REVIEW OF COLLAPSE FEATURES OF WTC1, WTC2, AND WTC7 WITH FOCUS ON THE QUALITIES OF CONFINEMENT AND REGULATION
5.1: THE CASE OF WTC1
Please recall the order of events leading up to and during the WTC1 collapse sequence from section 2.4:
1) Deformations: Inward bowing of the south face
2) Earliest detectable creep movement of the antenna and northwest corner
3) Appearance of ~87th fl S face ejections
4) Appearance of 95th fl W face ejection
5) Visible downward movement begins: Concave deformation of the roofline, antenna drops before north or west perimeter walls
6) Columns fail over tilt of less than 1 degree, appearance of 98th fl ejections and 105th floor ejections
7) Appearance of 77th fl W face ejections
8 ) Splitting of all perimeter walls: All visible upper parts fall out and over lower parts
9 ) Southward sliding of upper portion
10 ) Dis-integration of upper portion
What people see as the beginning of visible downward movement is marked blue.
The ejections marked red emerge before visible downward movement begins.
At higher elevations in each building the core columns segments were connected by using bolts and plates only with no welds. This information was very difficult to find. The core column-to-column connections were not staggered as they were along the perimeter. All 47 core columns had bolted column-to-column connections at the exact same elevation separated by 3 floors on floors 86, 89, 92, 95, 98, 102, 105. Detailed information on the connections is available at this link.
As shown in section 2.3, the NIST claimed numerous times within their reports that the first signs of failure of WTC1 was along the 98th floor and the building tilted 8 degrees to the south as columns progressively failed from south to north. In reality, the visual record shows the first ejections came from the south face around floor 87 and from the west face along floor 95.
The appearance of the 95th floor ejections is marked by a green line at the beginning of the graph. The ejections occur well before downward movement of the antenna, northwest corner, or the fire on the upper southwest corner of the building.
The next short video clip demonstrates beyond doubt that overpressurizations from the 95th floor and the 92nd floor emerge before those along the 98th floor and before visible downward movement of the building. It is taken from the larger clip linked in phenomenon #3:
Only after the emergence of the 87th floor south face ejections and the 95th and 92nd floor west face ejections does visible downward movement of the building begin.
Neither of these ejections were mentioned within the NIST report
5) VISIBLE DOWNWARD MOVEMENT BEGINS: COLUMNS FAIL OVER TILT OF LESS THAN 1 DEGREE, APPEARANCE OF 98TH FLOOR EJECTIONS AND 105TH FLOOR EJECTIONS
The columns fail from south to north and from east to west so the clearly visible NW corner would be the last columns to fail. The moment of failure is shown:
By synchronizing the video from the northeast, north, northwest and west views, one can determine the moment the northwest corner fails by visual inspection. It can be easily verified that the northwest corner had already failed in the frames shown below:
A more precise determination of tilt angle:
Any capable person can determine tilt angles from various perspectives over which all columns fail by using a simple 4 step process:
A) Verify the west face fails from south to north:
B) Verify the north face fails from east to west:
C) Determine precise moment of failure of the northwest corner:
D) Measure tilt of antenna and other normally vertical features of the deforming structure from multiple angles at that moment
Steps 1 and 2 allow one to verify that the northwest corner is the last set of columns to fail. The precise moment of failure of the northwest corner can be determined by using the high resolution Sauret video and tracking the movement of the northwest corner:
The velocity curve in black allows the determination of the moment of failure of the NW corner with remarkable precision. One would naturally look at the point in which the velocity makes the initial sharp, downward transition. Both visual inspection and object tracking allow anyone to spot the moments of failure of the NW corner.
By synchronizing videos from other perspectives with the Sauret video from the north, tilt angles can be determined from each perspective.
Tilt angle over the initial column failure shown as a 3 image gif here
which represents 0:21 in the synchronized video:
These two images show the true state of tilt just after the moment that the last columns failed on the NW corner of the building. In the lower picture the NW corner has already failed at fl 98. The break on the corner is already visible so this image is a conservative estimate of true tilt. Precise measurements actually yield less tilt than is shown in the images. More precise measurements are available here:
Evolution of angular movement from NE viewpoint visualized (angle exaggerated)
Between frames 165 and 217, the antenna tilted faster and reached about 0.75°. After frame 217, the tilting of the antenna stopped increasing for the next 40 frames. During that time the antenna merely shifted southward while the north face (upper floors) apparently tilted a bit more.
In the GIF above the x component of the movement is extremely stretched. Both axis are numbered each in 10000 units. A thin blue line shows the position 10 frames in the future and a thin yellow line shows the position 10 frames in the past. The thin horizontal green lines show the measured antenna section. The vertical lines are extended to see at which elevation the "antenna" collectively pivots (floor 98 is about at y=70000). It is obvious that the antenna started to descend at virtually 0° tilting. At about 0.6° tilting the north face gave way and stopped tilting further for the next 40 frames.
The same motion seen from the west:
Within these observations are multiple indications of collective core failure. Not one of these observations is recognized within the NIST reports. The author could understand that the official reports could overlook an observation or two, but consider the multiple indications of collective core failure:
Early antenna movement
Pull in of the NW corner
The upper portion of the south, west and north walls fail outside and over the lower portion
The actual measurement of tilt as the NW corner visibly fails
The upper portion detaches from the lower portion and slides southward at less than 1 degree tilt
Multiple indicators of the same behavior, none of which are mentioned within the NIST report.
9) DIS-INTEGRATION OF THE UPPER PORTION
Zooms of these images reveal the upper south wall and a large section of the antenna have fallen out and over the lower south wall, shown here.
Fig _ Each perimeter wall can be divided into 3 regions separated by reinforced MER spandrels. The colored sections in the graphics show portions of each wall that are trackable and identifiable. The colored portions are the areas of each wall that can be tracked and has a known path of movement.
Large sections of each perimeter wall were able to be tracked by reconstructing the collapses of each wall from the visual record.
Fig _ The collapse progression down the south region was well ahead of that of the north region. So along the west and east walls collapse progression proceeds down different regions at different rates. Image on right shows identifiable sections of the WTC1 west perimeter.
The movement of all 4 walls are mapped at these links:
The perimeter is most probably responding to partial core failure. Therefore, the actual mechanism of collapse seems to be partial core failure leading to collective core failure, while the perimeter deformations are merely the response to core failure.
Created on 09/19/2012 08:47 AM by admin
Updated on 05/15/2015 11:37 PM by admin