Don?t know if other engineers have chimed in yet, but I will debunk what the author claims right now.
?-- Photos showing people walking around in the hole in the North Tower where 10,000 gallons of jet fuel supposedly was burning…?
First, when were the pictures taken? Was it more than 15minutes after impact? Odds are it was. And as we all know, fire needs fuel to burn. With ample oxygen supply and an open fuel source- such as a compromised fuel tank- the fuel would have burned rather quickly, and at darn hot temps. So a picture of ppl walking around where the building collapsed proves absolutely nothing because the fuel would have been consumed within minutes after impact.
?–When the South Tower was hit, most of the North Tower’s flames had already vanished, burning for only 16 minutes, making it relatively easy to contain and control without a total collapse.?
Well, it?s nice that the author just proved my point for issue 1 above. I ask what suggests to the author that just because there was no active fire that a collapse could have been avoided. Considering the towers were designed to withstand an impact of a smaller plane with a lighter fuel supply and the low factors of safety they were likely using for such an unlikely worst case scenario load case. From the temperatures that the fuel would have burned and the force of impact, the structure at the area of impact was more likely than not incinerated. The steel would not have only been weakened by the heat (steel is tempered when heat is applied, making it less brittle, more ductile but it also reduces the tensile and compressive yield and ultimate strengths). So, even if the steel support structure somehow withstood the impact (not likely) it would have been tempered to the point that it wouldn?t even have been able to support the few floors above it- had it not melted outright. This would lead to collapse of the floors above the impact area which would have lead to the collapse of the rest of the tower through multiple modes: 1) Impact energy from the plane going to energy of deformation 2) Kinetic energy of the top floors collapsing (KE=1/2mv^2) onto the already compromised lower levels and 3) tempering of the structure below the impact area because heat has a tendency to radiate out from its source point- so the structure beneath the impact area was also weakened substantially by the intense heat of the fuel burning.
?–The fire did not grow over time, probably because it quickly ran out of fuel and was suffocating, indicating without added explosive devices the firs could have been easily controlled.?
Since when can fires not spread? Since when is it short work to control a fire that hot at that high a floor? The author makes so many presuppositions about things it makes my head hurt.
?–Even the flawed 9/11 Commission Report acknowledges that “none of the [fire] chiefs present believed that a total collapse of either tower was possible.”?
Can?t comment on fire chiefs and what they were thinking. Don?t know if this is even true, but I cannot see where any fire chief could say such things.
?-- Fire had never before caused steel-frame buildings to collapse except for the three buildings on 9/11, nor has fire collapsed any steel high rise since 9/11.?
To my knowledge no other buildings have been hit by jet liners with that much kinetic energy behind them, either. Multiple factors contributed to the WTC case- you might call it a complex stress case. The author over simplifies the case into a single stress, neglecting all other stresses. This makes for a HUGE amount of error.
?-- The fires, especially in the South Tower and WTC-7, were relatively small.?
Relatively small compared to what? On whos authority is the author making these claims?
?-- WTC-7 was unharmed by an airplane and had only minor fires on the seventh and twelfth floors of this 47-story steel building yet it collapsed in less than 10 seconds.
– WTC-5 and WTC-6 had raging fires but did not collapse despite much thinner steel beams.?
Don?t know about the accuracy of these statements, but the structural integrity is directly proportional to the heat of the fires and any vibration caused by impact and/or collapse and any other energy absorbed into the structure being converted to energy of deformation. Don?t feel like looking it up- a link to a reputable website would be nice if anyone has one- then I can study it in detail and give an informed view.
?-- It’s difficult if not impossible for hydrocarbon fires like those fed by jet fuel (kerosene) to raise the temperature of steel close to melting.?
On some other guys site he tries to explain away the heat and energy of the fire, but he gets about 1,364,000,000,000 Joules of energy, and claims that the fire could only have gotten to about 280degrees. Now, he is basing these calculations on the idea that the building was fully intact when the fire started so that every gram of material was there to absorb energy- which is patently false because a damn plane just slammed into the building. But, let?s take this likely underestimate and run with it. 280C=536F. Tempering can be achieved at temperatures as low as 300-400F. So, there is proof for tempering and structure weakening by the heat. Factor in the impact, the load and the heat, and you have more than enough to collapse a building. But like I said before, I would bet money that the temp the dude calc?d above are underestimations.
?Eagar points out the steel in the towers could have collapsed only if heated to the point where it “lost 80 percent of its strength,” or around 1,300 degrees Fahrenheit. Critics claim his theory is flawed since the fires did not appear to be intense and widespread enough to reach such high temperatures.?
This guy is running numbers on only the heat, again. Leave out a single factor and you have a completely different load case, and a completely different scenario.
?Other experts supporting the official story claim the impact of the airplanes, not the heat, weakened the entire structural system of the towers, but critics contend the beams on floors 94-98 did not appear severely weakened, much less the entire structural system.?
What critics? I want to see the numbers and the samples that they analyzed. But yet again, these guys are looking only at a single factor. Anybody w/ any kind of training knows better than that.
?“First, no steel-framed skyscraper, even engulfed in flames hour after hour, had ever collapsed before. Suddenly, three stunning collapses occur within a few city blocks on the same day, two allegedly hit by aircraft, the third not,” said Reynolds. "These extraordinary collapses after short-duration minor fires made it all the more important to preserve the evidence, mostly steel girders, to study what had happened.
“On fire intensity, consider this benchmark: A 1991 FEMA report on Philadelphia’s Meridian Plaza fire said that the fire was so energetic that ‘beams and girders sagged and twisted, but despite this extraordinary exposure, the columns continued to support their loads without obvious damage.’ Such an intense fire with consequent sagging and twisting steel beams bears no resemblance to what we observed at the WTC.”?
Again, only taking into consideration the heat. The energy of deformation from the plane is immense. Ignoring that completely changes EVERYTHING.
If anybody has exact numbers on stuff, I would be glad to run solid numbers to back everything up. but the biggest thing that gets me is how every damn “expert” oversimplifies the case and then makes concrete absolute conclusions. Unless you have EXACT data, you cant make EXACT conclusions. And even if you do, it really isnt safe because odds are you missed a few things in the analysis. That is what factors of safety in design are for - math simplifications, variations in materials and overlooked influences on the system. These guys are ingoring 2 of three factors and making absolute conclusions on the incomplete and innacurate information. Shit in = Shit out, ladies and gentlemen.