WTC Building 7

Ulf schrieb:Wo soll denn die Hitze für dieses einmalige Phänomen hergekommen sein?

voidol schrieb:Und zum Erweichen von Stahl braucht es keine sonderliche Hitze.

Ulf schrieb:Brandschutz

NIST did have some “preliminary hypotheses” on 7 WTC, Dr. Sunder said. “We are studying the horizontal movement east to west, internal to the structure, on the fifth to seventh floors.”
Then Dr. Sunder paused. “But truthfully, I don’t really know. We’ve had trouble getting a handle on building No. 7.”

@Ulf schrieb:
Wo soll denn die Hitze für dieses einmalige Phänomen hergekommen sein?

NIST admitted in their December 2007 advisory committee meeting that the fuel load could only support 20 minutes of fire in any given location.
"Question: …fire moved every 20 minutes; essentially it started and stopped every 20 minutes, so if
you do not have fuel in WTC 7, how could fires burn for as long as they had and taken out this major structure that had good fireproofing?"
"Answer (Sunder): The fires moved from location to location, meaning that at any given location the
combustibles needed about 20 minutes to be consumed. While the combustibles at a location were
being consumed, the fire front would be progressing to adjacent combustibles."

Q: There was a previous mention of the day tanks and pressurized lines for diesel fuel in WTC 7. A 4 lb/ft2 fuel load fire moved every 20 minutes; essentially it started and stopped every 20 minutes, so if you do not have fuel in WTC 7, how could fires burn for as long as they had and taken out this major structure that had good fireproofing?

A: The fires in the towers did not stop after 20 minutes. The fires moved from location to location, meaning that at any given location the combustibles needed about 20 minutes to be consumed. While the combustibles at a location were being consumed, the fire front would be progressing to adjacent combustibles. Also, recall that the 4 lb/ft2 is the fuel load that is actually consumed. The total loading of furnishings could have been higher if there were substantial numbers of file cabinets, etc. Furthermore, the jet fuel led to widespread ignition of the combustibles, but the jet fuel was consumed quickly and was a minimal contributor to the sustained fires that weakened the structures in WTC 1 and WTC 2.

In the case of WTC 7, the estimated combusted fuel load was similar to the 4 lb/ft2 estimated in the towers. The initial fires were small enough that most were not visible at the windows for several hours. Most likely, these early fires involved only a small number of workstations at a time. The early fires raised the air temperatures, preheating other clusters of cubicles and leading to the larger fires seen during the afternoon.

Once the fires had begun heating the air, the overall air temperatures on a floor continued to rise as new combustible material became involved. The local air temperatures began to fall when the local fuel supply was depleted and fresh air reached that area. The heating of the structure through its protective insulation was a result of both the high air temperatures that were reached and the duration of those high air temperatures, not just the duration of local burning.

Q: Why would these fires have burned for as long as they did? If beams sagged, buckled, and pulled they had to be exposed to the fire for more than 20 minutes.

A: The critical issue is the combination of temperatures to which the beams are exposed and the duration of that exposure. The FSI calculations showed that the floor assemblies were sensitive to these exposures, reaching 500 °C to 600 °C in some regions. While the metal decking had insulation on its lower surface, the concrete floor slabs had no fireproofing on their top surfaces. The floor beams were slender elements and had low thermal mass, and the thickness of the thermal insulation on the floor beams was less than that on the girders and columns. The sensitivity to heat was compounded by the very large spans. In the northeast section of the building there were 2000 ft2 large span floor areas. Our analysis indicates fairly large magnitudes of sag in these areas.

woogli schrieb:Hier ist ist alles im Zusammenhang:

Ulf schrieb:Ach woogli. Hab doch zitiert aus einem Zitat, wo nur stand, was ich zitiert.

@Ulf schrieb:
Hab doch zitiert aus einem Zitat, wo nur stand, was ich zitiert.

woogli schrieb:Dann recherchiere bevor du auch nur ein Wort aus VT Quellen zitierst!

Ulf schrieb:Ich hoffe, das tust du auch bei den offiziellen Quellen so, bevor du diese zur Wahrheit erklärst.

Marina1984 schrieb:Wenn mir GARKEINER eine plausible erklärung geben kann, dannsollen ALLE davon ausgehen, dass dies alles vom US-Regierung oder was sich dahinterverbirgt gemacht wurde.

Das glaube ich nicht.

@Ulf schrieb:
Der Nist-Report ist zweifelhaft.

@Ulf schrieb:
Um Träger zu Fall zu bringen müssen nun mal Voraussetzungen geschaffen sein. Nist hatte damit offensichtlich große Probleme, zu erklären, wie diese Voraussetzungen zustande gekommen sind.

Ulf schrieb:Der Nist-Report ist zweifelhaft

woogli schrieb:The FSI calculations showed that the floor assemblies were sensitive to these exposures, reaching 500 °C to 600 °C in some regions.

Ulf schrieb:Da werden Zahlen genommen, die jeder Grundlage entbehren, nur damit es passt.
Wie soll es zu dieser Erhitzung gekommen sein? Und das stundenlang.

OpenEyes schrieb: Du behauptest, also trittst Du den Beweis an