Thanks, sdw. So, now we know that there is little difference between the maximum burning temperature of gasoline and jet fuel. So on to the next....NO steel framed skyscraper ANYWHERE, has EVER collapsed due to fire - NEVER! There have been fires that burned intensely for 24 hours and the building was STILL standing!
Yeah, it's pretty friggin hot but it also is compressed in a turbine.Well, if you are going to say it, then you have to prove it if your assertion is queried. Myself, with no knowledge of the facts whatsoever, I'd wager that jet fuel burns hotter than gasoline.
But since you are the scientist here, maybe you can provide the scientific proof to your claim... complete with links to the data, please.
You build in a fire code because people have died in fires. It is supposed to allow folks to evacuate or survive until containment.Linked are the combustion temperature and the flash point of various fuels.
http://en.wikipedia.org/wiki/Flash_point
http://en.wikipedia.org/wiki/Heat_of_combustion
http://en.wikipedia.org/wiki/Jet_fuel
http://www.hyweb.de/Knowledge/w-i-energiew-eng2.html
http://www.tcforensic.com.au/docs/article10.html
3.1 STEEL
Appearance
Temperature
Yellow
320°
Brown
350°
Purple
400°
Blue
450°
* steel starts to weaken at 200°
* loses 50% of its structural strength and sags at 550°
* melt point of steel 1100°-1650°
Note that once the steel is hot enough to sag, the steel will deform and the building will collapse. Gasoline, Diesel and Jet Fuel all burn hot enough. Gas at 21,000 isn't that far from 19,300 so the actual fuel isn't important in this case.
http://www.kuleuven.ac.be/bwk/materials/Teaching/master/wg04b/l0400.htm
"Steel members will collapse in a fire when their temperature reaches a "critical" level. This critical temperature varies according to the load conditions, the cold design theory adopted and the temperature distribution across the section, which typically is in the range 500 to 900°C.
The fire resistance time is the time, in the standard ISO834 fire test, taken by the member to reach the critical temperature. This time varies according to the section size. In a building in which a natural fire occurs the heating rate is also influenced by the member location. The thicker the steel the slower is the heating rate and therefore the greater is the fire resistance time.
The heating rate is quantified by the Section Factor, known as the Am /A ratio, where Am is the perimeter of the steel member exposed to the fire, and A is the total cross-sectional area of the section. Consequently, a heavy member with a low Am /A ratio will be heated more slowly than a light member with high value of the section factor. Tables are published giving values of section factors for standard section sizes.
For a member to fulfil a given fire resistance requirement, it is necessary to ensure that the temperature developed in the member at the required fire resistance time (taking into account its Section Factor and any insulation which may be applied) is less than the critical temperature necessary to cause failure (also known as the "critical temperature").
For short periods of fire resistance (15, 30 minutes) stability may be attained by unprotected steelwork. A fire resistance time of 60 minutes may sometimes be obtained without applying fire protection by utilising the thermal and/or structural interaction between steel and concrete. For longer periods of fire resistance time, the steelwork can be protected by applying an insulating material, by using screens, or, in the case of hollow sections, by the recirculation of water. Composite steel-concrete structures can also exhibit significant fire resistance.
A brief survey of the simpler practical means of achieving structural fire resistance in steel structures is presented. It is important to recognise, however, that considerable research and development work (fuel loads based on natural fires) is being undertaken in Europe. This work aims to optimise the process of the fire resistant design of structural steelwork leading to further economies in construction."
You don't build a requirement for fire resistance into the building code unless you have suffered a collapse due to deformation of the steel structure.
SDW: Sure enough, your numbers are waaay low:Linked are the combustion temperature and the flash point of various fuels.
* steel starts to weaken at 200°
* loses 50% of its structural strength and sags at 550°
* melt point of steel 1100°-1650°
Note that once the steel is hot enough to sag, the steel will deform and the building will collapse. Gasoline, Diesel and Jet Fuel all burn hot enough. Gas at 21,000 isn't that far from 19,300 so the actual fuel isn't important in this case.
