University of Alaska Building 7 Report

The loading condition for the Floor 12 and 13 assembly was calculated by imposing axial forces acting on the top of Floor 13. The column number sequence is shown in Figure 2.24 (NIST, 2008, NCSTAR 1A). The axial force acting on each column is given in Table 2.1. The loading for Column 79 is highlighted in the table because NIST concluded that the collapse of Column 79 at Floor 13 initiated the building’s progressive collapse (NIST, 2008, NCSTAR 1A).

University of Alaska Building 7 Report

Articles inside

REFERENCES

Figure 4.20 Velocity comparison between Chandler measurement (green plotted line) and UAF simulation (red plotted line). Bold green trend line illustrates free fall

Figure 4.17 (a) Comparison of simulated collapse to perspective 1; (b) comparison of simulated collapse to perspective 2

2.7 Summary and Conclusion

3.2.2 Girder A2001 Web Stiffeners Prevent Flange Failure and Girder Walk-off

Table 2.3 Comparison of UAF and NIST Modeling

4.6 Results of Core Column/Exterior Column Failure Analysis

2.6.2 ABAQUS Analysis

3.2.3 Lateral Support Beams Prevent Beam Buckling

2.6.1 SAP2000 Thermal Deformation Analysis

Figure 2.36 Modeling process for a beam to girder shear connector, “STC.”

Table 2.1 Column loading for the Floor 12 and 13 assembly

Figure 2.21 SAP2000 model of entire WTC 7 without roof

Figure 2.24 Column number layout of Floor 13 (NIST, 2008, NCSTAR 1A

Figure 2.26 Small section of typical floor slab of WTC 7 with finer meshing

Figure 2.29 Plan View: Model of floor slabs in strong direction (parallel to flutes

Figure 2.46 Seated moment connection of exterior girders to exterior columns ABAQUS model

2.2 Solid Works Modeling

2.1.3 Background Studies

1.5.3 Approach 3: Simulating the Collapse of WTC 7

Figure 2.5 Area of floor where connection failure was modeled by NIST

1.5.2 Approach 2: Evaluation of NIST’s Collapse Initiation Hypothesis

Figure 2.6 Progressive collapse separated into two parts

Figure 2.3 Approach used to model buckled beams in LS-DYNA model (NIST, 2008, NCSTAR 1-9, Vol. 2

1.4.3 Arup and Nordenson, April 2010

Figure E.3 Finite Element Model of WTC7 in SAP2000, as viewed from the south

Figure 1.6 WTC 7 was in free fall for approximately 2.25 seconds over a distance of approximately 8 stories or 32.0 meters (NIST, 2008, NCSTAR 1A

EXECUTIVE SUMMARY

2.2 Hypothetical Failure Mechanisms for West Penthouse and North Face Roofline

Figure 1.4 WTC 7 tenants on September 11, 2001 (FEMA, 2002

Figure 1.9 WTC 7 steel frame building geometry prior to its collapse (FEMA, 2002

Figure 1.5 The collapse of WTC 7 at 5:20 PM (source unknown

1.4.2 National Institute of Standards and Technology, November 2008