




























































































Study with the several resources on Docsity
Earn points by helping other students or get them with a premium plan
Prepare for your exams
Study with the several resources on Docsity
Earn points to download
Earn points by helping other students or get them with a premium plan
Community
Ask the community for help and clear up your study doubts
Discover the best universities in your country according to Docsity users
Free resources
Download our free guides on studying techniques, anxiety management strategies, and thesis advice from Docsity tutors
modulus was measured on the WTC steels summarized in Table 2-1. Solid line is. Eq. 2-2. Shear modulus, G, calculated from and v via Eq. 2-4.
Typology: Slides
1 / 324
This page cannot be seen from the preview
Don't miss anything!
Christopher N. McCowan Stephen W. Banovic^ Richard J. Fields
Thomas A. Siewert
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
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
buildings. In addition, NIST could not verify the interpretations of codes used by applicable authorities in determining
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
Use in Legal Proceedings
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 1-3D
CODEN: NSPUE
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- Mail: Stop SSOP, Washington, DC 20402-
Abstract
elastic, room-temperature tensile, room-temperature high strain rate, (^) impact, and elevated-temperature
to 900 °C. The expression for E{T) for T < 723 °C is based on measurements of WTC perimeter column steels. Behavior for T > 723 °C is estimated from literature data. Room temperature tensile properties
impact toughness at room temperature of nearly all WTC steels tested exceeded 15 ft lbf at room
structural steels from the literature. The measured elevated-temperature stress-strain behavior of WTC
complete constitutive law for creep deformation based on experimental measurements. For the steels not
NISTNCSTAR 1-3D, WTC Investigation ill
Table of Contents
Abstract (^) iii List of Figures (^) ix
Preface (^) xix
Executive (^) Summary xxxi
Chapter 1
1.1.1 Elastic Properties (Chapter (^) 2) 1
Chapter 2
2.1 Introduction 1
1
2.2 Experimental Procedure 11
1
2.4 Elastic Properties (E, v, G) for T>910 °C 13 2.5 Elastic Properties (^) (E, v, (^) G) for 723 °C<T<910 °C 13 2.6 Uncertainties 14 2.7 (^) References 14
NIST NCSTAR (^) 1-3D. WTC Investigation v
Table of Contents
6.3.1 Tensile Tests 130 6.3.2 Creep Tests 130 6.4 Recommended values for steels 134 6.4. 1 A Universal Curve for Elevated-Temperature Tensile Properties 1 34 6.4.2 Analysis of Tensile Data 136 6.4.3 Estimating Elevated-Temperature Stress-Strain Curves 137
6.4.5 Recommended Values for Bolts 155 6.5 Summary 157 6.6 References^158
Chapter? Summary and Findings 161 7.1 Summary 161 7.2 Findings 162
Appendix A Data Tables and Supplemental Figures 163
Effects of Deformation of Wide-Flange Core Columns on Measured Yield Strength 253
Provisional Analysis of High-Rate (^) Data 263
Deformation of Steels Used in WTC 7 273
Appendix E Specimen Geometry Effects on High-Rate Tensile Properties (^279)
vni NIST^ NCSTAR^ 1-3D,^ 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 2-2.^ Young's modulus, EiT). and shear modulus, G(T) for 0°C <^ T< 725°C. Young's modulus was measured on the WTC steels summarized in Table 2-1. Solid line is
polynomial (Eq. 2-3) for 0 °C <^ r< 725 °C 16
Figure 3-1. Flat tensile specimen typically used for standard room-temperature quasi-static tensile tests 21
1
Figure 3-3. Flat tensile specimen used for room and elevated-temperamre tensile tests 22 Figure 3^. Flat tensile test specimen used for some creep tests 22
tests ; 23
the specimen portion that is in tension 25 Figure 3-10. Heat affected zone tensile specimen with weld and web machined flush^ to^ the^ flange
NISTNCSTAR 1-3D, WTC Investigation ix
List of Figures
Figure 4-6.^ Examples of tensile high-rate stress-strain curves for F, =^50 ksi perimeter column steel M26-C1B1-RP (^) ; 87
Figure 4-9.^ Strain^ rate^ sensitivity^ of yield and tensile strength as a function of specified minimum yield strength (^92)
on the A 325 bolt 94 Figure 4-12. Comparison of strain rate sensitivities of NIST WTC steels to values for structural
Figure 5-1^. An^ example^ transition^ curve^118
direction 118
adjacent HAZ of perimeter column N8-C1M1, the flange and adjacent HAZ of perimeter column C 1 0-C 1 M 1 119
perimeter column N8 and the web of wide-flange core column C-80 120 Figure 5-5.^ Transverse Charpy impact data from samples from perimeter column truss seats^ M4,
Figure 5-6.^ Longitudinal Charpy impact data for A 325 bolts 122 Figure 5-7. Summary plot of the dependence of absorbed energy on test temperature for all