The link was immediately above the table: http://www.tcforensic.com.au/docs/article10.htmlYou build in a fire code because people have died in fires. It is supposed to allow folks to evacuate or survive until containment.
All good facts my friend but, what's it got to do with your earlier assertion that this overpass collapse is similar to the WTC 7 collapse? I think that any debate on 7's cause of collapse is rendered moot by the slip of Silverstein and now Kerry's bombshell. Besides, look at the footage, do you see major fires or damage?
Where'd the figures for steel come from? They sound really low, especially the 550. I assume that you're talking Centigrade?
Hey, a fellow sailor! I was originally a Electronic Technician, Nuclear (USN) but was pulled out of that berth to serve in government services. Probably a good thing as I was supposed to go on a fast attack sub afterwards. Later I thought about going into underwater construction / testing on oil rigs but found I really hated being underwater! My hat's off to you for being able to do that type of work, it takes a special person indeed!I'm not an engineer. However, I am a reserve naval officer (USN) with considerable experience in making large explosions and using explosives to remove unwanted structures.
What the the proponents of a controlled demolition don't address is how the necessary explosives would have been em placed.
There aren't a whole lot of dumb, living explosive experts. That's because I don't know anyone who would be willing to enter a severely damaged burning building to place explosives that get a little unstable when subjected to heat.
That is what would have had to happen.
While my work in the military and for the oil industry is mostly underwater, I would have insisted that the fires be out and the building cooled down before I would have done anything.
The job would have taken months. We would have done a lot of photo analyst and a lot of exploration with remote devices before we sent a person into the building.
That argues that the only way for explosives to be present in the building on Sept 11, 2001 is if they had been preplaced.
That flys in the face of the video record. Preplaced explosives would have predetonated in an uncontrolled manner when the observed heat was applied.
My other personal observation is that the actual results were probably more than Bin Laden expected.
If I wanted to make my point with the World Trade Center, I would have arranged for the buildings to remain standing.
Gutted, unuseable, unsafe with very large exclusion zones that rendered much of New York unsafe to live or work in. The zone of drop for uncollapsed World Trade Center Towers would have been about 20 blocks in all directions to allow for the actual shadow zone and the ejecta zone.
That's an pretty large area of the city that can't be used. Given the way the media works, it would be on TV pretty often. The economic impact would have been huge.
It would have taken about 4 years to remove the husks in a controlled and safe manner. Costs would have been over 40 Billion dollars.
When the buildings collapsed, they released huge amounts of insulation, office contents and other toxic materials in an uncontrolled manner. That would never have been allowed if the buildings hadn't collapsed. All of that material would have been removed before the buildings were demolished. New York is surrounded by very busy Airports. The demolition would not have been allowed to interfere with the operation of those airports. They don't let you do large explosions under the paths of aircraft.
About now, there would be teams of people creating very large holes in the ground and filling those holes would still be some years off. A very large part of New York would still be unuseable.
I think that is what Bin Laden was after.
Where'd you sail from?Hey, a fellow sailor! I was originally a Electronic Technician, Nuclear (USN) but was pulled out of that berth to serve in government services. Probably a good thing as I was supposed to go on a fast attack sub afterwards. Later I thought about going into underwater construction / testing on oil rigs but found I really hated being underwater! My hat's off to you for being able to do that type of work, it takes a special person indeed!
I was trying to limit my discussion to WTC 7 and not drag in 1 & 2 and that can of worms. Since it's open now and in regards to a timeline, allegedly there were a few building shutdowns prior to 9/11 including one on the preceeding weekend. Would open flame ignite something like C4?
While on the subject of those 2 buildings i would like to say that the thing that bugged me the most was the way the 34 story top part of (was is buildiing 1?) seperated and started falling at an angle and then immediately turned to powder. The law of angular momentum says that it should of continued at that angle but it kinda sat up and poof -dust!
