]. When adequate lateral support is provided, the requirements for long column shall be waived. 2) Minimum percentage: An outer

peripheral ring of a thickness of 1/10 of the pier perimeter, but not to exceed 2'. shall be considered

an envelope. Based on the area of such envelope,

the min. vertical reinf shall be 3/4 of 1 % and

2/10 of 1 % of horizontal reinf throughout its length. Minimum concrete cover shall be 3".

3. Steel shells: When concrete piers are entirely encased with a circular steel shell, the area of the

shell steel may be considered as reinforcing provided it is protected per 738.0. All horizontal

joints in the shell shall be spliced per Section 737,

4. Dimensions: Minimum dimension for isolated

pile: 2'. height< 12 times the least dimension

unless it's RC or steel or encased in steel shell>l/4" thick. Greater length may be approved

if adequate lateral support exists.

5. Belled bottoms: The edge thickness of the bell shall be >12" and the side of the bell shall slope at >60" to the horizontal.

6. Dewatering: Shall insure accurate preparation and inspection of the bottom and the deposition or construction of sound concrete in the dry.

70

-13

Foundati on Piers and

Caissons

Shall be of concrete w/ or \v/o steel reinforcement, extending to solid rock or

to hardpan.

70-1 3.1 Piers or caissons bearing on

hardpan may be belled to increase load carrying capacity, provided that such

bell shall be at least 12 in. thick at its edge and that the sides shall slope at an angle of not less than 60" with the horizontal. 70-13.2 Allowable load and stress, (a) The allowable bearing value shall be the bearing capacity of the hardpan or rock

as in section 70-2.4. (b) The load used in determining the areas of the piers and of

the belled bottom shall be the load supported at the top of the pier. 70-13.3 Tests, (a) Where piers are to be supported on hardpan. the thickness of

the hardpan strata shall be determined by

boring extended not less than 6' below

the bottom of the pier, (b) When piers extend to bedrock, the thickness of the rock strata shall be detennined by

borings extended not less than 8 ft into solid rock. The rock bottom of not less than 1 0 % of the total number of piers evenly distributed over the site shall be

so drilled.

152 NISTNCSTAR 1-1 B, WTC Investigation
Foundations

Table 7-4. Foundations (continued).

NYC Building Code (1968) NYC Building Code (2001)

NY State Building Construction

Code (1964)

1105.4 Foundation Walls

(a) Concrete.- Shall be

designed according to RS \0-3 [Annex A5].

Provisions for equivalent unbraced height are given.

(b) Masonr\'.- Provisions for the tv'pes and wall thickness

are given. In addition, provisions in RS 10-1 [Annex A5] and RS 10-2 [Annex A5] should be

followed.

27-686 Same

1105.5 Construction of

Footings. Foundation

Piers, and

Foundation

walls

Provisions of 1 1 00. 1 0 and

11 12.5 shall apply. In addition, provisions are given for conditions that shall be satisfied for the methods of installation and

construction.

27-687 Same

Sub-Article 1 106.0 Pile Foundations-General

Requirements

Article 7 (Same title as in '68 Code)

1 106.1 Administrative RequirementsRequirements concerning

Identification of piles and Record of pile dnving are given.

27-688 Same

1106.2 Mmimum Pile Penetrations

(a) Required by soil bearing

capacity- 1107.1 (b)(1) shall apply.

(b) Required for lateral restraint- 1 106.7 shall apply.

(c) Piles located near a lot line- provisions are given.

27-689 Same

1106.3 Use of Existing

Piles at Demolished

Structures

Requirements for piles at demolished sites to be used

for the support of new

constructions are given.

27-690 Same

1 1 06.4 Tolerances and

Modification of Design due to Field Conditions

Provisions are given for the tolerance in alignment of

the pile axis, tolerance in location of the head of the

pile, and Bent piles.

27-691 Same

NISTNCSTAR 1-1 B, WTC Investigation 153
Table 7-4

Table 7-4. Foundations (continued).

Municipal Code of Chicago (1967) BOCA Building Code - Basic Code (1965) Comments

871.0 Foundation Walls

Design: Foundation walls shall be designed to resist frost action and

to support safely all vertical and

lateral loads as provided in Article

7. The maximum stresses due to combined load shall be within the values specified for the materials used in the construction. Unless

nrnnprlv rpinforrpfl tprriilp Stresses shall not exceed those

permitted in plain masonry.

Provisions for minimum thickness of foundation walls of various

materials are also given.

Pile Foundations - General Requirements Pile Foundations

737.0 Pile FoundationsShall be designed to transmit loads

to lower strata of foundation

materials. The bearing value of the supporting soil shall be evaluated

per Section 739. Piles may be

constructed of any approved

matenals.

737.1 Site Investigation The building site shall be

investigated for all conditions which might promote deterioration of the pile foundations, and

approved protective measures shall be taken.

737.6 Minimum

Length and

Penetration

Provisions for piles near lot line are given.

Only NYC Building Code has this provision.

737.9 Precautions During driving, all piles shall be

held in their design location and

shall be dnven plumb. Tolerance to

lateral deviation of the pile is given. Driving shall be under inspection.

154 NISTNCSTAR 1-1B, WTC Investigation
Foundations

Table 7-4. Foundations (continued).

NYC Building Code (1968) NYC Building Code (2001)

NY State Building Construction

Code (1964)

1106.5 Minimum

Spacing of

Piles

Provisions for the minimum

pile spacing are given.

27-692 Same

1 106.6 Minimum

Section

Provisions for the minimum

pile sections are given.

27-693 Same

1106.7 Capping and

Bracing of

Piles

(a) Capping of piles.

Provisions are given for pile embedment, uplift, reinforcement, and design.

(b) Bracing of piles.- Except

for short piles, provisions are given for the lateral bracing of piles with caps, brace beams, concrete slab-ongrade. other means (anchors), and floor system. Special requirements for bracing baner piles are also given.

(c) Bracing of short piles.

Provisions for bracing of

short piles are given.

27-694 (c) Bracing of short piles,

( 1 ) Added, at the end of the paragraph, provisions for depth for pile penetration. Otherwise, the same.

1106.8 Splicing of

Piles

Provisions for splicing of

piles are given.

27-695 Same

1106.9 General Requirements

for

Installation of Piles

(a) Protection of adjacent

property, (b) Protection of the

pile during installation, (c) Protection of pile materials

after installation. Specific provisions are given for untreated timber piles and

piles installed in ash or garbage fills etc that need

special protection,

(d) Equipments for pile

installation.

27-696 Same

1106.10 Use of Uncased

Concrete Pile Shafts

Conditions where uncased

shafts can be used are given

for bored piles and dnven

piles.

27-697 Same

NISTNCSTAR 1-1 B. WTC Investigation 155
Table 7-4

Table 7-4. Foundations (continued).

Municipal Code of Chicago (1967) BOCA Building Code - Basic Code (1965) Comments

70-4 (a) Minimum

Spacing

Provisions for minimum

spacing are given.

737.2 Spacing The minimum C-C spacing of piles

shall not be less than twice the rliamptpr at a roiinn nilp nnr Ipqq than 1.75 times the diagonal dimension of a rectangular pile. When driven to rock, the spacing

shall be not less than 24 in. When

other than rock, the spacing shall not be less than 30 in. For piles which

cannot be checked for plumbness, the minimum spacing prescribed herein

shall be increased not less than 6 in.

737.5 Minimum

Dimensions

Provisions for tapered piles and

uniform circular and non-circular

sections are given.

70-4 (b) Pile Caps Provisions for pile caps are given.737.3

737.4

Wall Piers

Isolated Pier

Piles

Piles in wall foundations shall be

staggered about the C-line at a min.

distance of 1 /2 the top diameter. Exceptions for single row are given.

Not less than 3 piles shall be

furnished under isolated piers, unless

lateral bracing is provided.

737.7 Splices Shall be avoided if possible. Where

used, splices shall be such that the

resultant vertical and lateral loads at the splices are adequately

transmitted. Detailed provisions are given.

738.0 Corrosion

Protection

1. Preservative treatment. Shall comply with Section 740.5 and Appendix C [Annex A5]. 2. VL'eiClCU^. J. 1 1 UlCCU VC JaCPvCli. When surrounding soil contains

destructive chemical elements,

protective jacket shall be provided. When the jacket is of concrete, the thickness of the cover shall be not

less than 1 .5 in. 4. Cinder fill: Shall be considered sufficient reason for protective jacket.

156 NISTNCSTAR 1-1B, WTC Investigation
Foundations

Table 7-4. Foundations (continued).

NYC Building Code (1968) NYC Building Code (2001)

NY State Building Construction

Code (1964)

1106.5 Minimum

Spacing of

Piles

Provisions for the minimum

pile spacing are given.

27-692 Same

1106.6 Minimum

Section

Provisions for the minimum

pile sections are given.

27-693 Same

1106.7 Capping and

Bracing of

Piles

(a) Capping of piles.

Provisions are given for pile embedment, uplift, reinforcement, and design.

(b) Bracing of piles.- Except

for short piles, provisions are given for the lateral bracing of piles with caps, brace beams, concrete slab-ongrade, other means (anchors), and floor system. Special requirements for bracing

batter piles are also given.

(c) Bracing of short piles.

Provisions for bracing of

short piles are given.

27-694 (c) Bracing of short piles,

( 1 ) Added, at the end of the paragraph, provisions for depth for pile penetration. Otherwise, the same.

1106.8 Splicing of

Piles

Provisions for splicing of

piles are given.

27-695 Same

1 106.9 General Requirements

for

Installation of Piles

(a) Protection of adjacent

property, (b) Protection of the

pile during installation, (c) Protection of pile materials

after installation. Specific provisions are given for untreated timber piles and

piles installed in ash or garbage fills etc that need

special protection,

(d) Equipments for pile

installation.

27-696 Same

1 106.10 Use of Uncased

Concrete Pile Shafts

Conditions where uncased

shafts can be used are given

for bored piles and driven

piles.

27-697 Same

NISTNCSTAR 1-1 B, WTC Investigation 157
Table 7-4

Table 7-4. Foundations (continued).

Municipal Code of Chicago (1967) BOCA Building Code - Basic Code (1965) Comments

70-4 (a) Minimum

Spacing

Provisions for minimum

spacing are given.

737.2 Spacing The minimum C-C spacing of piles

shall not be less than twice the diameter of a round pile, nor less than 1 .75 times the diagonal dimension of a rectangular pile. When driven to rock, the spacing

shall be not less than 24 in. When

other than rock, the spacing shall not be less than 30 in. For piles which

cannot be checked for plumbness, the minimum spacing prescribed herein

shall be increased not less than 6 in.

737.5 Minimum

Dimensions

Provisions for tapered piles and

unifomi circular and non-circular

sections are given.

70-4 (b) Pile Caps Provisions for pile caps are given.

737.3

737.4

Wall Piers

Isolated Pier

Piles

Piles in wall foundations shall be

staggered about the C-line at a min.

distance of 1/2 the top diameter. Exceptions for single row are given.

Not less than 3 piles shall be

furnished under isolated piers, unless

lateral bracing is provided.

737.7 Splices Shall be avoided if possible. Where

used, splices shall be such that the

resultant vertical and lateral loads at the splices are adequately

transmitted. Detailed provisions are

738.0 Corrosion

Protection

1 . Preservative treatment. Shall comply with Section 740.5 and Appendix C [Annex A5]. 2. (Deleted). 3. Protective jackets. When surrounding soil contains

destructive chemical elements,

protective jacket shall be provided. When the jacket is of concrete, the thickness of the cover shall be not

less than 1 .5 in. 4. Cinder fill: Shall be considered sufficient reason for protective jacket.

158 NISTNCSTAR 1-1 B, WTC Investigation
Foundations

Table 7-4. Foundations (continued).

NYC Building Code (1968) NYC Building Code (2001)

NY State Building Construction

Code (1964)

1106.11 Where More

Than One Pile Type.

Pile Capacity,

or Method of

Pile

Installation Is Used

The sev eral parts of the building supported on the

different types, capacities, or modes of piling shall be

separated by suitable joints providing for differential movement, or a report shall be submined showing that the proposed construction is adequate and safe.

27-698 Same

1106. 12 Pile Matenals The provisions of C26-

1000.1 and 1000.9 relating to "classification of materials, assemblies and methods of

construction" and to the use of "used and unidentified matenals" shall apply.

27-699 Same

NISTNCSTAR 1-1B, WTC Investigation 159
Table 7-4

Table 7-4. Foundations (continued).

Municipal Code of Chicago (1967) BOCA Building Code - Basic Code (1965) Comments

748.0 Lateral Support1 . Surrounding materials: Any soil other than water or fluid soil shall be deemed to afford sufficient lateral support to pennit the design of any

type of pile as a short column. When

piles are driven through soil which

will be removed subsequently to the completion of the foundation, the resistance offered by such material

shall not be considered to contribute

to the lateral supporting capacity.

2. Fixed ends: When not assumed

laterally supported by the surrounding soils and when fixed by

lateral supports at the upper end

only, the unsupported length of pile or other isolated foundation shall be assumed as 3/4 the total length: and when supported at the bottom by

drilling or other rigid attachment into the bed rock in addition to top lateral support, the unsupported length shall be assumed as 1/2 the total length.

160 NISTNCSTAR 1-1B, WTC Investigation
Foundations

Table 7-4. Foundations (continued).

NYC Building Code (1968)

NYC Building Code

(2001)

NY State Building

Construction Code (1964)

Sub-A rticle 1107.0 Pile Foundations - Loads

Article 8 Pile Foundations

- Loads

1107.1 Allowable

Axial Load

The allowable axial load on a pile shall be

the least value permitted by consideration of

the following factors;

(a) The capacity of the pile as a structural member. Provisions for the embedded

portion of the pile, and the portion that is not embedded, and the load distribution along embedded portion of the pile are gi\ en.

(b) Allowable bearing pressure on soil strata underlying the pile tips: The allowable pile load shall be limited by the provision that the pressures in materials at and below the pile

tips shall not exceed the allowable beanng

values in 1 103.0. Provisions of 1 103.4 and

1 103.5 shall apply. The transfer of load from

piles to soil shall be determined by a recognized method of analysis. Alternative methods to determine load transfer are given

for piles in different soil classes. In addition, beanng strata shall be established, to which

the piles in the various sections of the building are to be penetrated.

(c) Capacity as indicated by resistance to penetration: Where soils that the piles must

penetrate consist of matenals that present a hazard to the installation of the piles, the selection of types of piles and penetration

critena shall be subjected to approval. But

in no case shall the minimum penetration

resistance be less than that stipulated in Tables 1 1-4 and 1 1-5 [Annex Bl]. Detailed provisions are given for ( 1 ) piles installed by

use of steam-powered, air-powered, diesel- powered or hydraulic impact hammers. (2) piles installed byjacking or other static forces, and (3) piles installed by use of

vibration hammer.

(d) Capacity as indicated by load test - Load

test requirements are given for piles installed by static forces, by impact hammers, and by

use of vibration hammers. Provisions for load test procedures are also given. Foundation piles within the area of mfluence

of a given satisfactory load-tested pile shall be installed under identical conditions. Group load tests up to 1 50 % of the proposed group load may be required for

pile groups. And temporary supporting

capacity the soil might provide to the pile dunng the test shall be obviated by "casing

oft^'. (e) Maximum loads.- ( 1 ) Basic maximum

load: Except as permitted m the provisions of (2) below, the maximum pile load shall not exceed the values in Table 1 1-6 [Annex

Bl]. (2) Substantiation of higher allowable

loads: load values higher than those in Table

1 1 -6 [Annex B 1 ] can be substantiated on the basis of test and analysis. Detailed

provisions are given.

27-700 Same

NISTNCSTAR 1-1 B. WTC Investigation 161
Table 7-4

Table 7-4. Foundations (continued).

Municipal Code of Chicago (1967) BOCA Building Code - Basic Code (1965) Comments

70-5 Allowable Loads on Piles 739. 0 Allowable Pile Loads

The average compressive stress on any

cross-section of a pile under design

load shall not exceed the allowable value for the material as provided in Chapters 72, 73. 74. All concrete in piling shall have a min. ultimate compressive strength of 3000 psi. 70-5.1 For pile loads not exceeding 25

tons for timber piles, nor 40 tons for concrete piles, concrete-filled steel pipe

piles and rolled structural steel piles, the allowable pile loads may be determined by the value R obtained by

one of the following formulas: Formulas for piles whose weight is equal to or less than, and whose is larger than, the weight of the striking part are given, respectively. R is the allowable pile load and is function of weight of the striking part, effective fall height, actual energy delivered by

hammer per blow, penetration of pile per blow and weight of pile. 70-5.2 For pile loads exceeding 25 tons

for timber or 40 tons for concrete etc, the allowable pile load shall be

determined by control load tests as required in Section 70-5.3. 70-5.3 (a) The number of control test piles shall be determined by engineer

or architect by the degree of variation

in soil conditions.

(b) A pile to be tested shall be loaded to double the proposed allowable load. Same as in 70-2.5 (b). (c) Measurement of settlement shall be

taken and recorded immediately before and after each increment of load. In determining the settlement, proper

deduction shall be made for elastic compression of the pile under test load.

(d) The proposed allowable load shall be considered acceptable if the total net settlement under the total test load,

after the elastic compression of the pile under the test load has been deducted, does not exceed 0.01 in. /ton of total test load.

(e) The proposed allowable load, if acceptable, shall be allowable for all piles driven in the same soil conditions

if the driving resistance is not less than

that of the control test pile. 70-5.4 (a) Where the resistance of a

pile is developed in or above a compressible soil layer, the settlement due to compression of this soil shall be considered in the design, (b) Where

the piles are jetted into position, allowable loads shall be determined

either by Section 70-5.1 or 70-5.3.

Shall be determined by applicable fonnulas. The maximum load capacity

shall be limited by the supporting capacity of the soil as determined by driving

resistance or by load test, but shall not exceed the capacity of the pile designed as

a short or long column.

739.1 Short column load. Except when

extending above pemianent ground level, or dnven in material of negligible lateral support, or driven through soil which will be later removed, all piles shall be

designed as short columns under the provisions of the basic code for the

structural matenal used. The average compressive stress in any section of the

pile shall not exceed the allowable column

values of the basic code. 739.2 Driving fomiula load. The allowable

load on any pile determined by the application of an approved driven formula

shall not be >40 tons. 739.3 Approved test load. When greater loads per pile than permitted in Section 739.2 are desired, control piles shall be

tested with the procedure in Section

727. The resulting allowable load shall be

<l/2 of the test load which produces a permanent net settlement/ton not more

than 0.01 in. All other piles shall have the capacity as that of the control pile, except

as provided in Section 739.4. Not less than

3 piles shall be driven in any area of

uniform foundation materials and ! of

such shall be test loaded. At least 1 test shall be made for each 1 5,000 sft of

building area. 739.4 Group Pile load. 1. Limiting load. The total load on group of piles shall not exceed the bearing capacity on the gross loaded area of the underlying soil stratum, assuming a unifonn load spread within 60" with the horizontal from the area occupied

by the pile group + 1 ft surrounding the periphery of the cluster. No overlapping of

pressure areas from similar distribution of

loads for adjacent pile groups. 2. Load test of pile groups: When driven through

materials subjected to displacement or

shifts, the immediate surrounding pile groups shall be driven in place before the

test load is applied to that group. 739.5 Limiting pile loads: 200 tons when

open-ended concrete-filled steel pipe piles are installed to bear on rock; 120 tons on

all other types of piles when bearing on

rock except timber piles (740.6); 80 tons when bearing on or in materials of classes

3,4,5 in Table 15.; 60 tons when bearing on or in materials classified in Table 15 [Annex B5].