(10 mm^ by^10 mm)^ specimens^123 Figure 5-8.^ Summary plot of the dependence of absorbed energy on test temperature for all truss
(10 mm by 10 mm) specimens 124 Figure 5-9.^ Strength-toughness relationships for several types of structural steels^ from^ the^ WTC construction era, after Irvine (^) (1969) 125
longitudinal (^) specimen orientation from an N8-C1M1 perimeter column (WTC 1-142-
NISTNCSTAR (^) 1-3D, WTC Investigation xi
List of Figures
Figure 5-11.^ Scanning electron micrographs of the fracture surface of an N8-C1M1 perimeter
Figure 5-12.^ Perspective view of the fracture surface of sample N8-C1M1 showing the long peak- valley features characteristic of the fracture surface for transversely oriented impact
Figure 5-13. A gray-scale image (a) and compositional maps from fracture surface of an N8- ClMl perimeter column Charpy V-notch specimen. The relative concentrations of
Figure 5-14. The fracture surface of a perimeter truss seat, N13-C3B1 that was tested at room temperature shows cleavage facets, which indicate a brittle fracture mode 127
Figure 6-1. Elevated-temperature stress-strain curves. Specimen N8-C1B1 A-FL is from a Fy 60 ksi perimeter column flange plate from WTC 1 column 142 between floors
Figure 6-2. Creep curves of A 242 truss steel from specimen C-132 at 650 °C. Dashed lines
Experimental curves are graphically truncated at e =^ 0.05 132 Figure 6-3. Creep curves of A 242 truss steel from specimen C-132 at 600 °C. Dashed lines
Experimental curves are graphically truncated at s =^ 0.05 132 Figure 6-4.^ Creep curves of A 242 truss steel from specimen C-132 at 500 °C. Dashed lines
Experimental curves are graphically truncated at e =^ 0.05 133 Figure 6-5.^ Creep curves of A 242 truss steel from specimen C-132 at 400 °C. Solid lines
the parameters in Eqs. 6-16, 6-17, and 6-18.^ Experimental curves are graphically
individual tests are normalized to the mean room temperature yield strength. The
individual tests are normalized to the mean room temperature yield strength. The
Figure 6-8.^ K(T), Eq. 6-5,^ for the A 36 steel of Harmathy (1970), used to model the behavior of
Figure 6-9. n(T), 6-6, for the A 36 steel of Harmathy (1970) used to model the behavior of steel with =36ksi 140
xii NIST^ NCSTAR^1 -3D,^ WTC^ Investigation
List of Figures
This page (^) intentionally left blank.
xiv (^) NISTNCSTAR (^) 1-3D, WTC (^) Investigation
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
specimens (^10) Table 1-3. Mechanical testing definitions used in this report 10
1
Table 3-3. Results of transverse tensile tests on welds from specimen N-8 (WTC 1, column 142, floors 97-100, specified F, =^60 ksi) 32
Table 3-5. Summary of mechanical properties and chemical compositions for steels from
Table 3-6. Summary of mechanical properties and chemical compositions for steels from high-
Table 3-7. Summary of mechanical properties, chemical compositions, and relevant ASTM and
Table 3-8.^ Summary of mechanical^ properties^ and^ chemical^ compositions^ for^ steels^ from^ core
Table 3-9.^ Summary of mechanical properties and chemical compositions for steels from core box
Table 3-10. Common truss component dimensions and standards 57 Table 3-11.^ Summary of mechanical properties and chemical compositions,^ and^ specifications for truss steels tested 58 Table 3-12. Summary of mechanical properties, chemical compositions for truss seat steels tested 61 Table 3-13.^ Estimated static yield strengths and work-hardening^ parameters, Eq. 3-5,^ for^ perimeter
and truss steels 68
NIST NCSTAR 1-3D. WTC Investigation xv
List of Acronyms and Abbreviations
Acronyms
AISC American^ Institute^ of^ Steel^ Construction
ASTM ASTM International AWS American Welding^ Society BPS Building Performance Study CVN Charpy V-notch FATT fracture appearance^ transition^ temperature FEMA Federal Emergency Management^ Agency HAZ heat-affected zone HSR high-rate style HSLA high-strength, low-alloy JIS Japan Industrial Standard LERA Leslie E. Robertson Associates LRFD load and resistance^ factor^ design METT mid-energy transition^ temperature NIST National Institute^ of^ Standards^ and^ Technology PANYNJ Port^ Authority^ of^ New^ York^ and^ New^ Jersey PC&F Pacific Car^ and^ Foundry PONYA Port^ of^ New^ York^ Authority SEAoNY Structural^ Engineers^ Association^ of^ New^ York SHCR Skilling, Helle,^ Christiansen,^ &^ Robertson SMA shielded metal^ arc SRS strain^ rate^ sensitivity use United States^ Code WF wide-flange (a^ type^ of^ structural^ steel^ shape^ now^ usually^ called^ a^ W-shape) WTC World^ Trade^ Center WTC 1 World Trade Center^1 (North^ Tower) WTC 2 World Trade Center^2 (South^ Tower)
NISTNCSTAR 1-3D. WTC Investigation XVll
List of Acronyms^ and Abbreviations
WTC7 World Trade Center 7
°F degrees^ Fahrenheit
ft foot
gal gallon GPa gigapascal;^ 1x10^^ N/m"
in. inch L liter
m meter
mm millimeter Mn magnesium
MPa megapascal; 1x10^ s second
xvni NISTNCSTAR 1-3D, WTC Investigation