Welcome benthamitemetric - thanks for the list of links.
https://www.metabunk.org/members/benthamitemetric.6172/
@J Orling.
Sander check out the witness testimonies referenced by benthaqmitemetric - follow the link and read this testimony:
Supplemental and Amended Second Declaration of Joseph P. Colaco
HINT:
...he is a man after your own heart.
I skimmed through a few bits there and some of them below align wih my suspicions
Jose L. Torero pretty much states my suspicion of TTF.
"Based on my work to date, including computer modeling performed by me and my staff at the University of Edinburgh, it is my opinion that a diesel fuel fire occurred on September 11, 2001 on the fifth floor of WTC7 in the area of the transfer trusses. Such fires, fueled by between 7,350 and 9,300 gallons of diesel fuel from a leak in the Salomon Brothers’ Standby Generator System, would have been of such high temperatures and lasted for such duration that they would have compromised the strength of the transfer trusses, caused their failure, and ultimately caused the failures of Columns 79 and/or 80 leading to a global collapse of WTC7.
Specifically, a diesel fuel fire in the fifth floor mechanical room would heat: (1) the members of Truss 2 that are fully immersed in the mechanical room, including Columns 77, 80, and the eastern diagonal of Truss 2; and (2) the members of Truss 1 immersed in the north wall of the mechanical room, though to a somewhat lesser degree.
The diesel fuel fire would have generated sufficiently high structural temperatures in the members of Truss 2 to cause them to lose strength and fail.
This failure of the eastern side of Truss 2 would have caused load redistribution towards Truss 1 and Column 79, which would overload these members. The east diagonal of Truss I, which had the lowest factor of safety, would have likely failed first and resulted in the subsequent failure of Column 79. This was manifested visibly as the sinking of the East Penthouse.
The combined effect of the failure of the eastern side of Truss 2, Column 79 and the east diagonal of Truss 1, would have resulted in significant load transfer to Columns 73 and 74, as well as the core. This was manifested visibly as the “kink”. As Columns 73 and 74 were not immersed in the mechanical room, and therefore not significantly heated, a delay was observed between the sinking of the penthouse and the subsequent “kink”.
As described in the Second Declaration of Guy Nordenson, loss of the eastern region of the building’s interior created a large area of laterally unbraced perimeter frame and activated the fracturing of the floor slabs at the western trench headers leading to global collapse."
and Guy Nordensen (who I worked with on a project briefly) said:
"Disproportionate collapse of the building interior spread westward due to failure of the transfer trusses and then to the exterior because the cantilevered transfer girders on the north face were supported by one of the transfer trusses. The stacking of critical structural transfer elements created interdependence such that the loss of the transfer truss caused: (1) the cantilevered transfer girders to fail; (2) the perimeter frame to redistribute load and buckle in the unbraced lower northeast comer of the building, and (3) formation of the “kink” in the north facade visible in the video footage.
Whether the failure of Columns 79 and/or 80 was initiated by a diesel fuel fire on the fifth floor or an office contents fire between the ninth and thirteenth floors, the horizontal progression and global collapse ensued as a result of one or more of the following omissions: (1) girder to column connections that are weak in tension and did not brace the columns in accordance with the NYCBC requirement that the bracing be able to support 2% of the design vertical load carried by the column; (2) inadequate redundancy in the configuration of the transfer structures; or (3) lack of structural integrity (resistance to disproportionate collapse) in the design and construction of WTC7, including, without limitation, disregard for floor segmentation caused by the trench headers.1L"
and this from Frederick W. Mowrer:
"After 3:30 PM, photographic evidence shows fires and smoke consistent with a petroleum-based diesel fuel fire emanating from the vicinity of the fifth/sixth floor louvers on the east side of WTC7. One such photograph is attached hereto as Exhibit B. Four of the nine generators comprising the Salomon Brothers’ Standby Generator System were located in the northeast corner of the fifth floor.
The Standby Generator System installed by Solomon Brothers on the fifth floor of WTC7 constituted an electric power generating plant under Sections 27-250 and Reference Standard RS 3-3 of the NYC Building Code. As such, the area surrounding the generators and associated fuel piping required a higher fire resistance rating than the rest of the building. Sections 27-239 and 27-240 of NYC Building Code required that spaces having a higher fire index than the rest of the building be separated from adjoining spaces both vertically and horizontally by fire divisions having at least the fire resistance rating specified in Table 5-2 of NYC Building Code.
WTC7 was generally classified as a Group E occupancy. As an electric power generating plant, the Salomon Brothers’ Standby Generator System was classified as Group D-I occupancy under RS 3-3, thus mandating 3-hour fire resistive separation construction. Absence of such 3-hour fire resistive separation of the generator spaces on the fifth floor of WTC7 made it non-compliant with the NYC Building Code."
and this:
However, if you read chapter 4 of the report, you'll find that the buckling of the exterior columns at the lower floors was the first part of the global collapse, but that this was only the last stage of the failure. When column 79 failed (and redistributed forces causing columns 76-78, 80 and 81 to fail as well), large sections of the interior of the building failed and collapsed, but they pulled inward and away from the exterior facade of the building.
This is why in videos, you can see the penthouse collapse well before the building as a whole goes down - the penthouse shows what's going on inside the building.
"During the period of global collapse, there were 2.25 s of approximate free-fall because the structure of the building had already collapsed enough to allow that. What was falling was the facade, and what remained of the other floors. Stage (1) of the global collapse (buckling of exterior columns on lower floors) occurred because the interior columns had already failed; the facade and remains of the floors was essentially unsupported at this point, which was why they were able to collapse so quickly (for about 2.25 s, which was around a third of the total collapse time), which would be until they hit the debris and remaining structure in the lower floors."