162 NISTNCSTAR 1-1 B, WTC Investigation
Foundations

Table 7-4. Foundations (continued).

NYC Building Code (1968) NYC Building Code (2001)

NY State Building

Construction Code (1964)

1107.2 Allowable

Lateral Load

Provisions for allowable lateral load are given.

27-701 Same

1107.3 Uplift Capacity A mmimum safety' factor of 2 against withdrawal shall be provided. Shall be

greater than 2 if subjected to dynamic

uplifting. If factor of 3 or more is used, no need for pull-out test.

27-702 Same

Sub-Article 1108.0 Pile Driving Operations Article 9 Pile Driving Operations

The provisions of this article shall not apply to piles driven with a vibration hammer or other equipment wherein the

energy- of impact cannot be evaluated.

1108.1 Equipment General provisions for equipment and

specific provisions for cushion or cap

block and followers are given.

27-704 Same

1108.2 Procedure Pro\ isions for Continuous driving.

Jetting. Sequence of installation. Heaved piles, and Penetration measurements are given.

27-705 Same

Sub-Article 1 1 09. 0 Pile Types - Specific

Requirements

Article 10 Pile Types - Specific

Requirements

1109.1 Scope 27-706 Same

1109.2 Timber

Piles

(a) Materials: Timber piles shall conform in quality to class A or B of RS 11-7 [Annex A5]. Provisions are given for the size of the piles. The

limits for stress due to the applied loads

are given for various wood types.

(b) Limitation on use; Terminate

driving directly when the pile reaches bearing on hard materials.

(c) Legged and invened piles: Provisions for double legging and

single legging and invened piles are given.

(d) Installation: Damaged materials at the head of the pile shall be removed

before capping. Sudden decrease in dri\ ing load shall be investigated, and may be adequate cause for rejection of

the pile.

27-707 Same

1 109.3 Precast Concrete

Piles

(a) Matenals: Shall conform to C26-

1004.0.

(h) Construction: Provisions for handling stress, minimum lateral dimension are given. Structural design

shall conform to 1 107.0 and additional requirements for reinforcement, etc are given.

(c) Tolerances: Tolerances for eccentricity are given.

(d) Installation: Precast pile shall not be handled or driven until they have cured

sufficiently to develop the necessary

strength.

27-708 Same

NISTNCSTAR 1-1 B, WTC Investigation 163
Table 7-4

Table 7-4. Foundations (continued).

Municipal Code of Chicago (1967) BOCA Building Code - Basic Code (1965)

This is an important

provision that is only

in the NYC Building Code.

737.8 Jetting Piles may be jetted through foundation

material listed as Class 6-9 in Table 15 [Annex Bl]. Immediately after completion of the jetting, the piles shall be dnven to the required load

resistance.

70-6 Timber

Piles

70-6T Timber piles shall be single pieces of timber of approved species containing no defect. Provisions for shape and diameter of piles are

given. 70-6.2 All untreated timber piles

shall be cut off at a level not less than 1 ft below the pennanent

ground water level. 70-6.3 Timber piles above

permanent ground water level shall be treated to prevent decay.

740.0 Timber

Piles

1 . Species.- Approved species are given. All timber piles shall be driven

in one piece except for composite piles as provided in Section 746.

2. Timber specifications. -Specification

for round timber piles are given.

3. Min dimensions.- Shall comply with

Section 737.5 with some specified exceptions.

4. Cut-off - The tops shall be sawn off

in a horizontal plane. If untreated, shall be below water level, except for light frame construction.

5. Untreated piles.- Provisions for creosoted piles are given.

6. Maximum load on piles.- Maximum

load on Class A or B piles shall be as in Section 739.0. Piles of smaller sizes

shall be as in Sections 739.3 and 740.3.

70-7 Precast Concret

e Piles

70-7.1 Piles shall be reinforced to

resist both handling and driving

stresses. The diameter of precast pile

shall be not less than 8 in, and at the top shall be at least 2 % of the

length. Concrete cover of

reinforcing shall be not less than 1 .5

in. 70-7.2 Precast piles shall not be

handled nor driven until the min.

ultimate compressive strength of 3000 psi of the concrete has been

attained.

741.0 Precast Concret

e Piles

1 . Concrete strength.- Shall be driven

after attaining compressive strength of

not less than 3000 psi.

2. Design: Shall be in accordance with Appendix B [Annex A5]. Lateral reinforcement at both ends of the pile shall be spaced in not more than 3 in.

3. Protection: 2 in. cover shall be

provided over all reinforcement, except

for severe exposure, where 3 in. cover

shall be provided.

164 NISTNCSTAR 1-1 B, WTC Investigation
Foundations

Table 7-4. Foundations (continued).

NYC Building Code (1968) NYC Building Code (2001)

NY State Building

Construction Code (1964)

1109.4 Cast-ln- Place Concrete

Piles

(a) Descnption: Shall be cast in shells previously installed in the ground or, with the limitations in 1 1 06. 1 0. may

be cast in an uncased hole. They may

be tapered or cylindrical, or a combination of tapered and

cylindrical shapes.

(b) .Matenals: Provisions for concrete and pile shells are given.

(c) Installation: After installation to

final depth and immediately before

filling with concrete, the inside of the

tube, shell, or bore shall be

thoroughly cleaned and inspected. Concrete shall be filled so that the

entire volume is filled and separation of ingredients shall be precluded. No

concrete shall be placed in a cast-in- place pile until all piles within a radius of 1 5 ft, or within the heave

range, have been driven. Rejected

shells shall be filled with sand or

concrete. TTie concrete cap shall not be placed until at least 1 hr. after all piles within the cap group are completely filled.

27-709 Same

1109.5 Compacted

Concrete

Piles

(a) Description: A concrete pile formed with an enlarged base in which the concrete in the base is placed in small batches that are compacted prior to attaining an initial

set. (b) Materials: Provisions for concrete

properties are given.

(c) Spacing: Minimum spacing between compacted concrete piles is given.

(d) Installation: Provisions for the

installation of the base concrete and

the shaft are given.

(e) Bearing materials: Provisions for

the bearing materials for the enlarged

base are given.

27-710 Same

1109.6 Steel H

Sections

(a) Matenals: H sections shall be of any steel permined by RS 10-5 [Annex A5]. TTie use of built-up sections or sections other than H will be permined if the sections are adequately connected or the width thickness ratios do not exceed

those of H shapes.

(b) Limitations on use: Driving shall be terminated directly when the pile reaches reftjsal on the rock surface.

27-71 1 Same

NISTNCSTAR 1-1 B, WTC Investigation 165
Table 7-4

Table 7-4. Foundations (continued).

Municipal Code of Chicago (1967) BOCA Building Code - Basic Code (1965) Comments

70-8 Cast-ln- Place Concrete

Piles

70-8.1 Construction. Permanent metal

casings shall m all cases be used with

cast-in-place concrete piles. Casing shall be inspected before fill, and shall not be buckled or otherwise damaged.

70-8.2 Allowable stresses. The maximum compressive stress shall not exceed 40 % of the ultimate compressive

strength of the concrete. Where the metal

casing is 1/8 in. or more in thickness, the

pile shall be considered a concrete-filled

steel pipe pile.

742.0 Cast-ln- Place Concrete

piles

1 . Concrete strength: Shall develop a compressive strength of not less than 2500 psi at 28 days. Shall be

deposited continuously and placed in the dry.

2. Design: Reinforcement shall be

installed as an assembly. No

reinforcement (except dowel) shall be placed within 1 in. of metal

casing. Concrete cover shall be not

less than 2 in. if no permanent casing

is used, and shall be not less than 3

in. if in severe exposure.

3. Installation: Prevent distortion or

injury of piles already in use.

4. Inspection: Previous to placing of

concrete, the shell and other unfilled space of each pile shall be inspected.

70-10 Rolled

Structural

Steel Pipes

70-10.1 The steel shall conform to Chap. 74, and shall be of "H" form. The

flange projection shall not exceed 14 times the min. thickness of metal in either the flange or the web. The nominal

flange width shall be not less than 8 in. Flanges and webs shall have a min

nominal thickness of 3/8 in. 70-10.2 Splices in steel pipes shall develop the strength of the pile in compression, tension, bending and shear. 70-10.3 The max compressive stress in the steel shall not exceed 12,000 psi. 70-10.4 If the steel is exposed to the air or other corrosive agents, 1/16 in. shall be deducted from the thickness of the metal in computing the allowable load. Protective measures shall be employed if serious deterioration can occur.

745.0 Structural

Steel Pipes

1. Steel: Shall have min. nominal

thickness of 3/8 in. When of H

section, flange projection shall be not more than 14 times the minimum

thickness of metal.

2. Splices: Shall comply with Section

737.7.

3. Protection: Piles shall be protected under the conditions of Section 738.

166 NISTNCSTAR 1-1B, WTC Investigation
Foundations

Table 7-4. Foundations (continued).

NYC Building Code (1968) NYC Building Code (2001)

NY State Building

Construction Code (1964)

1109.7 ConcreteFilled Pipe

Piles

(a) Matenals: The pile shall conform

to RS 1 1-8 [Annex A5]. Concrete

shall conform to 1004.0.

(b) Minimum dimensions: Provisions

for pipes installed open-ended and

with ends closed are given.

(c) Installation: Pipe shells shall be

cleaned after driving. After driving and cleaning the pipe, open-ended

piles shall be reseated to full bearing by redriving to the resistance indicated in Table 1 1-4 [Annex Bl]

until the penetration on redrivmg is less than 2". Pipes shall be inspected before filling with concrete. Placing of concrete fill in pipe shells shall conform to the requirements for cast- in-place piles.

27-712 Same

1 109.8 Caisson

Piles

(a) Description: Caisson piles shall denote concrete filled pipe piles that are socketed into bedrocks of class 1- 65, 2-65 or 3-65 and constructed with

steel cores.

(b) Materials: Requirements for pipe,

shell, concrete and steel cores are given.

(c) Design of rock socket: Shall be

predicted on the sum of the allowable

bearing pressure on the bottom of the socket plus bond along the sides of

the socket. Provisions for the allowable bearing pressure and bond

stress are given.

(d) Spacing and minimum

dimensions: Requirements for minimum diameter, shell thickness, depth of socket for a caisson and the center-to-center spacing are given.

(e) Installation: Provisions are given

for the installation of the steel shell, the socket, the steel core, and concrete and grout. Provisions for water

leakage are also given.

27-713 Same

NISTNCSTAR 1-1B, WTC Investigation 167
Table 7-4

Table 7-4. Foundations (continued).

Municipal Code of Chicago (1967) BOCA Building Code - Basic Code (1965) Comments

70-9 Concrete- Filled Steel

Piles

70-9.1 Construction. Steel pipes shall comply

with ASTM for welded and seamless steel pipe piles (A252-55). Pipe to be driven open- ended shall have a min. nominal outside diameter of 10.75 in. Minimum nominal wall

thickness for diameters less than 14 in. shall be 0.25". For diameter of 14 in. or more, the minimum wall thickness shall be 0.375 in. Pipe to be driven close-ended shall have a

steel end of approved design. Minimum

outside diameter shall be 10.75 in. Minimum

wall thickness for diameters less than 14 in. shall be 0.125 in. For diameters of 14 in. or more, the minimum wall thickness shall be

0.2 in. If wall thicknesses are less than these

values, the piles shall be considered as cast- in-place concrete piles. 70-9.2 The maximum compressive stress in concrete shall not exceed 40 % of the ultimate

strength of the concrete. Maximum

compressive stress in the steel pipe shall not exceed 12,000 psi. 70-9.3 Durability. ]f the steel pipe is exposed

to the air or other coiTOsive agents, 1/16 in. steel shall be deducted from the thickness of

the metal in computing the allowable load. Suitable approved protective measures

against deterioration shall be employed if serious deterioration can occur.

743.0 Steel Pipe and

Tapered

Tubular

Piles

1 . Concrete strength; Concrete shall have a minimum compressive strength of 2500 psi at 28 days.

2. Steel pipe: Shall confomi to Appendix C

[Annex A5].

3. Design: Reinforcement shall be installed as an assembly or may consist of 1 or more rolled

structural shape cores. A minimum clearance of 1" shall be maintained berween the reinforcement and enclosing shell.

4. Minimum thickness: The minimum wall

thickness of all load bearing pipe, rube and

shell shall be 1/10".

5. Splices: Shall comply with Section 737.7 and insure true alignment and load

transmission.

744.0 Drilled Caissons1. Construction: Shall consist of a shaft section of concrete-filled pipe extending to bed rock

with an uncased socket drilled into the bed

rock which is filled with concrete thoroughly bonded to the rock wall.

2. Steel shell: Shall be steel pipe with a minimum yield point of 33 ksi fitted with an approved cutting shoe and structural cap. None

but the top section of the pipe shall be less than 40 ft long. The minimum diameter shall be 24

in., and the minimum shell thickness shall be

5/16 in.

3. Concrete fills: Shall be controlled concrete, with a min. compressive strength of 3500 psi at 28 days, deposited with a slump of < 6 in. 4- Rock socket: Shall be drilled in sound rock, and shall be thoroughly cleaned. The concrete

fill shall be deposited in the dry. The depth of

the socket shall be adequate to develop the full load-bearing capacity within the limitations of

Table 15 [Annex B5].

5. Reinforcing core: Structural steel core used

for reinforcement shall not exceed in area 25 %

of the gross caisson section. Minimum

clearance berween core and shell shall be 2 in. In all cases, not less than 1 in. concrete covenng shall be provided.

6. Driving precautions: No drilled caissons

shall be driven more than 2 % of the length out of plumb.

7. Spacing: The minimum center-to-center spacing between caissons when no steel core is used shall be twice the diameter of the shell; when reinforced with a core, such spacing shall be not less than 2.5 times the diameter.

168 NISTNCSTAR 1-1 B, WTC Investigation
Foundations

Table 7-4. Foundations (continued).

NYC Building Code (1968) NYC Building Code (2001)

NY State Building

Construction Code (1964)

1109.9 Composite

Piles

Composite piles include those

consisting of rwo t>'pes of pile joined

together. Provisions for the allowable

load and the joint between two

components are given.

27-714 Same

Sub-Article 1110.0 Underpinning Article 11 Underpinning

1110.1 General Requireme

nts

Where support of adjacent structures is required, such support may be pro\ ided by underpinning, sheeting, and bracing.

27-715 Same

1110.2 Use of Rock

Support in Lieu of Underpinning

Existing structures founded at a level above the level of adjacent new- construction may be supported on hard

rock in lieu of underpinning, the use of

sheeting and bracing, or the construction of retaining wails provided that the safer\' of the construction can be substantiated.

27-716 Same

Sub-Article IIII.O Stahility Article 12 Stability

1111.1 General The possibility of overturning and

sliding of the building shall be

considered.

27-717 Same

1 1 1 1.2 Factor of

Safety

(a) Ovenuming: Minimum safety

factor against overturning of the

structure shall be 1 .5. Stability against overturning shall be provided by the dead load of the building, by the allowable uplift capacity of piling, by

anchors, by the weight of soil directly overlying footings provided that such

soil cannot by excavated without

recourse to major modification of the building, or by the combination of

these factors.

(b) Sliding: Minimum safety factor against sliding shall be 1 .5. Resistance

to lateral load shall be provided by

fnction between the foundation and the underlying soil, by passive earth pressure, by batter piles, or by plumb

piles. Detailed provisions are given for

specific resistance mechanisms.

27-718 Same

NISTNCSTAR 1-1 B, WTC Investigation 169
Table 7-4

Table 7-4. Foundations (continued).

Municipal Code of Chicago (1967) BOCA Building Code - Basic Code (1965) Comments

70-11 Special Type

Piles

The use of types of piles not

specifically mentioned in Sections 70-6 to 70-10 including composite

piles, and the use of piles under

conditions not specifically covered

shall be permitted, subject to compliance with the provisions of

Chapters 72, 73, 74.

746.0 Composi

te Piles

1. Design: Composite piles consisting of 2 or more approved pile types shall be designed to meet the conditions of

installation.

2. Limitation of load; The maximum

load shall be limited by the capacity of

the weakest section.

3. Splices: Splices between concrete and steel or wood section shall be

designed to prevent separation of the

concrete portion has set, and to insure alignment and transmission of total pile

load. Splices shall be designed to resist upheaval during driving of adjacent

piles and shall develop the full compressive strength and not less than 50 % of the strength in tension and

bending of the weaker section.

747.0 Special

Piles and

Caissons

Types of piles or caissons not covered

in the Basic Code shall be pennitted provided that sufficient test data, design and construction information is filed.

170 NISTNCSTAR 1-1B, WTC Investigation
Foundations

Table 7-4. Foundations (continued).

NYC Building Code (1968) NYC Building Code (2001)

NY State Building

Construction Code (1964)

Sub-Article 1112.0 Inspection Article 13 Inspection

1112.1 General The applicable provisions of C26-

106.0 shall apply.

27-719 Same

1112.2 Bonng

Operation

Boring operations shall be subjected

to controlled inspection. Detailed

provisions are given for the inspection.

27-720 The section title changed to "Boring and Test pit operations"; In the following

text, "bonng and test pit" replaced "boring".

1112.3 Piling The installation of all piles shall be

subjected to controlled inspection. Detailed provisions are given.

27-721 Same

1112.4 Footings. Foundation

Piers, Foundation

Walls and

Pile Caps

Provisions of 1105.1 shall apply. 27-722 Same

11 12.5 Subgrade for Footings, Foundation

Piers, and

Foundation

Walls

The soil materials directly undrlying

footing, foundation piers, and

foundation walls shall be inspected by an architect or engineer after excavation and immediately prior to construction of the footings. Detailed

provisions are given.

27-723 Same

1112.6 Construction Required for or Affecting

the Support of Adjacent

Properties or Buildings

All construction or excavation

required for or affecting the support of adjacent properties or buildmgs

shall be subject to controlled

inspection.

27-724 Same

NISTNCSTAR 1-1B, WTC Investigation 171
Table 7-4

Table 7-4. Foundations (continued).

