A structural re-evaluation of the collapse of World Trade Center 7 :
Subtitle: final report
Edition: INE Report 18.17
Publisher: Department of Civil and Environmental Engineering College of Engineering and Mines Institute of Northern Engineering University of Alaska Fairbanks Fairbanks, AK 99775 prepared for Architects & Engineers for 9/11 Truth
Published: March 2020
Place of publication: Fairbanks AK us
Language: eng
Number of pages: 125
First sentence: This report presents the findings and conclusions of a four-year study of the collapse of
World Trade Center Building 7 (WTC 7) — a 47-story building that suffered a total collapse at
5:20 PM on September 11, 2001, following the horrible events of that morning. Figure E.1
shows the layout of WTC 7 in relation to the World Trade Center complex prior to September
11, 2001
Table of contents: title: TABLE OF CONTENTS; title: ABSTRACT ................................................................................................................................... ii; title: EXTERNAL PEER REVIEWERS ............................................................................................... III; title: ACKNOWLEDGEMENTS .......................................................................................................... iii; title: DISCLAIMER ............................................................................................................................... iii; title: LIST OF FIGURES ........................................................................................................................vi; title: LIST OF TABLES ....................................................................................................................... xii; title: EXECUTIVE SUMMARY ............................................................................................................. 1; title: CHAPTER 1.0 INTRODUCTION .................................................................................................. 8; title: 1.1 Background.......................................................................................................................... 8; title: 1.2 Objective............................................................................................................................ 13; title: 1.3 Literature Review and Interpretation of Drawings ............................................................ 13; title: 1.4 Previous Studies of WTC 7’s Collapse ............................................................................. 16; title: 1.4.1 Federal Emergency Management Agency, May 2002 ........................................... 16; title: 1.4.2 National Institute of Standards and Technology, November 2008......................... 17; title: 1.4.3 Arup and Nordenson, April 2010 ........................................................................... 20; title: 1.4.4 Weidlinger, October 2010 ...................................................................................... 21; title: 1.5 The UAF Team’s Approach to Examining the Structural Response of WTC 7 ............... 21; title: 1.5.1 Approach 1: Structural Response to Fire Loading ................................................. 21; title: 1.5.2 Approach 2: Evaluation of NIST’s Collapse Initiation Hypothesis ....................... 22; title: 1.5.3 Approach 3: Simulating the Collapse of WTC 7 .................................................... 23; title: CHAPTER 2.0 STRUCTURAL RESPONSE TO FIRE LOADING ........................................... 24; title: 2.1 Process Overview .............................................................................................................. 24; title: 2.1.1 Software Tools and Uses ........................................................................................ 24; title: 2.1.2 General Outline of the Study .................................................................................. 24; title: 2.1.3 Background Studies ................................................................................................ 26; title: 2.2 Solid Works Modeling ...................................................................................................... 32; title: 2.3 Column 79 Buckling Analysis........................................................................................... 37; title: 2.4 SAP2000 Modeling ........................................................................................................... 39; title: 2.4.1 Structural Steel Framing and Bracing Models.......................................................... 39; title: 2.4.2 Floor Slab Sub-models ............................................................................................. 45; title: 2.5 ABAQUS Modeling .......................................................................................................... 49; title: 2.5.1 Floors 12 and 13 ABAQUS Model ........................................................................ 50; title: 2.5.2 Structural Steel Connections Using ABAQUS....................................................... 52; title: 2.6 WTC 7 Structural Response to Fire Loading .................................................................... 63; title: 2.6.1 SAP2000 Thermal Deformation Analysis .............................................................. 64; title: 2.6.2 ABAQUS Analysis ................................................................................................. 68; title: 2.7 Summary and Conclusion.................................................................................................. 73; title: CHAPTER 3.0 EVALUATION OF NIST’S COLLAPSE INITIATION HYPOTHESIS ........... 75; title: 3.1 Methodology and Modeling Assumptions ........................................................................ 75; title: 3.1.1 NIST’s Modeling Assumptions Used by UAF Team ............................................. 75; title: 3.2 Evaluation and Discussion of NIST’s Collapse Initiation Hypothesis .............................. 77; title: 3.2.1 Girder A2001 Trapped by Side Plate...................................................................... 77; title: 3.2.2 Girder A2001 Web Stiffeners Prevent Flange Failure and Girder Walk-off.......... 80; title: 3.2.3 Lateral Support Beams Prevent Beam Buckling .................................................... 83; title: 3.3 Evaluation of the Arup and Nordenson Collapse Initiation Hypothesis ........................... 87; title: 3.3.1 Discussion of Arup and Nordenson’s Analysis ...................................................... 87; title: 3.4 Evaluation of the Weidlinger Collapse Initiation Hypothesis ........................................... 91; title: 3.4.1 Discussion of Weidlinger’s Collapse Initiation Hypothesis ................................... 91; title: CHAPTER 4.0 SIMULATING THE COLLAPSE OF WTC 7 .................................................... 92; title: 4.1 Key Features of the Collapse ............................................................................................. 92; title: 4.1.1 Discussion of NIST’s Progressive Collapse Simulation ........................................ 92; title: 4.2 The UAF Research Team’s Approach .............................................................................. 94; title: 4.2.1 Hypothetical Failure Mechanisms for the East Penthouse Collapse ...................... 94; title: 4.2.2 Hypothetical Failure Mechanisms for West Penthouse and North Face Roofline; title: Collapse .................................................................................................................. 95; title: 4.3 Results of the East Penthouse Collapse Analyses ............................................................. 95; title: 4.4 Linear and Dynamic Analytical Methods.......................................................................... 99; title: 4.5 Results from Analysis of NIST’s Horizontal Core Column Failure Scenario .................. 99; title: 4.6 Results of Core Column/Exterior Column Failure Analysis ........................................... 105; title: 4.7 Summary and Conclusion................................................................................................ 109; title: REFERENCES ............................................................................................................................ 111