Municipal Code of Chicago (1967) BOCA Building Code - Basic Code (1965) Comments

172 NISTNCSTAR 1-1B, WTC Investigation
Annex A1

Reference Standards of 1 968 New York City Building Code

A1.1 REFERENCE STANDARDS

RS 9 Loads

RS 9-1 Minimum Unit Design Dead Loads for Structural Design Purposes. Unit design dead

loads are shown in Exhibit RS 9-1. RS 9-2 Minimum Requirements for Uniformly Distributed and Concentrated Live Loads.

Minimum uniformly distributed and concentrated live loads are shown in Exhibit

RS 9-2. RS 9-3 AASHO 1 965. Standard Specification for Highway Bridges.

RS 9-4 AREA 1 967, Specification for Steel Railway Bridges.

RS 9-5 Minimum Design Wind Pressures. Provisions for wind pressures are shown in Exhibit RS 9-5.^

RSIO Structural Work

RS 10-1 Masonry. Requirements for unreinforced masonry are given.

RS 1 0-2 USASl A-41 .2 1 960, Building Code Requirements for Reinforced Masoniy.

RS 10-3 ACI 318 1963, Building Code Requirementsfor Reinforced Concrete. RS 10-4 ACI 525 1963, Requirementsfor Thin-Section Precast Concrete Construction.

RS 1 0-5 AISC 1 963, Specificationsfor the Design, Fabrication and Erection ofStructural

Steelfor Buildings.

RS 10-6 AISI 1962, Specification for the Design ofLight Gage Cold-Formed Steel Structural

Members.

RS 1 0-8 NLMA 1 962, National Design Specification for Stress-Graded Lumber and Its Fastenings.

RS 1 0-9 Plywood Construction

RS 10-10 ASCE \962i. Suggested Specificationsfor Structures ofAluminum Alloy, 606\-l()

and 6062-T6.

RS 10-11 ASCE 1 963 , Suggested Specifications for Structures ofAluminum Alloy, 6063-T5

and 6063-T6.

RS 10-12 USASl A59. 1 1 954, American Standard Specificationsfor Reinforced Gypsum

Concrete. RS 1 0- 1 5 ACI 506 1 966, Recommended Practicefor Shotcreting.

NISTNCSTAR 1-1B. WTC Investigation 173
Annex A

RS 1 0- 1 7 ASTM-C 39 1 966, Standard Method of Test for Compressive Strength ofMolded

Concrete Cylinders.

RS 10-18 CS 253 1963, U.S. Commercial Standardfor Structural Glued-Laminated Lumber.

RS 10-21 ASTM C 192 1962, Standard Method ofMaking and Curing Concrete Compression

and Flexure Test Specimens in the Laboratoiy (tentative).

RS 10-44 ASTM-C 494 1967, Specifications for Chemical Admixtures for Concrete (tentative).

RS 10-45 Report of Committee 334, Concrete Shell Design and Construction, of the American

Concrete Institute, Adjournal, Proc. V 61, No. 9, Sept. 1964.

RS 10-65 ACI 61 3A 1 959, Recommended Practice for Selecting Proportions for Structural

Lightweight Concrete.

Foundations

^ AWPA C4 1965, Standardfor the Presei-vative Treatment ofPoles by Pressure

Processes. ASTM D 25 1958, Standard Specification for Round-Timber Poles.

ASTM A 252 1963T, Specification for Welded and Seamless Steel Pipe Poles.

RS 11 RS 11-4

RS 11-7

RS 11-8

174 NISTNCSTAR 1-1B, WTC Investigation
Reference Standards of 1968 NYC Building Code

A1.2 EXHIBITS

Exhibit RS 9-1 Minimum Design Dead Loads

REFERENCE STANDARD RS 9-1 MINIMUM UNIT DESIGN DEAD LOADS FOR STRUCTURAL

DESIGN PURPOSES

WALLS AND PARTmONS (unplajtered>— Weight (psO

Clay brickHigh absorpiion (per 4 in. wythe) 33 Low absoiption (per 4 in. wythc) > . . 45

Concrete brick

4 in 46

4 in. lightwei^ aggregate 33

8 in 89

8 in lightweight aggregate 68

12 m

" 130

1 2 in. lightweight aggregate 98

Sand-lime brick

per 4 in. wythe 38

Solid concreie block

4 in 40

4 in. lightweight aggregate 27

8 in. 67

8 in. lighiwcight aggregate 48

12 in 108

12 in. Iighiweighi aggregate 72 Hollow concrete block

4 ia 30 4 in. lightweight aggregate 20

8 in 53

8 in. lightweight aggregate 38

12 in 85

1 2 m. lightweight aggregate 55 Sohd gypsum block

(per in thickness) 6 Hollow gypsum block

2 in 9.5 4 in. !2.5 6 in 18 5 Clay tile, load bearing

4 in 24

8 in 42

12 in 58

Clay tile, non-load bearing

2 in II 4 in. 18 8 in. 34

12 in 46

Facing tile

2 in 16 6 in. 29

8 la 41

Split terra cotta furring tile

1 '/i in 8

2 in 10

3 in 12 Glass block

4 in. 20 PLASTER PARTmONS— Weight (psO

2 in. thick, solid cement plaster on metal lath 25

2 ia thick, solid gypsum plaster on mei.al lath 18 Mcial studs, any lath, and in. gypsum plaster, both sides 18 Wood studs, any lath, and V* in. gypsum plaster, both sides 19

NISTNCSTAR 1-1 B, WTC Investigation 175
Annex A1

Exhibit RS 9-1 Minimum Design Dead Loads (Continued)

EQUIVALENT UNIFORM PARXmON LOADS

Equivalent Uniform Load (psfj Partition weigh (plf) (To be added to floor dead and live loads

)

50 or less 0

51 to 100 6

101 to 200 12

201 to 350 20

Greater than 350 20 plus a concentrated live load of the weight in excess of 350 plf. PLASTER ON MASONRY SURFACES

(jypsum, with sand aggregate, per in 8.5 Gypsum, with hghixvcighi aggregate, per in 4

Gypsum, with wood fibers, per in 6.5 Cement, with sand aggregate, per in 10 Cement, with Itghiwcight aggregate, per in 5 FLOOR FINISHES (F.xcluding fill or base) -

Resilient flooring {asphalt tile, linoleum, etc.) 2 Asphalt block, 2 in 24 Wood block, 3 in 10 Hardwood flooring. % in. 4 Softwood sub-flooring, per in 3 Plywood sub-flooring, '/i in L5

Ceramic or quarry tile, I in 12 lerrazzo, 1 in , 12

Slate, 1 in 15 Cement, 1 in 12 FLOOR FILL -

Cinders, no cement, per in 5 Cinders, with cement, per in 9

Sand, per in 8

FLOORS - WOOD JOIST CONSTRUCTION

(With double layer wood flooring — no ceiling)

Total iVeisht (psf)

Joint Sizex (in.) 12 in. Joi\t Spacing 16 in. Joist Spacing

2x6 6 -5

2x8 6 6

2 X 10 7 6

2 X 12 8 7 3x6 7 6

3x8 8 7

3 X 10 9 8

3 X 12 11 9

3 X 14 12 10

CEILINGS (including suspension system) - Weight (psf)

Plaster on tile or concrete — sec "Plaster on Masonry Surfaces" Suspended metal lath and gypsum plaster, % in. . . . . . . j . . . 9 Suspended metal lath and cement plaster, % in 11 Suspended acoustical tile 2 ROOF AND WALL COVERINGS -

Clay roofing tiles • • Built-up roofing;

3-piy

5-ply

1.5 2.5 Gravel, Vi to % in ^

(Continued on next page)

176 NISTNCSTAR 1-1 B, WTC Investigation
Reference Standards of 1968 NYC Building Code

Exhibit RS 9-1 Minimum Design Dead Loads (Continued)

Slag. CO H in 3 Crushed rock. lo % in 4.5 Aluminum sheet: 0.050 in. thick, flat 0.72 0,032 in. thick, corrugated 0.55 0.032 in. thick. V-Beam 0.58

Steel, 20 gauge, protected V-Beam 2.3 Tin Sheet, 28 gauge 1 Asbcstos-ccmcnt, corrugated roofing, % in 4

Fibcrboard, '/i in 0.8 Gypsum sheathing, Vi in 2 Wood sheathing, per in 3 Wood shingles, in place 3 Asphalt shingles, in place 6

Asbestos-cement shingles, in place ' 4 Cement tile. ^ in. in place 16 Stucco (cement), per in 10

Slate, 3/16 in. in place 7

Slate, V* in. in place IG

Skylight, metal frame, % in. wire glass 10 MISCELLANEOUS MATERIALS -

Glass- Weight (psf)

single strength 1.2 double strength 1.6

plate, wired or structured, in 1.6

insulating, double Vi in. plates w/air space 3.5

insulating, double '^ in. plates w/air space 7.1 Insulation —

fiber glass, per in 1.5 foam glass, per in 0.8 Urethane, 1 in 1.0 2 in 1.2 cork, per in I.O vegetable fiber boards, per in 1.5 bats and blankets, per in 0.5

vermiculite. loose fill — 0.6 pcf

expanded polystyrene — 1.0 pcf

Marble, interior, per in 14

Plastic, acrylic, V* in 1.5

Slate, per in 15 Weight (psO

Asphaltic concrete 144

Cast-stone ma.sonry (cement, stone, sand) 144 Cinder fill 57

Concrete, plain (other than expanded aggregates) —

cinder 108

slag 132

stone (including gravel) 144

Reinforced concrete —

Add 6 pcf to unit weights shown for plain concrete Cork, compressed 14

(Continued on next page)

NISTNCSTAR 1-1B, WTC Investigation 177
Annex A1

Exhibit RS 9-1 Minimum Design Dead Loads (Continued)

Earth , 100 Masonry, ashlar —

granite , 165

limestone (crystalline) 165

limestone {oolitic) 135 marble 173

sandstone (bluestone) 144

Ma.sonry, rubble w/mortar —

granite 153

limestone (cr>'staUir»e) 147

limestone (oolitic) 138 marble 1 56

sandstone (bluestone) 137

Ma.sonry, dry rubble —

granite 130

limestone (oolitic) 125 marble 130

sandstone (bluestone) 110 Terra colta, architectural —

voids filled ! 20

voids empty , 72

Timber, seasoned -

pine, Douglas fir. and simitar species 35

oak. elm, and similar species 45

Exhibit RS 9-2 IVIinimum Live Loads

REFERENCE STANDARD RS 9-2 MINIMUM REQUIREMENTS FOR UNIFORMLY DISTRIBUTED AND

CONCENTRATED LIVE IjOADS

UNIFORMLY DISTRIBUTED LIVE LOADS

Occupancy or Use of Spaces Live load (psf)

Assembly spaces

Drill rooms 1 50

Assembly spaces having fixed seats, including auditorium areas

in churches, schools, theaters, courthouses, lodges, lecture

halls, and similar buildings 60*

Dance floors, restaurant serving and dining areas, mess halls,

^ museums, gymnasiums, skating rinks, promenades, and roof gardens 100

Private assembly spaces, including conference rooms and

card rooms 50

Stadium, grandstand, and reviewing stand seating areas .... 100 Other assembly spaces See note ^

(Continued on next page)

178 NISTNCSTAR 1-1 B, WTC Investigation
Reference Standards of 1968 NYC Building Code

Exhibit RS 9-2 Minimum Live Loads (Continued)

Balconies

Exterior Sec note •> Interior (as required for occupancy or use)

Mezzanines (as required for occupany or use)

Catwalks 30

Corridors

(1) Corridors in schools tOO

(2) Corridors, elevators, and stairs in office buildings (other than first floor lobbies) 75

(3) Corridors serving first floor elevator lobbies, auditoriums,

and similar areas of public assembly 100

(4) Other (same as that required for the occupancy of the area being served)

Elevator machine rooms (see Reference Standard RS-18)

Equipment rooms, including pump rooms, generator rooms, trans- former vaults, and areas for switch gear, ventilating, air conditioning, and similar electrical and mechanical equipment 75

Fire escapes

Multiple dwellings 40

Others 100

Hospitals

Operating rooms, laboratories, and service areas 60

Rooms and wards 40

Personnel areas 40

Other (as required for occupany or use of the area)

Libraries Reading and study room areas 60

Stack areas (see Storage)

Other (as required for occupancy or use of the area)

Lobbies and similar areas 100

Manufacturing and repair areas 100 Marquees 60

Office areas (not including record storage areas) 50

Parking areas For passenger cars, provided that the clear headroom at the entrance does not exceed 8 ft 50

Penal institutions Cell blocks 40

Other (as required for occupancy or use of the area)

Plaza areas (open) accessible to the public (including landscaped

portions) 100

Recreation areas Bowling alleys (alleys only) 40

Poolrooms 75 Other (see assembly areas)

(Continued on next page)

NISTNCSTAR 1-1B, WTC Investigation 179
Annex A1

Exhibit RS 9-2 Minimum Live Loads (Continued)

RcMiicniial areas

Dorniilorics Non-parlitioncd , 60

Parlitioned 40

Dwellings

Miilii-lamily iinils Ap;irlincn!s 40

Public rooms (as required for occupancy or use)

One- and Iwo-family units

Firs! floor 40

Upper lloors and habitable attics 30

Uninhabitable attics 20^ Hofcls Guest rooms 40

Public rooms (as required for occupancy or use) Schools Classrooms 40

Shops (automotive and press shops) 100

Shops (others) 60

Other (as required for occupancy or use of the area)

Siairs and exit passages (same as Fire escapes)

Storage

Light 100

Warehouse 1 50

StoresWholesale sales 100

Retail sales Basement and first floor 100

Upper floors 75

Telephone equipment rooms 80

Theaters

Dressing rooms 40

Projection room 100

Stage floor 1 50

Toilet areas 40

•Notes:

a Uniform load shall be applied to the gross floor area.

l> 150 per cent of live toad on adjoining occupied area, but not more tha5> !00 psf.

< Live load need be applied to joists or to bottom ctiords of trusses or trussed rafters only in those portions of attic space having a clear height of 42 in. or more between joist and rafter

in conventional rafter construction; and t>etwcen bottoin chord and any other member in trussed or trussed rafter construction. However, joists or the bottom chords of trusses or

trussed rafters shall be designed to sustain the imposed dead load or 10 psf, whichever is greater, uniformly distributed over the entire span.

<3 Live loads for assembly spaces other than those described in this reference standard shall be determined from the occupant load requirements as established by section 27 .Ism usmg the formula lOO/net floor area per occupant but shall not be less than 50 psf nor more

than 100 psf.

(Continued on next page)

180 NISTNCSTAR 1-1B, WTC Investigation
Reference Standards of 1968 NYC Building Code

Exhibit RS 9-2 Minimum Live Loads (Continued)

CON't KMRAIKl) IJVK l.t)AI)S

Usi' or l.ncaiioii l.oati (tl>s.)'> licmuiks

Elevator machine room

floor Gratings, checkered

plates and similar nKial decks

Floor registers and similar floor insets Parking areas — passen- ger vehicles accommodating nine passengers, or less

Parking areas — trucks, buses and passenger

vehicles accommodating more than nine pas- sengers Floor of office areas

Resident and multiple

dwellings

Scuttles and skylight ribs

Steel joists — for each in- dividual joist

Roofs

Set Rclcrcncc Sl.inil.iiil RS-iS

200 (on area ol I <• sq Nonconcurrcnl uiih iini m.) lorni live load

250 (on area of 2 li. x 2 ft.) 2.500 (on area of 20 sq

in.) For slab or dock design

1.500 (each wheel)

150 per cent of maximum wheel load with

vehicle loaded (on

area of 20 sq. in.

)

2,000

200 (on area of 4.0 sq.

in ) 200

800 (for (russed joists apply at a panel

point

)

250 (on area of 2 ft. x 2 ft.)

Nonconcurrcnl wiih uni- form live ioail. The concentrated load may be assumed to represent llic reaction

of a jack placeil uniler one end of the vehicle. Omit uniform live load

in area (6 ft. x 9 ft.) representing one half the vehicle, adjacent to the point of load concentration. To be used in lieu of uniform live load in stalls of mechanized

garages where there is no slab or deck. Same as for Parking areas — passenger vehicles accommodating nine

passengers, or less.

Nonconcurrcnl with uni- form live load. Nonconcurrent with uni- form live load. Nonconcurrent with uni- form live load. Nonconcurrent with uni- form live load.

Nonconcurrent with uni- form live loa'd. Nh)I applicable for awnings,

canopies, and similar constructions where ac- cess by persons is difficult and not intended.

(Continued on next page)

NISTNCSTAR 1-1 B, WTC Investigation 181
Annex A1

Exhibit RS 9-2 Minimum Live Loads (Continued)

Stair and fire escape

treads

Boiier rooms

300 (on area i fl. wide

by depth of Ihc tread and spaced at 3 fl.

_ center-to-center)

3,000

Nonconcurrcnt with uni- form live load.

The concentrated load of 3.000 lbs. may be as- sumed to represent the weight of minor items

of equipment (pumps,

etc.) in temporary lo- cations during installa- tion. In addition provi- sion shall be made for supf>orting the weight

of the empty boiler at pertinent locations on

the floor to provide for replacement of the

boiler.

Note:

' Except when otherwise isdicated loads are assumed to be applied over an area 2VS ft. x 2 ft.

182 NISTNCSTAR 1-1 B, WTC Investigation
Reference Standards of 1968 NYC Building Code

Exhibit RS 9-5 Minimum Design Wind Pressures

REFERENCE STANDARD RS 9-5 MINIMUM DESIGN WIND PRESSURES

1. DESIGN WIND PRESSURES ON STRUCTURAL FRAMES. - Minimum design pressures due to wind acting on venicaJ surfaces shall be in ac- cordance with table RS 9-5.1, and minimum design pressures acting normal to horizontal or inclined surfaces shall be in accooiance with table RS 9-5 2 The

occurrence of the pressures on vertical, horizontal, and inclined surfaces of the building shall be considered as simultaneous. TABLE RS 9-5.1 DESIGN WIND PRESSURF5 ON VERTICAL SURFACES

Design Wind Pressure on

Heififii Zone Vertical Surfaces (psf of

(It. above curb level) projected solid surface)

Structural Panels Frame Glass

(V-50 (signs and> similar constructions of shallow depth only.) , 15 0-100 20 30

101-300 25 30

301-600 30 35

601-1000 35 40

Over 1000 40 40

TABLE RS 9-5.2 DESIGN WIND PRESSURES ON HORIZONTAL

AND INCLINED SURFACES

Roof Slope Design Wind Pressure Normal to Surface

30 degrees or less Either pressure or suction equal to 40 per cent

of the values in Table RS 9-5.1 over the entire roof area More than 30 degrees Windward slope — pressure equal to 60 per cent

of values in Table RS 9-5.1. Leeward slope — suction equal to 40 per cent of

values in Table RS 9-5.1.

NISTNCSTAR 1-1 B, WTC Investigation

(Continued on next page)

183
Annex A

Exhibit RS 9-5 Minimum Design Wind Pressures (Continued)

2. WALL ELEMENTS. — For design of mullions, muntins, girts, panels,

and other wall elements (including their fastenings), other than glass panels, the wind pressure acting normal to wall surfaces shall be 30 psf or a 20 psf suction,

for all height zones up to 500 ft. These values shall be deemed to include allow- ance for gust pressures. For height zones over 500 ft., the applicable design pres- sures shall be specially investigated, but shall not be less than the values indicated m table RS 9-5.1.

3. ROOF ELEMENTS. ~ The wind pressures acting on purlins, roofing,

and other roof elements (including their fastenings) supporting small contributory areas of wind presentment shall be I Vz times the values given in table RS 9-5.2.

4. OTHER BUILDING ELEMENTS. - Minimum wind pressures to be

used in the design of other building elements shall be the values in table RS 9-5.1 multiplied by the following shape factors given in table RS 9-5.3. TABLE RS 9-5J SHAPE FACTORS

Construction Shape Factor

Signs (and their supports), or portions thereof, having 70 per cent

or more of solid surface ~ . . 1-5 Signs (and their supports), or portions thereof, having less than 70 per

cent of solid surface 2,0 Tanks, cooling towers, and similar constructions , . . L5

Upright, circular cylindrical surfaces , 0,7 Square and rectangular chimrteys . . 1.5

For special structures such as curved and saw-tooihed roofs, guys and cables, open

trussed structures, parallel solid girders, and spheres, the design wind pressure shall be

determined on the basis of recognized engineering analysis or by test. 5. EAVES AND CORNICES — Eaves, cornices, and overhanging elements of the building shall be designed for upward pressures of twice the values given in table RS 9-5. i. 6. WIND LOAD BY MODELTEST — In lieu of the design wind pressures established

in sections 1 and 2 of this reference standard, and subject to review and approval of the commissioner, design wind pressures may be approximated from suitably conducted model

tests. Tht. tests shall be predicated on a basic wind velocity of 80 mph at the 30 ft level, and

shall simulate and include all factors involved in considerations of wind pressure, including

pressure and suction effects, shape factors, functional effects, gusts, and internal pressures and suctions.

184 NISTNCSTAR 1-1B, WTC Investigation
Annex A2

Reference Standards of 2001 New York City Building Code

A2.1 reference standards

RS 4-5 Floodproofwg Non-Residential Structures and Coastal Construction Manual

FEMA 55/February 1986 - Design and Construction Manualfor Residential

Buildings in Coastal/High Hazard Areas

FEMA 85/ September 1985 - Manufactured home installation in flood hazard areas FEMA 102/May 1986 - Floodproofwg non-residential structures

Loads

Same as in 1968 New York City Building Code, which is given in Annex Al.

Same as in 1968 New York City Building Code, which is given in Annex Al.

AASHTO 1983. Standard Specification for Highway Bridges, 13th Edition and 1984,

1985, 1986 Interim Specifications.

AREA 1987, Specification for Steel Railway Bridges, Chapter 15, Steel Structures,

Manual for Railway Engineering.

Same as in 1968 New York City Building Code, which is given in Annex Al.

Earthquake Loads. ICBO 1988 with 1990 Accumulative Supplement, Uniform

Building Code, Section 2312, amended as in Exhibit RS 9-6 of Annex A2.

RS9

RS 9-1 RS 9-2

RS 9-3

RS 9-4

RS 9-5

RS 9-6

RS-10 Structural Work

RS 10-1 A Masonry. Requirements for Unreinforced masonry are given.

RS 1 0- 1 B Masonry - ACI 530 1 992/ASCE 5-92, Building Code Requirements for Masoniy

Structures, as modified. (Modifications are provided in the reference standard.)

ACI 530. 1.-92/ASCE 6-92, Specificationsfor Masoniy Structures, as modified.

RS 10-2 Reinforced Masonry - ACI 530-92/ASCE 5-92, Building Code Requirements for

Masoniy Structures, as modified. (Modifications are provided in the reference

standard.)

- ACI 530. 1 -92/ASCE 6-92, Specificationsfor Masoniy Structures, as modified.

RS 1 0-3 Reinforced Concrete. ACI 318 1 983, Building Code Requirements for Reinforced

Concrete. RS 1 0-3 ACI 318 1 989, Building Code Requirements for Reinforced Concrete. RS 10-4 ACI 318, 1963 and apphcable sections of ACI 318-83.

NISTNCSTAR 1-1B, WTC Investigation 185
Annex A2

RS 10-4 Precast Concrete and Prestressed Concrete - ACl 318 1989; MNL- 120- 1985.

RS 10-5A AlSC-1989, Specifications for Structural Steel Buildings - ASD and Plastic Design.

RS 10-5B AISC-LRFD 1993, Load and Resistance Factor Design Specifications for Structural

Steel Buildings.

RS 10-5C UBC Section 2723, 1990, Uniform Building Code.

RS 10-6 AISI 1986, Specifications for the Design of Cold-Formed Steel Structural Members.

RS 10-8 AF&PA 1991 and its 1991 Supplement with 1993 Revisions.

RS 10-9 Plywood Construction

RS 10-10 AA SAS 30-1986, Specifications for Aluminum Structures. RS 10-11 ASTM B 209- 1 988, Standard Specification for Aluminum andAluminum-Alloy Sheet

and Plate. \ ASTM B 308-1988

ASTM B 429-1988

RS 10-12 AF&PA Span Tables for Joists and Rafters 1993 and its Supplement

RS 1 0- 1 5 Same as in 1 968 New York City Building Code. _ RS 1 0- 1 7 ANSl/ASTM C 39- 1 984

RS 10-18 ANSl/AITC A190.1-1992; AITC 1 17-1987; AITC 1 17-1988

RS 10-21 ANSI/ASTM C 192-1981

RS 10-44 ANSI/ASTM C 494-1986

RS 10-45 ACI-ASCE-334

RS 10-65 ACI 211.2-1981

RS-11 Foundations

RSll-4 AWPAC4-1988

RS 1 1-7 ANSI/ASTM D 25; ASTM-D2899-1986

186 NISTNCSTAR 1-1B, WTC Investigation
Reference Standards of 2001 NYC Building Code

A2.2 EXHIBITS

Exhibit RS 9-6 Earthquake Loads

REFERENCE STANDARD RS 9-6 EARTHQUAKE LOADS

UBCSECnON 2312-1990

Eanhquake Regulations wiih Accumulative Supplemcn!

MODinCATlONS—The provisions of UBC Section 23 1 2 shall be subject to the following

modifications. The subdivisions, paragraphs, subpara^phs and items are from this section. Subdivision (a) General. Paragraph 1. Minimum seismic design. Delete this paragraph and substitute the following: 'The following types of construction shall, at a minimum, be designed and constructed

to resist the effects of seismic ground motions as provided m this section: new structures on new fourxlations; new structures on existing foundations, and

enlargements in and of themselves on new foundations. Buildings classified in New York

City occupancy group J-3 and not more than three stories in height need not conform to the povisions of this section. The Commissioner may require that the following types of construction be designed and

constructed to incorporate safety measures as necessary to provide safety against the effects of seismic ground motions at least equivalent to that provided in a structure to which the provisions of this section are applicable: new buildings classified in occupancy group J-3 and which are three stories or less m

height, and

enlargements in and of themselves where the costs of such enlargement exceeds sixty percent of the value of the building. Pursuant to seaion 27- 1 9 1 of the code the Commissioner shall have the authority to reject an ap>plication for a building permit which fails to comply with the requirements of this section

' Subdivision (b) Definitions. Delete the definitions ofthe following terms and substitute the following new definitions:

(Continued on next page)

NISTNCSTAR 1-1B, WTC Investigation 187
Annex A2

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188 NISTNCSTAR 1-1B, WTC Investigation
Reference Standards of 2001 NYC Building Code

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NIST NCSTAR 1-1B, WTC Investigation 189
Annex A2

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Reference Standards of 2001 NYC Building Code

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NISTNCSTAR 1-1B, WTC Investigation 191
Annex A2

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192 NISTNCSTAR 1'-1B, WTC Investigation
Annex A3

Reference Standards of 1 964 New York State Building

Construction Code

A3.1 introduction

The Generally Accepted Standards Applicable to Structural Requirements, given in A3. 2, was published

by the New York State Building Code Council for the State Building Construction Code dated January 2, 1968. This is the oldest copy the Department of State Codes Division (NY) has available at this time

(November 2003).

A3.2 generally ACCEPTED STANDARDS

Generally Accepted Stt^aarda

8pplic«.tle to Structural Pequiraaeats

ATHSSIVES n, AitBBlve, CasBln-Type, Water-ejid Hoie-Sealstact, l.M4-A-125t, 196IJ FB, Adhesive, Ursa-Fesln-Type (Llquifl *nd Povder), H«M-A-l£5t, X96O

Jdl, Adbecivc, Ffler.ol and Resorcinol Fesln Bate (Jcr Marine Service U«e) MIL-A -22397, 1560 vith i961» maenamer.t

AI'j:i3lH

AA, Alunlnure Constrjctlon K&nual, StctioR A, Speciflcetioss for Structw«s

of Aletisvaa Alloys, 1^3

ACT, rulldlag Cod* Pacuir sner.ts for Peinforced Concrete, ACT 316-63 ACT, HiniruiE StAndard P.squirtnents for Pretest Concrete Flocr »ni Boof

Units, ACT 711-5S ASU4 Various Specificetions as listed ir. Sectior. UlO of Suiidir.g Cccs

Fe<;uir».ie.--.s for Ssiiifcrcsd Concrete, ACI 3X6-62

roacA.rio.'is ase fzles

U5AS, Building Code ?.equlrer;ent j fsr Excavations sad Foundetions,

A52.1-lS5e, e.tcludins Section 5-1. 3(f); note 5 ASCI, Pile rouEdatior.s and Pile Snruttures, f-lanual of L.TSir.eering

Practice, Fo. 2'', 19i*6 !Jr?A, Cocstruc^ion ard Protection of piers and Wnarvea, No. 57, I963 AISI, ?lle rour.dtticns, 19^3, secticr.5 3.u.2(a.). 5.1, and 5-2 c>nly

•JSA3, Eulldics Cede ?e?uir«reat» for vasonry, a1.1.1-1*=3

USAS, Specifications for Cypewn Flastsxir.g, A^2.1-156U

VSAS, E^iecificttions for Portland Crswt Stucco, Alt2.2-is46 USAS, Specif icaticns for Interior lething end Furring, Ai-S.i--!??;

ITEAS.. Specification* for Peicforced GypsuT. Concr«te, A^o.l-i'JSi- VSA3, Specifici-ions for the Apnlicttioft and Finiaaitig of -JBllbcard, A97.1-1S:65 ASTM, Specifications for (iuicHldtie for Structural Purpcses, C 5-59

(Continued on next page)

NISTNCSTAR 1-1B, WTC Investigation 193
Annex A3

A3.2 Generally Accepted Standards (Continued)

ASIM, 5p«cific6tions for Katuxal Cement, C 10-6U

ASIM, Sp«cificatlons fcr Gypsum, C £2-50

ASIM, Specifications for Ceccret* Aggregates, C 33-6?

ASTM, Sp»cific»tions for Structural Clay Load-Beering Wall Tile, C 3^-62

ASIM, Specification* for Gypsum Wallboarfl, C 36-67

ASIM, Specifications for Gypeua Partitlcii Tilt or Block, C 52-5^

ASTM, Sgecifications for Caccrete Bttilflicg 3rick, C 55-6£t

ASTM, Specificaticas for Strijctural Clay Kon-Lc&d-Beaxing Tile C 56-62 ASTM, Specifieatlcas for 2'Jdiaing Erick (Solid Masonry Units fxcni Clay or Sbale), C 62-66

ASTX, Spscificatien» fcr Calcivi Silicate Faeabrtck, C 73-67

ASIM, Specifications for Hollow Load-Eearir.g Concrete Masonry Units,

C 50-66T

ASTM, Gpecifications for Masonry Caoeat, C 91-67

ASTM, Epeciflcaticna fcr Beady-Mixed Coacretti, C 5'*-67 ASTMj Specifications fcr Kollov Uon-Load-BsariBa Concrite Kasocry

Units, C 129-6j<T ASTM, Specifications for Hydraulic Hyarat«d Lime for Stract'oral Purposes, C l*il-67 ASTM, Specifications fcr Aggregatt for Masonry Hortar, C ASIM, Specifications for Sclid Loafi-Eearing Ccncrete Masonry Unit*,

C l!45-66T ASIM, Specifications for Pcrtland Cer.ent, C 150-6?

ASTM, Specifications for Air -Entraining Portland Csner.t, C 175-67

ASTM, Specifications for Hydrated Liae for Mascnrj'- Purposes, C 207~U9

ASTM, Specificatlcns for Mortar for Unit Masonry, C Z70-6kl

AST>5, SpecificatLcns fcr Lightweight Aggregates for Structural Concrete,

C 530-Sl»T

SHERTHIFG

ASTM, Specification for Gypsum Sheathing 3oard, C ?9-6?

FS, Insulation Beard, Thensal and Ins'xlation Elrck, T^jerrtal

LLL-I-?55 (1), 1562

USAS, Euilding Code Eequirements for Signs and Outdoor Display

Structures, A6O.l-lc.l9

STEEL AJTO IBOf?

Fonaed Steel

AISl, Specifications for tht r-ssign of light Cage Ccld-r creed Steel

Structural :-'erriters, 1S62

RBirforeetser.t for Concrete

Reinforcement (AST*/ SpecificAtions) as listed in B-^ilding Cede Se<5Uiresents

fcr Heinforced Concrete, ACI 31S-63, Sections K5 and UlO

(Continued on next page)

194 NISTNCSTAR 1-1B, WTC Investigation
Reference Standards of 1964 NY State Building Construction Code

A3.2 Generally Accepted Standards (Continued)

Structcral St<el and Irea

AISC, £pecifice.tion for th» Design, Fabrication and Erection of

S-tzTictura.1 Steel for Buildings, &<Scpted April, I963

AISC, SpeclficaticjKS for Structural JoinUe oair.g ASTK-A325 or A U90 Eoltc,

Approves by the Heseej-cii Coxaccil on Rlvtt«d and Bolted Structural

JointB of the Zngineeriag Poundatloc, Septto'ber, I966

ASIK, specification for Gray Iroc Castings, A Ij6-6U ASTM; Specifi;«.tlon for Welded ard SeamlesB Steel Pipe, A 53-67

AS^:, Specifications for Welded Wrous^>^-Iron Pipe, A 72-66

ASTV., Specifications for Welded anS Seaalesa Steel Pipe Piles, A £52-621

SJZ, stanSara Specifications and load Tables-Open v^'eb Steel Joists, 1567

WCCD

ASA, Fli'v-ccd aesiga Specifications, Fov. 1966

A=Ti-i, Methods for tstsbllshing Structural C-rafles cf Lirtbex, !) 2k^-€kl

A57H, Hethodf of Conducting Strength Tests of Panels for Euildi.-ig

construction, 2 72-61

CS, Vteoc Shingles: ?.ed Ceiar, Tidewater Bed Cypres*, Califcrrda

?.edwc=d, CS 31-52

CS, Hardwood Plywood, CS 35-61

CS, Structirral Clued Lar.inatad Tlxber, CS 253-63 KTrAssn. Hatior.EJ. Design Specification for Stress-Grace L'JBsber and lz$

"estenings, 196s

357AasQ. v?crkin€ Stresses for Stress-Grade LuEber, Supplensnt Mo, 1, I967,

-,c ".;ood Structural Design Data, Vol. 1, 1=57

VTTA.eez. ?lank-end-3ear. "riming for Eeaidential Eullclngs, Wood Conetructicc

Data "c. li, l;6l

WPAssn. rcavj' Ti-tex Construction Eetails, Wood Construction ISata

Imc. 5, 1961

PS, U.S. Product Standard PS-1-66 for Softwood Plywood

Vo:.d Tre.'ttnent

I"A, Sutterracear, Terrdtes, Their Prevention and Control in Buildings,

K— s a-d C-arden Eulletln Tfo. 6h, January 196O

?S, rvi.':;er, Faint, 2;<tcrior [Undercoat for Wood, Reedy-I^i:<«d, V.l-.ite ar:d Tints), IT-F-S^c, I965

?S, "'ocd preservative; Treating Practices, TT-W-571g'(l}, I962

(A'.rpA spiciflcatlcr.s and instructlens are referenced)

NISTNCSTAR 1-1 B. WTC Investigation 195
Annex A3

This page intentionally left blank.

196 NISTNCSTAR 1-1B, WTC Investigation
Annex A4

Reference Standards of 1967 Chicago Municipal Code

A4.1 reference standards

Standards that represent Accepted Engineering Practice in the Chicago Municipal Code are listed in the following table.

(a) Foundations. Piles—Timber ASTM D25-55

Piles—Welded and Seamless.

Steel Pipe ASTM A25J-S5

Piles—Wood Preservative. Treatment Douglas Fir AWPA-Cl-1958

Southern Pine AWPA-C3-1958

Creosoted Treatment AWPA-C12-1OT1

(b) Masonry. American Standard Building Code. Reqxurcmenis for MasonryMiscellaneous Publication 211 USDC-NBS-July X5. 1954

(c) Wood.

National Design Specifications for StressGrade lAunber and Its Fastenings NLMA-1957

Glu«s—For Laminated and Built-up Members FSMMM A-18S Plywood—Douglas Fir NBS-CS45.55 Plywood—Hardwood NBS-CS-35-58 Plywood—Western Softwood NBS-CS122-58

(d) Eelnforced Concrete. Building Regulations for RelnTorced Concrete AC1-31&63

(e) Reinforced Gypstun. Reinforced Gypsum Concrete ASA-A59. 1-1954

(f) Steel and Metals. Specification for the Design, Fabrication and Erection of Structural StM?l for Buildings. AISC-1963

Light Gage Cold-Formed Steel Design Manual. AISI1962

Conunentary on the 1962 edition of Light Gage Cold-Formed

Steel Design Manual. AISI1962

Pile Foundations. AISI-1963 Open Web Steel Joists—Standard Specifications and Load Tables

A.l.A File No. 13G. SJM963

(g) Plastering. Including American Standard SpeciScations for Gypsura Plastering and Interior Lathing and Furring— A42.1-1955 and A42.4-1955 Standard Specifications for Portland Cement Stucco and PorUand Cement Plastering ASA-A 42.2-1946 ASA-A42.3-1946

(h) Single Family Dwellings.

Minimum Property Requirements for Properties of One or Two

Family Living Units Located in the State of Illinois. Sections

402, 403, 406, 408 and 410 to 414 inclusive, except 'Note' to, and FHA-1947

paragraph 3 of, section 406-G shall not apply. See section 6S-5{b) which excepts FHA requirement 406-E.-4a.

(Continued on next page)

NISTNCSTAR 1-1B, WTC Investigation 197
(i) Abbreviations. ACI American Concrete Institute. AISC American Institute of Steel Construction. AISI American Iron and Steel Institute. ASA American Standards Association. ASTM American Society ior Testing Materials. AWPA American Wood Preservers Association. FHA Federal Housing Administration. FS Federal Specifications. GA Gypsum Association. NBS National Bureau of Standards, Department of Commerce. NLMA National Lumber Manufacturers Association. SJI Steel Joist Institute. USDC United States Department of Commerce.

[Amend. Coun J. I-20-50. p. 5758; 10-8-52. p. 3243; 1-26-S3, p. 4184; 5-28.58. p. 7799; U-7 58. p. 8380; 11-18-59. p. 1167; 11-15-63, p. 1244„1245.)

NISTNCSTAR 1-1B, WTC Investigation
Annex A5

Reference Standards of 1965 BOCA Building Code

A5.1 reference standards

Appendix A Accredited Authoritative Agencies.

Appendix B Accepted Engineering Practice Standards. The accepted engineering practice

standards relevant to Structural provisions are given in Exhibit B of Annex

A5.

Appendix C Material Standards. Relevant standards are given in Exhibit C of Annex A5.

Appendix D Structural Unit Test Standards. Relevant standards are given in Exhibit D of

Annex A5.

Appendix E Structural Assembly Test Standards. Relevant standards are given in Exhibit

E of Annex A5.

Appendix F Durability Test Standards. Relevant standards are given in Exhibit F of

Annex A5.

Appendix G - 1 Fire related. Appendix J Unit Design Dead Loads for Staictural Design Purposes. Minimum Design

Dead loads are given in Exhibit J of Annex A5.

Appendix K Unit Working Stresses for Ordinary Materials. Given in Exhibit K of Annex

A5.

Appendix K-1 1 Earthquake Load Design. Detailed requirements are given in Exhibit K-1 1 of

Annex A5.

Appendix K-1 2 Glass Design Criteria.

A5.2 EXHIBITS

NISTNCSTAR 1-1B, WTC Investigation 199
Annex A5

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Reference Standards of 1965 BOCA Building Code

Exhibit C IVIaterial Standards

APPENDIX C

MATERIAL STANDARDS

See also afpentiiz D lor nanddrds for tests of specific materials. CONCRETE

^KB'^ccates. Concrete Specifications for „ ASTM C 33—64

A>;grr>r.i!ts. LiKiilwcighi. fnr Strucliir.il Concreie

Specifications for _ ASTM C 330—64T

AKgrctr.iics, Lightweight, for Concrete Masonry Units

Specifications for „ XSTM C 331—64T

Aggrenaies, Liglitwcight, for Insulating Concrete

Specifications fot ASTM C 332—61 Bar Supports, Wire, m Reinforced Concrete Construction

Sin'.i>iifte<l Practice Rtcotnmciulation for _ USDC SP 4687

Floor ami Roof Units, Prcc.ist Concrete

Minimum Stanilaril Rcntiirements for ACI 711 —38 Forms for Concrete Joist Constriiciion Floors _.,USDC R 87—32 Forms for Two- Way Concrete Joist I'-loor .mil R<K>f Con$»niction....USnC R 265—63 Gypsum Concrete—Specifications for ASTM C 317—64

Masonry Units—Concrete (See MAS0NRY1

iN'.iiiiral Cement —Specifications (or _ ASTM C 10—64 Ponlanil Cement. Air- (\ntraining—Spccificutions for ASTM C !75 —64

Portlanil (Tement —Specific^itions for .ASTM C 150—64 Rcaclv-Mixeil Concrete— S|>ecificatioiis for _ ASTM C —64

Rciniorcintf (See METALS)

Roofs and Slal)s-Oi«-Crade. Verimciililc Concrete

Specifications (or ASA A 122,1 —1965 Waterproof Paper for Curing Concrete —Specifications (or .'VSTM C 17! —63

FIRE PROTECTION

rirc Rctar.iant Projicrtics of Treated Textile F.ibrics

Specific.iiii>ns (or ASTM D 626—55T INTERIOR FINISHES

Adhesive—Water Resistant Organic, for liistallatinn of Clay Tile , USDC CS 181—52

Aggregates, Inorganic, for nsc in (jypMun Plaster

Specifications for ^ A.STM C 35—62 Gypsum and fiyp'stini Products, Chemical .Analysis of

Siaiidar.l .Methods (or ...A.STM C 471—61 Gypsum Uoard Products ami (iypsiiin Partition Tile or niock. Physical Testing of—Stan.hird Mcllio.ls (or ASTM C 473—62 Gypsum [.aili —Specifications (or _ A.ST.Nf C 37—54 Gypsum f^lasters—Specifications for ASTM C 28—63

(iypsum Plasters an<l Gypsum Concrete. Pliy.sical Testing of

Standard Methods (or ASTM C 472—64

Gyi>siiin Wall hoard—Si>ecificalions (or ASTM C 36-«4

Lime. Hydrated. Normal [•"inishmu —Specifications (or A.STNf C 6—49

Li.mc. Hydrated, S|>ecial !'iiusliiiii: —.Specifications for ASTM C 206—49 Quicklime amt f-Iyiirated Lime—Mcilimls o( Physical

Testing .,f :. ASTM C 110-58

Quicklime for Stnictural Purposes—Siwcifications for .-VSTM C 3—59

(Continued on next page)

NISTNCSTAR 1-1B, WTC Investigation 201
Annex A5

Exhibit C IVIateria! Standards (Continued)

MASONRY

AKKregate. Ftn«—Method of Test for Measuring

Mortar- Making Properties of ASTM C 8"—63T

AKKrcK.ite for Nfasoiiry (jroii! —Specification for ASTM C 404—6,

Aj?grej;.-.!e tor Masonry Mortar—Specificatior»s for ASTM C !4-t—62T

Brick. lUiiiiSisiR (Soliil Masonry Uisits Made from Ciay

or Sliaie) —Spccificalions for ASTM C 62—62

Brick, Concrete n»lldinc:—Specifications for ASTM C 53

chT

Brick, F'.icing (Soli<! Masonry Units Made from Ciay

or Sliaie) —Specification for _ ASTM C 216—64

Brick. Sain!- Lime Building—Specifications for ASTM C 73—51 Cement. Masonry—Specifications for ,\STM C 91 —64 Clay F.icii!K Tile, StnicEural—Specification for ASTM C 212—60 Clay Floor Tile. Strucliiral-—Specification for ASTM C 57—57 Clay LoaiMJearinR Wall Tile, Structural—Specification for ASTM C 34—62 Clay Kon- Load-Bearing Screen Tile. .Structural

Specification for ASTNf C 530—63T

Clay Non-Load-Bearin^j Wall Tile. Structural

Specification for , _ ASTM C 56—62 Concrete Ma.sonry Units, Hollow Load Bearing

Specifications for ASTM C 64T

Concrete Masoiirv Units, Hollow Xon-Load Bearing

Specifications for ASTM C 129—64T

Concrete Masonry Units. Solid Load BcarinR

Specifications for , ASTM C 145—64T

Dry-set Portland Cement Mortar „ _„ ASA A 118.1—1959

Glazed Units'—Ceramic Glazed Structural Clay Facing Tile, Facing Brick, and Soli<t Masonry Units—Specifications for ASTM C 126—62

Gypstsm Partition Tile and Block—Specifications for ASTM C 52—54 Lime, Hydrated, for M.isonry Purposes—Specifications for ,\STM C 207—19 Limes _ (See INTERIOR FINISHES i Mortar and Grout for Reinforced Masonry—Specification for. .. .V.STM C 476—63 Mortar for Unit Masonry—Specification for _ ASTM C 27,1

Portliind Ccfncnt—Specification for _...(Sce CONCRETE)

METAL

Alloy Steel Bolts. Qucnclied ami Ti-mpcrcd, for Structural

Steel Joints—Sl.ifsdanl Sl)ccifica!ions for ASTM A 490—65 Aiioy Steel UoUs. nucnciicd and 'rnnpcrcd. for Structiir.tl •Slcci Joints—Staisd.ird Si/cdficaluMis for , .....ASTM A 490—63 Alloy Steel Sheets ami Strip. Kcgidar Otiality Hot-Rollctl and

CoUl-f^ollcd—S|>eC!ficaiion for ..ASTM A 506—64

A!iiminum-A!ioy Bars, Roils. Shapes am! Tulles

Stan. lard Spccific.itton for ASTM B 221—64

Aliimmum-Ailny Br4rs, Rods and Wire

Standrin! Spccifitasions for ASTM B 211 —64 Alunuiiuin-AUov Die and Hand I'orgintjs

St.andard Specifir.itioii^ for '"^^'K^^ Aluminum-.Atlny Pific—Standard .Spcci.*icali<>ns (nr A.STM P, 24!—/>4 Aluminuiti-.MIiiv SIk'cI and Plato—Sianilard Specificalions for .-\STM H 10<)—64 Alumiimni- Ailoy Standard Stnictiirai Shapes. Rolled or E.xtnidcd —St.imiard Specilirations for .„..., ASTM H iW—1>4 Aluminun)-,\lliiy Drawn .Stainless 'l ubes

Standard Spec!fic;iti<in>; I'or .....ASTNf il 2'i>—'>4 A-lanunu)ii-,-\(l'>y Round Welded TubesStandard Specificaliiiiis lor VSTM H .!!3

hi Alnininuni and Aluininurn-.Ailov Weldinit Rods ami Bare

Electrodes—Tintative .Sprtitirations lor ASTM R 2.'!5 —filT Aluminiini-AHiiv Kivet and Cold Mcadini; Wire and Rods

Standard S|)i."Citivali<i!ii for .\STM Pi ,J!()—64

AUiniiniini- Base \Uoy On: Cistino—.Standard .Specifications for. .\S1"M B .H5 —oO Aluminimi- Ba.'.e Mlov Pfrfiianeiif M<dd Caslintts

Stanilard S|R-ci}ication for VSTNt B lO.S—

Alummum- Base .Allov Sand Castings—Sl.indard Specification for .\ST^^ B 26—

Aluminuiii Slidinif tiiass !)ours—Siiecilicaiions for \.\.S!.\ 402 ^—!''65 Aiuminnni VVindows—Specifications fur .,\.-\M.-\ 302 4—!%5

(Continued on next page)

202 NISTNCSTAR 1-1 B, WTC Investigation
Reference Standards of 1965 BOCA Building Code

Exhibit C Material Standards (Continued)

METAL (Continued from previous pate)

Reinforcement, Steel Wire. Coid-Drawn, for Concrete

Specifications for ASTM A 82—62T

Reinforcement, Deformed Steel Wire for Concrete ASTM A 496—64 Reinforcement, Welded Deformed Steel Wire Fabric for Concrete....ASTM A 497—64 Reinforcement—Steel Wire, Welded Fabric, for Concrete

Specificatioas tor .„ „ ASTM A 185—64

Rivet Steel. Structural—Specifications for „ „ ASTM A 141 —S8

Rivet Steel, Structural, Hig!i-St.-englli—Speci.'icaiions for ASTM A '95—59

Rods. Gas Welding, for Iron and Steel—Specifications for ASTM .•V 25! —i6T

Seven- Wire Stress-Relieved Strand, Uncoated, for Prestressed Concrete—Specification for .„ „ AST.M A 416—64 Uncoated Stress-Relieved Wire for Prestressed Concrete

Specification for , . „ ASTM A 421 —6S Sheet Piling, Steel—Specification for _ _.. _ ASTM A 32^5

Steel for Bridges and Buildings—Specifications for ASTM A 7—6iT

Steel Plate. Sheet and Strip, Corrosion-Resisting Chromium

Specification for „ _ ,ASTM A \76—63

Steel Plate. Sheet and Strip, Corrosion- Resisting Chromium-Nickel

Specification lor AST.M .A. 167—63

Steel Sheets and Strip, High Strength Low .Alloy Hot-Rollcil ASTM A 375 —64 Structural Steel—Specifications for „ ASTM A 36—63T

Structural Steel, High Strengtii —Specifications for _ _ AST.\{ 440—63T

Structural Steel, High Slrenglli Low zMloy-Specifications for .ASTM A 242—64T

Stniclura! Steel. High Strength Low Alloy Manganese Vanadium

Specifications for _ _ .ASTM A 441—64T

Steel Structural Rivets—Specification for „ ASTM A 502—65

Structiiral Steel with 42.000 psi Miiilnu:m Yield Point in. .Maximum Thickiicss) —Specification for ASTM A 529—64

PLUMBING AND PIPING

Asbcslos-Cvimcnt Kon-Prcssurc Scwcr Pipe

Specifications for _ ASTM C 42S—64T

Asbeslos-Ccincnt Pressure Pipe—Specifications (or .AST.M C 296—64T

Brass Pi|)c, Seamless Rcil Urass—Si>ccification for... .ASTM li 43—62

Cast Iron Pi))o —Pressure—SpccificaliDiis lor „ _ AST.M .A 377 —57 —Soil Pipe and Fittings —Siiccificxtions for _ .\ST.M A 74 —12 Clay Pipe —Dram Tilo—S|)ccifications for _ .ASTM C 4—<)2 ~Extra Strciiglli— Siiccific:itions for _ .AST.M C 21)0—59T

—-Sewer. Sl.iiuhiril .'^iroiiKth Ceramic 'jl.izcd or L'nglazcil

.SpecifitMi.iMs f.ir _ .ASTM C 20lWV

—Sewer. Stanihird SimiLitl! —Si!i-cilic;uions for „ _ .ASI.M C l.i —37 1'

(Continued on next page)

NIST NCSTAR 1-1B, WTC Investigation 203
Annex A5

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204 NISTNCSTAR 1-1 B, WTC Investigation
Reference Standards of 1965 BOCA Building Code

Exhibit F Durability Test Standards

APPENDIX F

DURABILITY TEST STANDARDS

See alio apfendiza C, D aiut E for tests of mdividual maitriol} or unit asstrnbUei.

CONCRETE AND CONCRETE AGGREGATE

Concrete. Aggregite— Method of Tests for Voids in ASTM C 30—37

Concrete, Air Content of Freshly Mixed, by the Pressure Method—Method of Test for ASTM C 231—62

Concrete. Weight per Cubic Foot. Yield and Air Content oi—Method of Test for _„ ASTM C 138—63

Organic Impurities in Sand for Concrete—Method of Test for , ASTM C 40—60

MASONRY AND MASONRY PRODUCTS

Ceramic Glared Structuri! Clay Pacini? Tile. Facing Brick and Solid Masonry Units

Specifications for (.Autoclave Test) Freezing and Thawing Tests (See Specifications

for Materials) —Bricks—Methods of Sampling and Testing —Drain Tile—Specifications for „ —Structural Clay Tile—Methods of Sainpling and Testing

PLASTICS

Accelerated Weathering Tests of Plastics

Recommended Practice for _ _..ASTM D 79S—57T Water Absorption of Plastics—Method of Test for „ „ .\5TM D 570—63

ROOFING AND SIDING

Asphalt Roll Roofing, Cap Sheets, and Shingles

Methods of Testing „ _ _ _ASTM D 22S—64 Bituminous Materials. Accelerated Weathering Test of—

Recommended Practice for „ ASTM D 529—62

Felted and Woven Fabrics Saturated with Bituminous Substance

for Use in Wat-rproofing and Roofing

Methods of Sampling and Testing ....ASTM D 146—59

UNCLASSIFIED MISCELLANEOUS

Fibre Building Boards—Method of .Accelerated Aging _. _ NBS EMS -1—38 Fibre Building Boards— Method of .Accelerated Aging ASTM D 1037—63T Gypsum Products, Wood Fibre Content in

Method of Test for _ ASTM C 26—59

Textile Fabrics—Method of Test for Water Resistance of -AST.M D 583—63

.ASTM C 126-^2

....ASTM C 67—62 ASTM C 4—«2 ..ASTM C 112—60

NISTNCSTAR 1-1 B, WTC Investigation 205
Annex A5

Exhibit J Unit Design Dead Loads for Structural Design Purposes

APPENDIX J

UNIT DESIGN DEAD LOADS

FOR STRUCTURAL DESIGN PURPOSES

WALLS AND PARTITIONS (Unpkstcred) Poiin<ls per S.juarc Foot

12 inch common brick 120

12 " pressed brick 130

12 sand-!imc brick 105 12 " hollow concrete block—Stone Aggregate., 74 Lightweight 55

10 " hoUow concrete block—Stone Aggregate , 62 Lightweight -J^ 8 " hollow concrete block—Stone Aggregate 50 Lightweight 36 6 " hollow concrete block—Stone Aggregate 42 Lightweight 36 4 " hollow concrete block—Stone Aggregate 27 Lightweight 20

12 " solid concrete block —Stone Aggregate lOS Lightweight 72

10 " solid concrete block —Stone Aggregate 84 Lightweight 62 8 " solid concrete block —Stone Aggregate

Lightweight

6 " •olid concrete block —Stone A^grcgaic

Lightweight . . . . 4 " folid concrete block —Stone Aggregate

Lightweight . . . . 12 " combination brick and clay tile 8 " " " 12 " combination brick and concrete block.. 8 " " •• .. 12 inch load-bearing clay tile 8 " "

' " 6 " " 4 " " " "

10 " non-load-bearing clay tile 8 • 6 " 4 ' " "

2 * 8 " non-ioad-bearing hollow concrete block 6

4 "

" T.C. V/s inch split terra cotta furring 2 inch split terra cotta furring

56 " hollow gypsum block

S4 " " '"

6748

5037

45

34SO

00

72m

40

36

24

40

36

3020

18U

40

3020

.S U)

!224

18

13

10

(Continued on next page)

206 NISTNCSTAR 1-1 B, WTC Investigation
Reference Standards of 1965 BOCA Building Code

Exhibit J Unit Design Dead Loads for Structural Design Purposes (Continued)

Poumls per Square Foot

4 inch solid gypsum block 24

3 " 18 2 " •' " " \2 4 " glass block jg

Potmils per Cubic Foot Ca«t stone solid , 144 GTanite ashlar 168 Limestone ashlar 168 Marble ashlar 168 Sandstone ashlar 156 Rubble stone masonry 156 Terra cotta architectural (filled) 120 Terr» cotta architectural (unfilled) 72 Concrete, stone (plain) 144 Concrete, stone (reinforced) 150 Concrete, cinder 108

Fill, cinder 60 Earth (dry) %

Earth (damp) j08 Earth (wet) 120 Cork 15 Timber. Ash 40 Timber, Douglas Fir 36 Timber, Cypress 30 Timber, Hemlock 30 Timber, Oak 4K Southern Pine, Short Leaf 36 Southern Pine, Long Leaf 48 Redwood 2H Spruce JO

PLASTER WORK Poud.Is per S.junrc Foot Gypsum (one side) >> 5 Cement (one side) U) Gypsum on wood lath S Gypsum on metal lath g Gypsum on plaster board or fiber board 8 Cement on wood lath JQ Cement on metal lath ]Q SUSPENDED CEILINGS Pouivls per S.juare Foot Cement on wood lath 12 Cement on metal lath ]5 Gypsum on wood or metal lath \q

LATH AND PLASTER PARTITIONS Poim.ls per S<nure Foot 2 inch solid cement on metal lath 25

2 " solid gypsum on metal lath 18 2 " " " on gypsum lath 18 2 " metal studs gypsura fk. metal lath both sides IS 3 - " .. " - 19 4" " " MM M • M 20

(Continued on next page)

NISTNCSTAR 1-1B, WTC Investigation 207
Annex A5

Exhibit J Unit Design Dead Loads for Structural Design Purposes (Continued)

Pounds per Square Foot 6 inch wood atudt pluter and wood lath, both aides 18 6 " " " " " meul lath, both side* 18 6 " " « « " pjaiter boards, both tidea 18 6 ** *' ** unplaatcred gypsum board, both sidea (dry wall) 10

FLOOR AND ROOF CONSTRUCTION Pounds per Square Foot Qnder fill per inch depth 5 Cinder concrete per inch depth 9 Stone concrete per inch depth 12 Floor finish tile per inch depth 12 Cement finish per inch depth , , 12 Gypium slabs per inch depth 4 Precast concrete plank per inch depth (aa determined by teat) Hardwood flooring per inch depth , 4 Undcrflooring per inch depth , 3 Linoleum , , 2 Aaphalt tile , 2

ROOFS AND ROOFING Pounds per Square Foot Metal Skylighta 10 J-ply roofing 4

'* 5 5 " " 6 Wood aheathing (I') J Plywood sheathing (5/16') 1 Corrugated iron roofing 3 Formed steel decking 3 Slate tile roofing , , 10 Cement tile 16 Spanish tile 20

Shingles, aabeatoa 6

Shingles, asphalt 6 Shingles, wood , 6

208 NISTNCSTAR 1-1B. WTC Investigation
Reference Standards of 1965 BOCA Building Code

Exhibit K Unit Working Stresses for Ordinary IVIaterials

APPENDIX K

UNIT WORKING STRESSES FOR ORDINARY MATERIALS

Unless otherwise specified herein, the allowable working stresses for ordinary materials, as defined in sections 701 and 722, shall be reduced ten

(10) per cent below the recommended values of the accepted engineerings standards listed in appendix B. When the structural material is identified

in regard to manufacture and grade and the identification is accompanied

by satisfactory mill tests or the strength and stress grade of the materials are otherwise confirmed to the satisfaction of the building ofScial, the allowable working stresses may be increased to compiy with the accepted

engineering standards.

K-1. MASONRY STRESSES

K-l-A. Mortar for Unit Masonry.—Mortar for unit masonry shall comply with either the proportion specifications as set out in section 816.2, or

shall meet the property specifications of the accepted engineering standard

listed in appendix C. Unless laboratory data are presented to show that the mortar meets the requirements of the property specifications, the pro- portion specifications shall govern. K-l-B. Compressive Stresses.—Except as permitted in other sections of the Basic Building Code, the compressive stresses in masonry shall not exceed the foliowing values:

All«w)ble ronpreuite strtuis |r«ss crtss settiSMl »H (iiMpt ]] netid)

Ijpt at Wissxr; iid Crjdi ol Miunry Out Iyp« c! Mortar

Ipsi imi mi) M s N 0

Solid mascnry of bnck )nc other solid units of clay

Of snsie: sane '-imt or concrete; 8000 plus 3S1 Irom iiX to 8000 psi from 230C to 450C psi fion 1500 to 250C psi

psi

400

250

175

125

p«

350

225

160

115

psi

300

200

!40

100

pji

200

150

10075

Gro«!eC masonry of wiid masonry units (fom 450C to 8000 pSi

froni 250C; to ibX jsi trom 1500 to 2500 psi

350

:2i

275

215

175

200

155

125

Sons rnasonry ol soiitf Concrete masonry unitj; :800 plus psi from 1200 to 1800 psi

175

125

160

115

140 100

.300

' 75

Mascnry of hollow jnits 85 75 70

Hollow walls Icavity or rnasotiry boncedi'

SoliC masonry units 2500 51*15 psi from :500 !o 2500 psi Hollow T^swrv units

UO

100

70

i30

90

EC

no

30

55

Stone asJiiar mjsjnry

Granite Lirrestne or nartile Sanditone or cast stane RtCCie ;icne. coj.'sed, rougti o.' random

800

500

400

;4C

720

450

360

121

640

40O

320 100

500

325

240

80

•0*1 gross c'ssjsectisrai area of wall minus area of cavity between yt.ies. "he allowable ^""""'essKe s^r^

for canity walls are OaseC upon the assumption that the floor ioaCs Ijear upon t/u! one !!! of the i'J "TJTM:

Where noilow oails are icaded concentrically, the allowable stresses niay be sncrtased by r«er.ty-f!»e i") P*' ''^

NISTNCSTAR 1-1B, WTC Investigation 209
Annex A5

Exhibit K Unit Working Stresses for Ordinary Materials (Continued)

K-l-C. Shear and Tensile Stresses.—Except as permitted in other sec- tions of the Basic Building Code, the aliowabie shear or tensile stresses in unreinforced brick masonry shall not exceed the following %'3lues:

iUlfKydi itrtiMi li dtar «r ttulei la llHara fir vetMwvU krtek usttni'

£atrtraetlu

ABmM WwUaf Strtsut. pil tns]

Crass-S«cti«ui \s*i. £ici;t as litU^

TypiliirS

rtar

Single wyi^e wslis of solid clay masonry unitst Qf wslls of sroutuj

ftfick nasonry 36 28

Solid walls, brick and othtf solid clay maswiry units, masonry bondsd m metal tieii 23 20

Cavity a«j mastmry^tonded hollow walls, brick and brick** 28 20

•Allowibli stresses to brick and other solid clay mascn/y units laid In Portland cenwnt-Jinn-sand ffloftars.

If other nusi»)ry units or mortars are used, allowable stresses for such masotvy construction shall be esta^

lished by tests ^ified In section 803. "Net area. ' r r

-

K-2. REINFORCED CONCRETE STRESSES

The allowable working stresses for ordinary materials shall be based on

the following proportions by dry volumetric measurement and maximum

water content per sack of cement in accordance with the standard building

code requirements for reinforced concrete specified in appendix B subject

to the ten (10) per cent reduction prescribed for ordinary materials.

2&-4i»y strtngik Gallons of -waiir

of eonereU in ^ fer sack of (tmtut fovndt fer t^uan tWA Concrttt froportiom 2000 . - 1:SJ4 7J4 2500 . . 1:4J4 m 3000 . , $

K-3. REINFORCED GYPSUM CONCRETE STRESSES

When ordinary materials are used, the allowable wor,kiag stresses shall be based on the following proportions, measured dry by weight with suffi- cient water to make a plastic mix that will fill the forms: 100 per cent neat

calcined gypsum ; 97 per cent gypsum and 3 per cent wood chips, shavings

or fibers ; and 87.5 per cent gypsum and 12,5 per cent wood chips, shavings

or fibers ; with ultimate compressive strengths of 1,800, 1000 and 500 pounds

per square inch respectively.

The working stresses shall not exceed the values prescribed in the stand- ard for reinforced gypsum concrete listed in appendix B subject to the ten

(10) per cent reduction prescribed for ordinary materials.

(Continued on next page)

210 NISTNCSTAR 1-1 B, WTC Investigation
Reference Standards of 1965 BOCA Building Code

Exhibit K Unit Working Stresses for Ordinary Materials (Continued)

K-A. 8TSEL REINPOKCEMEKT STSSSSBS

The allowable working; stresses for remforcemeat specified in the stand- ard building code requirements for reinforced concrete listed in appendix B

shall be used in all reinforced construction, including reinforced concrete, reinforced gypsum concrete and all forms of reinforced masonry subject to the ten (10) per cent redaction specified for ordinary, unidentified materials except as follows:

Uoinmum ilrtu Tyft d Stttl Elfmnt 1m pemdj ftr iguar* tuck HIth Yield Strto»th SteeJ (SO per cent of YkU Point) 30.000 Stcd Pipe, CoDcretc-fiUed (45 per cent of Yidd Point) 16,000

K-5. STRUCTURAL STEEL STRESSES

When ordinary materials which are not identified as to manufacture and

grade are used, the allowable working stresses specified in the standard

for the design, fabrication and erection of structural steel listed in appendix B shall be reduced ten (20) per cent.

K-6. CAST STEEL STRESSES

The allowable working stresses for cast steel in compression and bearing

shall be the same as those specified for structural steel and shall not exceed

seventy-five (75) per cent of the values specified for all other applicable

stresses in the standard.

K-7. CAST DtON STRESSES

Uaiimum tiritt Touioa 3,000 Extreme Tcniion (Fiber SircM ia Bendtof) 3,000 Extreme Comprtitioa (Fiber Streii in Beading) 16,000 Shear 3,000

I Column Gimpreuioa 9,000 minus 40—

J , r Ratio — not to exceed •cventy (70)

K-«. OPEN-WEB STEEL JOIST STRESSES

The allowable working stresses specified for open-web steel joists shall be in accordance with the standard specifications for steel joist construction

listed in appendix B. For all other steel joists, unless otherwise specifically approved and identified, the allowable working stresses specified by the standard shall b« reduced ten (10) per cent

K-9. FORMED 8TBBL CONSTRUCTION STRESSES

The allowable working stresses for light gage formed steel structural members shall be based on the following grades of flat rolled carbon steel with yield points of 25,(X)0, 30.(X)0 and 33,0(X) pounds per square inch as

specified in the standard specification for the design of light gage steel structural members listed in appendix B, subject to a reduction of ten (10) per cent on all stress values for ordinary materials.

K-10. LUMBER STRESSES

When the grade of lumber is not identified as provided in section 722 for controlled materials, the maximum allowable working stresses for the species

of lumber used shall be determined in accordance with the principles for

stress grade lumber as set forth in the National Design Specification for Stress-Grade Lumber and Its Fastenings.

NISTNCSTAR 1-1 B, WTC Investigation 211
Annex A5

Exhibit K-11 Earthquake Load Design

K-U. EARTHQUAKE LOAD DESIGN

When required to withstand lateral forces under section 719.0 bixild- ings and structures shall be designed in accordance with the following

sections according to the zone in which they are located on the seismic

probability map in table 14C. K-Ii-A. Application of Provisions.—These lateral force requirements

are intended to make buildings earthquake-resistive. The provisions apply

to the buildings as a unit and also to all parts thereof, including the structural frame or walls, Hoor and root systems, and other structural features. In specific cases, they may be interpreted or added to as to detail by

rulings of the building official in order that the intent shall be fulfilled.

K-ll-A-1. Additions.—Where applicable, every addition to an existing

building or structure shall be ilesigncd and constructed to resist and with- stand the forces provided for herein, and in any case where an existing

building or structure is increased in height all portions thereof affected by

such increased height shall be reconstructed to resist and withstand the forces provided foj; herein.

K-Il-A-2. Alterations.—Where applicable, no existing building or struc- ture shall be altered or reconstructed in such a manner that the resistance

to the forces provided for herein will be less than that before such altera- tion of reconstruction was made; provided, however, that this provision

shall not apply to non-bearing partitions, and shall not apply to other minor alterations which are made in compliance with all requirements of the Basic Code.

K-ll-B. Plans and Design Data.—-Where earthquake loads are applicable, a brief statement of the following items shall be included with each

set of plans filed:

(a) A summation of the dead and live load of the building, floor by

floor, which was used in figuring the shear for which the building

is designed.

(b) A brief description of the bracing system used, the manner in which

the designer expects such system to act and a clear statement of any assumptions used. Assumption as to location of all points of counterflexure in members must be stated. (c) Sample calculation of a typical bent or equivalent. For combined

stresses due to the lateral forces and other loads, the allowable unit

stresses and the allowable load in connections may be increased as provided in section 720.0.

K-ll-C. Lateral Force Requirements.—Where earthquake loads are

applicable, every building or structure and every portion thereof, except

as exempted in section 719.1 shall' be designed and constructed to resist stresses produced by lateral forces as provided herein. Stresses shall be

calculated as the effect of a force applied horizontally at each floor or

roof level above the foundation. The force shall be assumed to come from

any horizontal direction.

K-ll-C-1. Bracing Systems.—All bracing systems both horizontal and

vertical shall transmit all forces to the resisting members and shall be of

sufficient extent and detail to resist the horizontal forces provided for herein and shall be located symmetrically about the center of mass of the building or the building shall be designed for the resulting rotational forces about the vertical axis.

(Continued on next page)

212 NISTNCSTAR 1-1 B, WTC Investigation
Reference Standards of 1965 BOCA Building Code

Exhibit K-11 Earthquake Load Design (Continued)

K-ll-C-2. Junctures Between Wings.—Juncturch l)ctwecn distinct parts

of buildinjjs, such as winjjs which extend more th;in twenty (20) feet from

the main portion of the buikiin;j, shall be desijjncil at the juncture with

other parts of the buililing for rotational forces, or the juncture may be made by means of sliding frajriie joints having a minimum width of not

less than eight (8) inches. The details of such joints shall be made satis- factory to the building official. K-ll-D. Horizontal Force Formula.—The horizontal force shall be cal- culated according, to the following formula:

F= CW

Where

F = the horizontal force in pounds.

W — the total dead load, tributary to the point under consideration,

except for warehouses and tanks, in which case W shall equal

the total live load tributary to the ix>int umler consideration. Machinery or other fixed concentrated loails shall be considered

as part of the dead load. C = a numerical constant as shown in table 14B and section K-ll-D-l

to Kll-D-3 inclusive.

TABLE 14B^H0RlZ0iSTAL FORCE FACTORS

Part or Portion Value of C

in Zone 1* Direction of Force

Floors, roofs, columns and bracing in any story of a

building or the structure as a wihole** O.IS'" N +4'/$

Any

direction horizontally Bearms walls, non-t>caring walls, partitions, free standing masonry walls over 6 ft. in height

.OS With a mini- mum of five pounds |}er

ft.

Normal to surface of wall

Cantilever parapet and other cantilever walls, except

retaining walls .2S Normal to surface of wall

Exterior and interior ornamentations and appendages .25 Anydirection horizontallv When connected to or part of-a building: towers,

tanks, towers and tanks plus contents, chimneys, smokestacks and penthouses

.05 Any

direction horiiontally Elevated water tanks and other tower-supported

structures not supported by a building -03 Any

direction horizontally

*For. toocB, •«« t&bl« t4C. For r«qut/«m«nu in tone* tct icclion K-ll-D-1 to K-ll-D-J ioclutivc. "Where ipcciftcd wind loid would produce higher itreuct, thU load ihill be lucd in lieu ol the

ftclor ihowa. (S*< section 720 0.) ***N u number ot itariei above the iiery under cooiidcratioB, proTidetl that for Soon or horiiootal bracing, N iKall be onl; the nuraber of ttoriei cooiributing loadt. K-ll-D-1. Requirements for Zone 1.—Where earthquake loads are applicable to buildings or structures in Zone 1 on map in table 14C, the value of "C" shall be as shown in table 14B. K-ll-D-2. Requirements for Zone 2. —Where earthquake loads are applicable to buildings or structures in Zone 2 on map in table 14C, the value of "C" shown in table 14B shall be doubled.

K-ll-D-3. Requirements for Zone 2.—Where earthquake loads are applicable to building.s or structures in Zone 3, on map in table 14C, the value of "C" shown in tabic 14B shall be multiplied by four (4). K-ll-D-4. Location of Zones.—For the purjwsc of determining the value of "C" in table 14B, the map in table 14C shall govern.

(Continued on next page)

NISTNCSTAR 1-1 B, WTC Investigation 213
Annex A5

Exhibit K-11 Earthquake Load Design

K-ll-E. Foundation Tics.—Where earthquake loads arc applicable in the (iesiijn of builifings, other than lightly loaded structures of type 2 and

4 construction, where the foundations rest on piles or on soil havinjj a safe

bearinfj value of less. than two ihousanil (2000) pounds per s<|uarc foot, the foun(!ati<jns shall be completely intcrc<jnncctcd in two directions ap- proximately at right anjjles to each other. Each such interconnecting

member shall ite capable of trnnsmittinfj by both tension and compression

at least ten (10) per cent of the total vertical load carried l)y the heavier

only of the footings or foun<lations connected. The minimum jjross size of each such member if of reinforced concrete shall be twelve (12) inches by twelve (12) inches and shall be reinforced with not less than the minimum rcinfurcement specihcd elsewhere tn the Basic Code. If the

interconncctinij members are of structural steel, they shall be designed

as provided cl.sewhere in the code, and cncascf! in concrete. A reinforced

concrete slab may be used in lieu of iinterconnecting tie members, providing the slab thickness is not less than one forty-eig^hth (1/48) of the clear distance between the connected foundations; also providing the thickness

is not less than six (6) inches. Interconnecting slabs shall be reinforced with not less than eleven- hundredths (.11) square inch of steel per foot of slab in a longitudinal

direction and the same amount of steel in a transverse direction. The

bottom of such slab shall not be more than twelve (12) inches above the

tops of at least eighty (80) per cent of the piers or foundations. The

footings and foundations shall be tied to the slab in such manner as to be

restrained in all horizontal directions. K-ll-F. Bonding and Tying.—Where earthquake loads are applicable, cornices and ornamental details shall be bonded into the structure so as

to form an integral part of it. This applies to the interior as well as to the

exterior of the building.

K-U-F-1. Veneer Ties.—Veneer tics shall be of sufficient strength to support four times the weight of the attached veneer. K-Il-G. Overturning Moment.—In no ca.sc shall the calculated over- turning moment of any building or structure due to the forces provided

for herein exceed two-thirds (^) of the moment of stability of such

building or structure. Moment of stability shall be calculated using the same loads as used in calculating the overturning moment for wind forces.

214 NISTNCSTAR 1-1B, WTC Investigation
Reference Standards of 1965 BOCA Building Code

NISTNCSTAR 1-1 B, WTC Investigation 215
Annex A5

This page intentionally left blank.

216 NISTNCSTAR 1-1B, WTC Investigation
Annex B1

Tables in 1 968 New York City Building Code

B1.1 EXHIBITS

TABLE 9-1 Percentage of Live Losid

Gantributoo' Area Ratio of Live Load to Dead Load * (Sq ft ) 0.625 or less 1 2 or more

]49 or le3» 100 100 100 ibO-299 80 85 ^

300-449 60 70 7S 450-599 50 70

600 or more ^ . . 40 5S «

Note:

a. For imermediatc values of live knd/dead load, the applicable pcrcenta£:es of live load may be interpolated.

TABLE RS 9-5.1 DESIGN WIND PRESSURES ON VERTICAL SURFACES

Design Wind Pressure on

Height Zone Vertical Surfaces (pif of

(ft. above curb level) projected solid surface)

Structural Panels frame Glass

0-50 (signs and similar constructions of shallow

15 0-100 .......... 20 30

101-300 30 301-600 30 35 601-1000 35 40

Over 1000 40 40

NISTNCSTAR 1-1B. WTC Investigation 1\1
Annex B1

TABLE RS 9-5^ DESIGN WIND PRESSURES ON HORI7X>NTAL

AND INCLINED SURFACES

Roof Slope Design Wind Pressure Norma! to Surface

30 degrees or less Either pressure or suction equal to 40 per cent of the values in Table RS 9-5.1 over the entire roof area More than 30 degrees Windward slope — pressure equal to 60 per cent of values in Table RS 9-5. 1

Leeward slope — suction equal to 40 per cent of

values in Table RS 9-5.1.

TABLE RS 9-5J SHAPE FACTORS

Construction Shape Factor

Signs (and their supports), or portions thereof, having 70 per cent or more of solid surface 1.5 Signs (and their supports), or portions thereof, having less than 70 per

cent of solid surface 2.0 Tanks, cooling towers, and similar constructions 1.5 Upright, circular cylindrical surfaces . 0.7 Square and rectangular chimneys 1.5

218 NISTNCSTAR 1-1 B, WTC Investigation
Tables in 1968 NYC Building Code

* TABLE lO-I INSPECTION OF MATERIALS AND ASSEMBLIES

Materials lilcincnis Thai Shalt he

Subject to Cottlrolled

Insprction*'^-^

Elements That A re Not

Subject to Controlled

Inspection'-'-^

Steel

Concrete

Aluminum

Wood

Reinforced

gypsum

concrete Masonry

Other

None

Materials for all structural elements proportioned on

the basis of calculated

stresses 70 per cent or

greater, of basic allowable

values. See Article 5

for specific requirements

relating to "quality control of materials and

batching."

None

None

All structural ciments and connections.

( 1 ) Ail materials for structural elements proportioned on the

basis of calculated stresses

less than 70 per cent of basic allowable values. (2) Concrete materials for; (a) Short span floor and roof

construction proportioned as per section 27-610

(b) Walls and footings for

buildings in occupancy group

J-3. (3) Metal reinforcement.

All structural elements and connections. AH structural elements and connections.

None All structural elements. None All structural elements. Requirements as may be established in other articles of this code

or by the commissioner.

Notes:

• For general provUioiB relating to inspection vx section 27-1 32.

k All structural tnaienals and aucmblies subject tocontrolted inspection shall be tested and/ or

inspected at their place of manufacture arnl evidence of compliaitcc with the provisioiu of this subchapter shall be provided as stipulated in articles four through twelve.

^ Mill, manufacturer's aitd supplier's inspection and test reports will be accepted as evidence of compliance with the provisions of this code for all structural materials and assemblies not subject

to controlled inspection.

' Basic allowable stress values as referenced herein shall denote allowable stress value without

iiKrcase for infrequent stress conditions as established in this code or in ihc applicable reference standard for the material or element in its proposed use.

NISTNCSTAR 1-1 B, WTC Investigation 219
Annex B1

^ B 5

1 cl

, a. ^0

11^

ii C

S

^

u u a a 5c.

a* « V 2 *-

p

5 s

s

.s * <§-M°

a « U

l-p J« «! If

•J g -S ^ J = ^ I

'|lii»!i|t-s|f

si

o ^

^

^ ^ "o

KQ = E

u ,0ft *iO

<E 6

i 3 C j

S ?. i ^-2 S § - 5 i1

1«

,2 « a. ||S

51-1

.£ e e g

„ « s

"= 8s

i < . « O ^ 5= Ill

.8 S E

>-'5

-Si S is

si

ll

ll

Hi 1^a. 'a

ill

s i -s-S

J 8 8

f|

lit

III

.S 8 I

ilk

220 NISTNCSTAR 1-1 B, WTC Investigation
Tables in 1968 NYC Building Code

Tabic 10-3 Minimum Cement Factor

Specified Comprchcnsjve

Strenffth in 28 Days

(f'.)-psi

2.000 2.500

3.000

3.500 3.750 4.000

5.000 Over S.OOO

Minimum Bags of Cement

Cubic Yard of Concrete

(all aggregates)

^ 5.00

' 5.25

5.75

6.50

6.75

7.00

7.50

Permitted only by Method TI

NISTNCSTAR 1-1 B, WTC Investigation 221
Annex B1

zvn

zs\r.

J Si

n

i n

l3

31

I n«i •A'U ««aik>«u «u murtvmi i * I tNt4-*1U> MS m

mi

tii : .

-f,i:ii

II 15

1 aiuM) ja n«

! alii

Sit

t . . f'il lln

m

111h

n

jiii

1 •it

liiiif

i

^ 111 pi

ihvm

mm

5I;

•Jh

1 iijljiMI li^ll

. t, '^i:is{Sil5i'«

{

r

i'i

Ji

Si. Ill

Itt

«'M' •

iii-i' i'nm

Mil

J in

1! f!MI

w lip = I!

1 .1

222 NISTNCSTAR 1-1 B, WTC Investigation
Tables in 1968 NYC Building Code

Table U-2 Allowable Soil Bearing Pressures

Qais o( Description Basic Allowable Bearing Values

Material See Note (1) (Ton* per $<i. ft)—See Note* CIO). (U) and (12)

1-65

2-65

i-6S 4-65 5^5

6-65

7-65

8^5

9-65

10-65

11-65

Hard SouikI Rock 60 Medium Hard Rock 40

lotennediate Rock 20

So(t Rock 8

Hardpoa Cravd and Gravd Soils (Soil Groups GW. CP. CM & GC

and soils of Soil Groups SW.

SP, and Shi containing more

• than 10% of material retained on a Na 4 sieve) —

Sands (other than Fme Sands) (SoU Groups SW. SP & SM

but containing not more than 10% of material retained on

a Noi 4 sieve) —

Fine Sand —

Oars and Oay SoUs (SoU

Groups SC. (X & CH)

Hard 5 Medium 2

Soft See

Silts and Silt Soils (Soil Croopa l£L & MH)

Dense 3 Medium 13

Loose Sec

Nominally Unsatisfactory Beariag Materials See

See Notes (2) and (8). SeeNotes(2)and(8).

See Notes (2) and (8). - See Notes (3) aud (8).

See Notes (4) and (8) and (9).

See Notes (5). (8) and (9). See Nous (6), (8) and (9).

See Note (7). See Note (7). Sec C26- 1103.5.

Sec C26- 1103.5.

SecC26-na3i.

Notes:

(1) Gmirw-irioa—The soil classifications indicUed in this table are tbose described

in lectiao 1103.L Wbere there is doubt as to the applicable clauificatioo cH a soil irtratuin.

the allowabtc bearing pressure applicable to the lower class of material to which the given itratum misht conform shall apply unless the conformance to the higher class of material can be proven by laboratory or field test procedures.

(2) Allowable bearing pressure on rock. —The tabulated values of basic allowable bearing pressures apply only (or massive rocks or, for sedimentary or foliated rocks, where the strata are level or nearly so, and. then only if the area has ample lateral support. Tilted strata and their relatioa to nearby slopes or ezcavationj shall rcixive special

eonsideration. (3) Allowable bearing pressure on hardpan. —For hardpan corisisting of wdl cemented

material composed of a predominantly granular matrix and free of lenses of fine grained

material and inclusions of soft rock, the basic allowable bearing pressure shall be 12 ions

per sq ft. For hardpan ccrsisting of poorly cemented material or omtaining lenses of

fine grained material, inclusions of soft rock, or a fine grained matrix, the basic allowable bearing preuure shall be 8 tons per sq. ft

(4) Allowable bearing pressure on gravel and gravel soila—V^ues of basic allowable bearing pressure shall be as follows

(a) For soils of Soil (Jroops GW, GP. CM, and GC:

Compact, well graded material—10 tons per sq. fL Loose, poorly graded material—6 tons per sq. ft Intermediate cooditiors—Estimate by interpolation between indicated extremes.

(Continued on next page)

NISTNCSTAR 1-1 B, WTC Investigation 223
Annex B1

Table 11-2 Allowable Soil Bearing Pressures (Continued)

{b) For »oil» of Soil Croupt SW, SP. »nd SM, eontiintnjt more than 10% of

material retained on a No. 4 litre:

, , Compact, weli graded material—8 tew* per sq. ft

Looae, poorly graded material—4 4on« per sq. ft

Interttiediate cooditiotu—Estimate by interpolation between indicated extreme*.

(5) Aiiowable bearing prciiure on landa,—The basic allowable bearing pressure shall be determined from the resiMance to penetration of the standard sampling spooa Tlie

b.tsie allowable bearing pressure in tons per jijuare foot shall equal 0.10 times N but not greater than 0 tons per square foot, nor iesi than 3 t^s per square foot The appropriate value for the penetraticm resistance at various areM of the site shall be made by averaging

the measured resistance within a depth of soil below the proposed footing level equal

to the wid^i of the fooling. Where the average values so obtained do not vary by more than 25 per cent of the minimum of the average values over the site of the proposed building, the lowest average value shall be used for the design of the entire building. V^'hcre the variation exceeds 25 per cent, the allowat^e bearing pressure shall be predicated on the lowest average value unless appropriate measures are taken to avoid

detrimental amounts of differential seftlemcnts of the fot^ings. When; the design bearmg

pressure on soils of class 7-<5 exceeds 3 tons per square foot, the embedment of the loaded area below the adjacent grade shall not be less than 4 feet and the width of the loaded area not less than 3 feet unless analysis shall demonstrate the proposed construction to have a minimum factor of safety of 2.0 against shear failure of the soil. (6) Allowable bearing prosurc on fine sand.—The basic allowable bearing pressure

shall be determined frmn the resistance to penetration of the standard sampling spoon. The basic allowable bearing pressure in tons per square foot shall equal 0.10 times N

but not greater than 4 tons per square foot nor leu than 2 tons per square foot except

that, for loose materials (resistance to penetration of the standard sampling spoon 10 blows per foot or less), where the foundataon i* st^jected to vibratory loads from machinery or similar cause, the indicated buic values shall not apply. The allowable bearing pressure shall be established by analysis applying accepted principles of soil mechanioi and a report of such analysis satisfactory to the commissioner shall be submitted as a

part of the application for the acceptance of the plan*. (7) Allowable bearing pressure oc days and clay soil*.—The bearing captdty of medium and hard clays and clay s«ls shall be otablished on the basis of the strength

f.

' of Kiefa scmIs as delermined by field or laboratory tests and shall provide * factor of

safety against failure of the soil of not less tlian 2j0 computed on the basis of a recogntied procedure of soils analysis, shall consider prisbable settlements of the building, and

shall not exceed tlve tabubied maximum values. (S) Increases in allowable beanng pressure due to enibedmeni of llie foundation.

(a) The basic allowable bearing values for rock of classes 1-65, 2-65 and 3-65 shall apply where Hit loaded area is oii the surface of sound rock. Where the loaded area is below

the adjaccni rock surface and is fully confined by tlie adjacent rock mass and provided

that the rock mass iias not been shattered by blasting or otherwise is or has been ren- dered ur«5ouiid, Ihcsc value* may be increased 10 per cert of Ac base value for eadi fool

of cmbcdnteiit iK^ov. tliC surface of titc adjacent rock surface in excess of we fool, but shall not excecil twice the basic values, (b) The basic allowable bearing values for

soils of classes 5-65 through $.65 determined in accordance with notes (3), (4), 'and

(5) above, shall apply wlierc tlic loaded area is embedded 4 ft or less in tlie bearing

stratunj. Where the loaded area li embedded more tlian 4 ft below llic adjaccni surface of the bearing stratum, and is fully confined by the weight of the adjacent soil, these values may be increased 5 per cent of the base value for each foot of additional embedment, bat shall not exceed twice tlie basic viues. Increases in allowable bearing pressure due to cmbedmcns shall not apply to soils ol classes 4-65, 9-65. 10^5, or 11-65. (9) laCTcaK in aJtowabk bciriiij: pressure for limited depth of bearing stratum.

The allowable bearing values for soils of classes 6-65, 7-65 and 8-65 detctmined in accordance with this table and the notes thereto (including note (8)), may be increased up to one-third where the density of the bearing stratum below the bottom of the footings or the tips of the piles increases with depth provided that: (a) The bearing stratum is not underlain by materials of a lower dass. (b) The allowable bearing value of the soil material underlying tlie bottom of the footings or the tips of the pDes increases at least SO per cent within a depth below the footing or the tips of the piles which is not greater than the width of the footing or the width of the polygtKi dmunscribing the pile group.

224 NISTNCSTAR 1-1B. WTC Investigation
Tables in 1968 NYC Building Code

Tabic 11-4—Utremum Drivinf Rcsistuxx and Uiniraum Hammer Eiwrgy for Slee! K>

Files, Pipe Pile*, Precast and Cait-in-Place Concrete Piles and Gnnpoiite Piles (other than timber)

Minimum Drivinf Resistance** ** * NoR-Di»- Di*-

ptacecneot pjactment

Piles Pile*

Piles Bearing on Bearing on

Bearinc on Decomposed Decomposed Piles Bearing

Kardpan Rock Rock on Rock

Pile Hammer* Friction (SoaOau (SoU Qass (Soil Qass (Soil Classes Capacity Eoercr Piles 4-«) 4-iS) 1-65,2-65.

(tons) (ft n>«.) (WowVft.) (Mows/ft) (ktows/ft) (blowi/ft) 43-65)

Up to 20 19 19 4S 48

19.000 IS 15 • 27 27

24.000 11 11 16 16

30 IS.OOO 30 30 72 72 19^00 23 23 40 40

24,000 18 18 26 26

40 IS.OOO 44 SO 96 96

19,000 32 36 S3 53

24.000 24 30 34 34

SO 15,000 72 96 120 120 5 Blows

19,000 49 54 80 80 per % inch

24,000 3S 37 60 60 (Minimum

32.000 24 25 40 40 hammer

60 ISJXO 96 240 240 energy of

19.000 63' ISO ISO IS.OOO ft. IbsL) 24,000 44 100 100

32.000 30 SO SO

70 it 80 19.000 24.000 32.000

5 Blows

per yi inch (Uinimum hammer

energy of

5 Blows

per J4 inch (Minimum

hanuner

energy of

IS.OOO ft lbs.) 19.000 ft Iba.) 100 Over 100

NOTES:

' Final driving resistance shall be the tarn of bbulated values plus resistance exerted by non-boring materials. The driving resistance of non-bearing materials shall be taken

as the reiiitance experienced by the pile during driving, but which will be dissipated with time and n-.ay be approximated as deicribed in Section C26-lI07.1(c)(l)a. *The hammer energy irtdicated is the rated energy.

' Sustained driving resistance—where piles are to bear in soil classes 4-65 and 5-65. the minimum driving reiislance shall be maintained for the lajt 6 inches, unless a higher

sustained driving resistance requirement is established by load test Where piles are to bear in soil classes 6-65 through 10-65, the minimom driving resistance shall be maintained for the last 12 inches imless load testing demonstrates a requirement for higher

sustained driving resistance. No pile need be driven to a resistance to penetratirai (in blows per inch) more than twice th* resistance indicated in this table, nor beyond the point at which there is t» measurable net penetration under the hammer blow. 'The tabulated values assume that the ratio of total weight of pile to weight of

striking part of hammer does not exceed 3.5. If a larger ratio is to be used, or for other

conditians for which no values are tatxilated, the driving resistance shall be as approved by the oonusissioner. 'For intermediate values of pile opacity, tninttnum requirement* for driving re- sistance ma.v be determined by straight line interpolation.

NISTNCSTAR 1-1B, WTC Investigation 225
Annex B1

Table U-S Muiimum Driving Resistamce and Hanuner Energy for TLmber Pilei

Minimum Driving Reaistmnce (Wowi-in.) to be added to driving Hanimer

resistance exerted by ooo-bearing Eitcrgy

Pile Capacity (tons) material* *• (ft-Iba.)* Up to 20 Over 20 to 25

Over 2S to 30

Greater than 30*

Formula in Note * shall apply 7.500-12,000 9,000-12.000

14,000-16,000

12.000-16.000

(single-acting hammers)

15,000-20.000

(ticwbtc-.TCting hammers)

NOTES:

• The driving resistance exerted by non-bearing materials is the resistance experienced

by the pile during driving, but which will be dissipated with time and may ke approximated as described in Section C26-U07.l(c){l)a.

*The hammer energy indicated is the rated energy.

• Sustained driving resistance.—Where piles are to bear in Soil Qasscs 4-65 and

5-65, the minimum driving resistance shall be maintained for the last six inches, unless a higher sustained driving resistance requirement is otablished by load test. Where

piles are to bear in Soil Classes 6-65 thru 10-65, the minimum driving resistance measured in blows per uxrh shall be maiiWained for the last 12 inches unless load testing demonstnvtes a requirement for higticr sustained driving resistance. No pile need be

driven to a resistance to penetration (in blows per inch) more than twice the resistance india^cd- in this Table nor beyond the point at which there is no measurable net penetration under the hammer blow. *The minimum driving resistance shall be determined by the following formula; „ 2W»H „ 2E

* ~ or P = s-}-0.1 where:P sAUow^le pile load in pounds.

W, s= Weight driven in pound*.

Wk = Weight of striking part of hammer in pounds.

s-ffll

226 NIST NCSTAR 1-1B, WTC Investigation
Tables in 1968 NYC Building Code

TABLE 1 1-6 BASIC MAXIMUM PILE IX)ADS

Type of pile

Basic niuxiittum pile loud

(lorn) Caijtson piles Opcn-cnd pipe (or fuhc) piles bearing on rock

of classes 1-65. 2-65. and 3-65 Closed-end pipe (or tube) piles. H piles, cast- in-placc concrete and compacted concrete

piles bearing on rock of clas-sc; 1-65, 2-65,

and 3-65

Piles (other than timber piles) hearing on soft rock (class 4-65)

1 ) Displacement piles such as pipe, cast- in-placc concrete, and compacted

concrete piles

2) Non-displaccmcnt piles such as open- end pipe and H piles Piles (other than timber piles) bearing on

hardpan (class 5-65) overlying rock

Piles (other than timber piles) that receive

their principal support other than by direct bearing on soik of classes I -65 to 5-65 Timber piles

Bearing in soils of classes 1-65 to 5-65 Bearing in soils of classes 6-65 to 10-65

No upper limit 18 in. O.D. and greater - 250

less than 18 in. O.D. -200

150

60

80

100

60

25

30

NISTNCSTAR 1-1B, WTC Investigation 227
Annex B1

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228 NISTNCSTAR 1-1B, WTC Investigation
Annex B2

Tables in 2001 New York City Building Code

B2.1 EXHIBITS

In addition to all the tables listed correspondingly in Annex Bl, the following table is added in the 2001

New York City code.

Specified compressive

strength in twenty-eight

days if 'c) pounds

per square inch

2000

2500

3000

TABLE 10-3Jl

Minimum pounds of

cement per cubic yard

ofconcrete

520

560

610

Maximum permissible

total volume of water,

U.S. gallons per cubic

yard ofconcrete _

4142

NISTNCSTAR 1-1B. WTC Investigation 229
Annex B2

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230 NISTNCSTAR 1-1 B, WTC Investigation
Annex B3

Tables in 1964 New York State Building Construction Code

B3.1 exhibits

TABLE C 304-2.2. (1-833) UNIFORMLY DISTRIBUTED AND

CONCENTRATED UVE LOADS

Occupancy or U3«

Unilormly

diathbutod

loads, ptl

ConconLratAd loads

in pounds CI Buainssa BuiinoM machiJi* •nulpment

Oliico spaco . - C2 M«rcanUl«

Storu. shops lor display and aala

Retail On ground Door On uppar floors f^olasale , . —

C3 Industrial Bakari«s Laundrias Manulocturing or processing

Light manulocturing, cnaambly, etc. C4 Storogo Cold Sloraga No overhead 3T=teni_ O'arhaoKi syslern Floor Hool . Light storage Heary storage Paper - .. - n —

CS Asaesiblr Assambly halls, auditoriums. holooiUee. dub

rooms, dance balls. ezhibiUaD hails« grandstands, gyroaasiums. lodge rooaa, museums,

' realauronts. shelters lor air rakia. stadiums. &eatera

Aisles, crossorers. lobbies, Ya(nllorie3____

Main fioors. balconiea Fixed seats . MoTobW svots Pre—jpg rooms

4

.Pn,'jei.tl<j<i rooms

Stcige fleon

Collegea. echoola (cKclusive ol donnlioriea} Oasaroovis

Laboratories „,. Lecture hfilH

Ftaced eeots Movable seats _______

Places oi -worihip Fixed eeots MoToble a«at3 CS Insfltutlanal Hospitals CUiOcs

Corridors, oboire liral noor_ Examination rooms

Laboratories, dark r»>om3 Operating room:: PriTOle roomn

Public space

Soloriums Wards

X-roy rooms, iron :!cr rcon:r,. control ::pac<?s

OrphoTKiges. inhrmori?:; P-tMl instituticns. police lockup :. r-."!'>rin«>twics Cell blocks . Shops ... —

10050'

1007S

120

ISO 100

12575

•iOO

ISO 250

120 2S0

100 60*

10040

100

ISOSO

60

60

100

60

100

6040

60

100604075

60

40

10040

40

40

80

1000

2.000

NISTNCSTAR 1-1B, WTC Investigation 231
Annex B3

TABLE C 304-2.2. {1-833} UNIFORMLY DISTRIBUTED AND

CONCENTRATED LIVE LOADS Continued

Occupancy or uao

CZ'Orsoofi'*

in |y>urKis

200 zooo

100 2,000

<«j 2^ <»» 303

ioo

IIXI

SO" 2,000" 175 12.000** m

\m

250"

100

60

IOO7560

60

60

fiO

«•) .200

300 12J90D" 100"

lOO*

60

250 ^090

80

Spaces common to above occupancies

Air conditioning space.

Corridors

First floor Other lloors Elevator machine rooms

Exitwcrys , , Fan rooms Garages and rampa. open dock parking struciures: Cars, passenger

Busse.'i, trucks, mixed usage

Incineralor charging floor Kitchens (oliier tbon domoslic)

LaboratoT'i?'; ___„_

Ubrories

ReodirKf rooms

Stacks

Ldsbic:: Locker rooms Marquees

Promenades

Rest rooms _ Roola ur,«d eta promenodea

Other roots Sidewolk:: over vautti. Skylight screeas

Storirwoys Terrace:^ yorda. tor ped«itri<m.-<. Toilet rooms

Vaults, in oUic* apace__

WorL-inorM „

* CrcMKblotMb. ItX) fsdi 3«« seellof) C 3(H-9« iof hsriaooial ttsfMb! loodc

* Ual««. ncA^ «Im«W« m Uiis yOaU, 100 eorrUbn >»«hl» « t«aa>cr Be* Um tKat eocMptmcy i«r»iiid. * For kxxis. M« Metfaw C 30i-I t. * WW. <IUm i^HbX cl fjwtg-i -wtfone, mcar^ 7 I««t, load for btaa««, txwA* <snl

i«»i»"<i uxxM citoU Im toMd,

' 33 pi! )M< «| h^tn. w«h a uininum oi ISfl jist

* Cn" avetttm C 304<tOe lor muuBiun itapoavd loodi Iw too'.s. * ^,u^n>]^1l oi aUOn M«<1 ilMt'nMKl only i«r taiilenai Vood.'

'.*. ^f>^ J^«>«=«i SO t>w CMS i«r l«wcl. wh«A.»«t is ioinv.

... roiU ot hiAiw. »Md t* <J«:ifln«l ooly !» 80 pouna* «t CMt« ot •vary naw

" r int b-.ukSiag vImt* o floor 5<ri« may b« l>roc<])il into building.

'« .^ikrlKjht icfcm H> tjOT. -^-UxM to 1-Ind» awrit: uppw^ (eTeen te b* 4 to 10 iacikM obo*« -jlnn and to •ovethmn en l<l«nUcaJ ovounL Ho iinUorm load iMvd h« ImtutmI.

232 NISTNCSTAR 1-1B, WTC Investigation
Tables in 1964 NY State Building Construction Code

TABLE C 304-3. {11-833) SNOW LOADS

In pounds per square fool

Zone Roof slope from horizontal' nuinbera on anew 0* 20* 30" 40" SO' 60" or map mor«

20 ' 20 18 11 6 4* Q 25

' 25 22 14 7 3 0

30 30 27 17 9 3 0 35 35 31 20 10 4 0 40 40 35 . 23 12 4 0 45 45 40 25 13 5 0 50 50 44 28 !5 5 0 SO 60 53 34 18 6 0 70

80'

90'

' Fot nlnlmum Iropoaed Ioad«. zoo locUon C 30 t-10c.

' Tor slope* bolweon iho«o tabuialod, compuso loarfs by .-.iroliht-lino Intorpolaiton.

• Tor »now zone* 70, 80, and 00 on snow map, n»« jams lobular ynlu«« oa

lor zona 60.

* For mow lonot 30 and 2S on mow map, uia lama lobular valuai at lot lona 30, SNOW MAP OF NEW YORK STATE

NISTNCSTAR 1-1 B, WTC Investigation 233
Annex B3

TABLE C 304-4a. (111-833) WIND LOADS: WALLS,

EAVES, CORNICES, TOWERS, MASTS AND CHIMNEYS

In pounds per square loot

At height above grade^

in .'cot

^4 oliS * Eaves end

cornices ' Towers, mcsts end

chimneys

501 lo 500' - 34 68 60 401 to SCO 33 68 58

301 to 400 32 64 55

7.01 )o 300 30 60 S3

101 !o 200 23 55 49

CI lo 100 24 48 42

41 to SO 21 42 37 26 !o 40 18 36 32

16 to 2S 15 30 26

0 !o i5._ 12 24 21

' 'Ixi-r.'ior wolis fliiali bo capable o! witlislandlng vlnd 3oad on both t!i«

ifiloti'jr nod nxtorior aurfacc!;. cciin'j non-slmuUGnoousSy. Tabular valuaa

f.rn ioT r,qi:a:<) or loctanTuior structures. For olrucluroo hoxagcno! or

oc-!a'ioi-.ol m plcin, uno proioctod area and tnuillpif tabuSor vo!uo» by

0 3: lor airucl'uua round or elliptical In plan, use projoclod atea and

r«;:i!ip!y '/oiuoa by C O. For tcnls, ilio wind prpsstiro sha)! bo 10 fsl on Iho

rioj'Scioc! area.

- I.ccd ccsinfj upv/ard.

^ Tor lioinhta obovo ^rado yroalor than GOO fool, add 1 p»f fo load lor woUa

:or ooch intnrvol or part ol inlervol q( 2£30 ioot above 800 !«eJ; lor ocvc* and comicos. and lowers, ina«(a and chimncya, corresponding locds are in

i::<M oiiior. lo 'iioso lor wol!.-,.

234 NISTNCSTAR 1-1B, WTC Investigation
Tables in 1964 NY State Building Construction Code

TABLE C 304-4b. (IV-833) WIND LOADS: ROOFS

In pounds per squaro fool

Mean

olovatlon ol roof abovo

giado lovol

In feet

Direction

of lead'

Slope from horizontal'

0" 10 20° "2Q" iQ 30°

5ul to dUD Dcwnword 8 8 8 to 24 24 Upward 29 29 to 24 24 24 4U1 to ouu Downwcard 8 8 3 to 23 23 Upward 28 28 to 23 23 23

Jul t0 4UU Do'wn'ward 7 7 7 to 22 22 Upward 27 27 to 22 22 22

2C' to 300 Downward 7 7 7 to 21 21 Upvard 25 25 to 21 21 21 101 to 200 Dovmwcsrd 6 6 6 !o 20 20 Upward 24 24 !o 20 20 20

61 to 100 Downward 5 5 5iol7 17 Upward 20 20 to 17 17 17 36 to 60 Do-wnward 5 5 SlolS 15

• Upward 19 19 to 15 15 IS

21 to 35 Downvrard S 5 5 to 14 14 Upward 17 17 to 14 14 14 Oto 20 Downward 5 5 5 to 11 11 Upward 14 14 to 11 11 11

' Dcwr.vfcrd and upward loads act noTi-slroullonooiialy.

' for 3lopo» bolwoon 20* and 30* wUli wfnd acting upward, end botwoen

30* end (jC* with wtnJ ccilnij downward, compxuo loadj by aliaighl-llno tntorpotaUon.

' ro." hoigiita cbovo ^rcdo oioa'.oi l>iar. 000 leol. odd 1 pal lo t:pward toad

lof 0* to 20* alopo ior oach Intorval or pari ol Intorvcl oi 2C0 loot obovo

GOO toot; lor upward loads on olhor slopoa. and downward loada on all alopoo, corroapondhi^ ioada a:o in jirofortlon !o those tor upward load

for 0* lo 20* olop-i.

NIST NCSTAR 1-1B, WTC Investigation 235
Annex B3

-1

This page intentionally left blank.

236 • NiST NCSTAR 1-1 B,WTC Investigation
Annex B4

Tables in 1967 Chicago Municipal Code

B4.1 EXHIBITS

TABLE 68-4.1. MINIMUM DESIGN' WIND PRESSURES FOR

BUILDINGS AND OTHER STRUCTURES.

Height Zone fleet) Wind Pressure

(lbs. per sq. ft.

Buildings Less than 300 Above 300

20 Add 0.025 !b. per foot for each

foot above 300

Towers. Tanks

and Chimneys

Less than

200 Above 20020 Add 0.025 ib. per foot for each

foot over 200

Solid Signs Less than 100 Above 100

30 Add 0.025 !b. per foot for each

foot above 100 Open Signs For all heiphts Increase wind pressure established for soiid signs by 1/3

TABLE 70-2.4 (a). BEARING VALUES OF SOILS

Maximum

Preaaun Pounda

Type of Soil per Squart Foot

Sand—compftct and clean _ 5.000 S&ad—silty and compact Z.OOO Inorganic silt—compact 2,500 aay—very eoft 500 CTay—Boft „ 1.500. Clay—stiff 2.500 Clay—tough „ „ 3.500 Clay—ver>- tough 4.600 Clay—hard 6,000 Gravel _ - 6,000 H&rdpan _ 12,000

Solid rock 200,000 Organic BOil 0 KUed ground or loam 600

NISTNCSTAR 1-1B, WTC Investigation 237
Annex B4

TABLE 72-2 (A). MAXIMUM ALLOWABLE UNIT STRESSES

(POUNDS PER SQUARE INCH)

iib«r fttfMS Species and tantion Compraaston and parallttl \o Horizontal Compr««!non parall*i lo Modului of ~omm*rciQl groin Shear acrosi 9rain Da»tlclly Grade (ii.) ()c) E Cypress 1300 120 300 900

Douglas Fir 1300 100 325 1200 1,600,000 Plywood (Fir)

Built up Section 1500 100

35* 400 1500 1,600,000

Laminated

Timber 1100 75 400 1500 1.600,000 Hemlock 1000 90 350 1100 1.400,000 Oak 1300 120 600 1000 1.500,000 Redwood 1100 75 300 1000 1,200.000 Southern Pine

Longleaf 1300 120 450 1000 1,600,0(K) Shortleaf 1100 120 400 900 1,6(K},0(M)

Spruce

Sitka or Eastern 1000 75 300

"Shear in plane of piles. "For L/D of 800 1,200,000

nieveo or leu,

238 NISTNCSTAR 1-1 B, WTC Investigation
Annex B5

Tables in 1965 BOCA Basic Building Code

B5.1 EXHIBITS

Tails 15.—Mrnnrru UffuoiLMXY Distubutxo Livx Loahs

Alley*, ctrtvewajri, ynrds »nd terraces Pedeatnaa

Vehicular Armortcs and drill roonu Atacmblr

Filed seal* Removable or no testi Balcony (exterior) UowliRg alleyi. pool rooms ftod siiniUr rccreatiotiAl areis Otss Rooms

Fixed sexti > Removable scats •Cornices ....*... Corridors : Hotels, hospitals and mulit-fareity dwelltora One- and Iwo lamily dweUinrs

Servinf public rooms in hotria Corridors and entrance hallways other thao residential building

Corridors (other tfau those spcci&catly designated)

Private Public Court rooms Dance halts and nrnrnasiums

DwclliDfs

Dwellinr units (Multi-family dwellings)

First Aoor , Second Hoor and habitable attic Uninhabttsble attics Elevator machine rooms Caraf CI and itables, passenger cars not exceeding, 4.000 lbs. wt. Garages, buses and trucks not exceeding 20,000 lbs. wt. : (b) Columns, beams and girders Floor slabs Granditands. reviewing stands and bleachers

Hospitals -. Operating rooms

Private rooms Wards

Libraries : Reading rooms

Stack rooms

Loft buildings and light manufacluring Manufacturing

Heavy

Lifht (See Loft buildings. . . ) Marquees

Ufficc buildings: Lobbies Rooms

P«nal iniiiiuiinns : cell blocks Parking structures, passenger cars only:

Parii of Aoor accessible lo wheel loads Parts of Hoor not accessible to wheel loads Restauranis and public dmins rooms

Reviewing stands and bleachers (See Crandilandi . . . ) Sidewalk*

Skating rinks

Stairi. ftre escapes and eaitways

Storage warehouse: Heavy

Light

Stores and «hops

Retail, and banking rooms

Grade Hoor Upper rioors Wholesale

Theatres : Aisles, corridors and lobbies Patconics Orchestra tloor^ Stage rioors

Pounds per square foot

too 250

I JO

<S0 100

100

7560

60

lOO

7560

40 lOO

100 Same as occu- pancy served. 100

100

10040

40

30

20(c)

100

75

120

175 10060

40

40

60 t50U>

125 Sat lets than

artuat Inads. 75

!005040

75

50

iOO 35075

100 250

125

100

75 US

1006060

ISO

Vote a. .Minimum ISO Ib./^q. ft hut not les* than actual wn^hi of Joatlci -helves. Noic b. Fur irarjKes for Thicle^ rKcretluiK JO, 000 IbH. wi.: :iee ^ec. TO? Note c. Live load need l>e applied to joists or lo hniium uhords 'tf irui^et *ff iriitveU raiurs only in iho*e portioni of ^ittc ipacc having a clear iteight of lorty two (42) tnchcs '»r mwr brtwern joi*! rafter tn conventional rafter construction; and hetween Irattom chord and any other member in trussed

itr trussed rafter conitruction. However, lu»^ts or the I'Ottom chords or irufisen t»r trui^^ed rafters <h>n be designed to «uiiain ihe imposed dead load or ten pounds per square foot (tO p.s.i ), whichever be greater, uoiformly tliitnbuted over the emire span.

NISTNCSTAR 1-1 B, WTC Investigation 239
Annex B5

Tablb 14.—CoNCEN'niATED Loads

LocsiioB

Elevator reacliine room grtlinf (on trtA of 4 »4. in.) Finiili iigbt fioor plate ccmMru<(ion (on area a( 1 sq, in.) Cuace*. ptcaaart c&n

Garaica. iruckt (not ieu Umn ) SO ptr cent tnaxtmum wHtt! load)

Office floori Scuttle* and akyligbt rib« Siilewaika

Stair trtada (on centtr of tre»d) ,

Pous4a

300 200 2000

2000 200

8000

300

Exhibit B5-1 External Wind Pressure on Roofs

ExTEjtNAt Wind Prisscre on Roops

Raiin of Side- wall HeiKht to Duildinif Width

VVinclwar<i Slope of Koofs

Flat Roofs Lesi than

!:12

1 : 12 to 4.05:12

•i.0S:!2

to 6:12

6:12 to 12:12

Leewarrl Slooe

All Slopea

0.3 ~.W —.60 —.06 .12 .19 —.SO

0.4 —.60 —.60 —.3} .01 .09 —.SO

0.6 —.60 —.60 —.49 —.20 —.06 —.so

C.8 —.60 —.60 —.S7 —.30 —.18 —.50

t.O or more —.60 —.60 —.60 —.39 —.28 — SO For all roof iiiriaces having a slope greater than 12:12 ilie same wintl forces as for vertical surfaces shall be assumed.

Table 15.—Prz-su mstac SusfAcs Beahinc Values of Foc.vdation .VIatoijals

CI««i oi rnatcrial iOnt per square f(50«

1 —Ma«»ive cryttalline bed rock mduiJing jrajiitt. liionie. gneuJ,

irap rock, hard iimealone and Joiotnile 3—Poliiied rock including be<idt<l iimeslone, scbitt anil tiate m

•ound condition

i—SedimcTiLary rock including bard abalea, landitonea, and tboroui,!)'y cementetl conglomerate*

*—Soft or broken bed rock (tjtcluding ibale). and toil hmeilonc . 5~—Compacted, partialis ceiaented graveia, iutd sand hardpan

<»verlyifig rock ... . . , 6—Gravel and aajid-gravel raixturei

7 —Lixiie gravel, hard dry clay, compact coarje «and. and »oft ihairi fr— Looac, coaric <and and a^nd gravcJ miilurca and compact ^Re

• and (confinetl) 9— Looae mediiUB aand (coeiftnexj), aliff clay 10—Soft broken abate, »o(t clay

100

*0

2510

10

64

33l.J

240 NISTNCSTAR 1-1 B, WTC Investigation