Much is made of the fires in those buildings but the first responders on the scene called for one more hose (for a total of 2). Additionally, if you remember your extensive naval fire fighting training, the black smoke and red flames indicate a fire that was burning poorly. The fuel probably pretty much extinguished itself within 8 minutes or so and was a class A fire at that point with papers and office furniture soley fueling the fire. Hardly a major conflaguration by any stretch. In some photo's you can see an office worker on the floor looking out of the building which indicates that the temperature was not terribly excessive, at least in that one building.
I definitely agree that OBL would have benefitted more if the buildings had remained upright.
Finally, I point out again that Silverstein slipped and said that he told them to "pull it" and now, Senator Kerry is saying that it was demo'd. In your educated opinion, how long would they require to set up WTC 7 to fall like it did (pretty much picture perfect)?
I never made it onto a sub, went to BEEP (Basic ELectronics) at San Diego RTC, Electronics "A School" at Great Lakes and to Groton in late 1978 or 1979. I was in Idaho finishing the SG6 reactor training (Navy had a facility there. I understand that it's in New London now.) when they talked to me about transferring to a Crypto rating with a bonus and an E5 rate after Crypto A school as icing on the cake (as an advanced electronics recruit I had E3 going in and E4 outta A school) and unfortunately, TWO more years of active duty commitment. Ironic because I originally wanted to go into Crypto or Electronics warfare but I told 'em I had smoked pot once so, despite an ASVAB score of 98, they said no (but we'll let you play with a nuclear reactor, go figure...). I was 4.0 all the way through school and made E7 (CPO) before leaving for government service as a civilian for another 2 years.Where'd you sail from?
I sailed from Norfolk after sub school and San Diego after I had my steaming certificate. No Boomers in my history.
I've watched quite a bit of the video of the towers. I really don't know where you get the idea that it wasn't a hot fire above the impact points. It was so hot that people are jumping out of windows 10 and more floors above where the smoke is coming from the windows. That tells me that there was a lot of heat. People that aren't in smoke don't jump out of windows unless they are being roasted. Also, if they thought that they could work past the fires at the impact points, they would have. Even civilians aren't that determined to die, which is what jumping out of a window ensures.
There isn't a lot of good video of the first tower collapse, the media had their cameras on the people jumping from the other one when it went and by the time they were trained on it, it's mostly the ejecta cloud. The second tower had a piece topple to the side as the bottom fell out beneath it and then there are two falls. The main body mostly into it's footprint and the piece that had gone sideways about 50 meters to one side. That's pretty consistent with a number of pillars having gone first before inertia sets in.
The main body mostly pulverized the lower floors as it collapsed into them and caused them, in turn, to collapse. The iconic pieces of the facade are actually from the piece that went down to the side. I actually thought most people knew that, the facade from the piece to the side was shown so often and is so clearly where the plaza was.
I'm pretty sure that there was a lot of relief when Building 7 collapsed at 5:20PM. I'm also pretty sure that is where the "pull it" comment originates. From about 11:00 AM to when it finally collapsed there was probably a lot of discussion about what the hell they were going to do with it. It was afire, the video shows flame in the windows from the 5th floor to the roof, it had an obviously fatal amount of damage and if it hadn't collapsed they would have had to engage in the procedure that I outlined in my previous post.
I outlined my reasons for rejecting the idea that they put a team in there and pulled it will it was still on fire. Just ask yourself, would you have gone in there, for any amount? You have to be alive to spend it and it's really not the same as some of the stuff I did for God and Country. I wouldn't put my handsome white ass on the line for an insurance company. I don't expect anyone with the necessary knowledge would.
You are forgetting that offices are full of stuff that has healthy amounts of fire retardant built in them. Of course the contents of the offices were burning poorly, that's specific to fire regulations and their design. That they burned at all says that there was something very hot keeping the office contents on fire.
It's the reason that we chip paint. We don't want all the toxic gasses that layer over layer of paint, carpet and wall coverings produces. We want the fire to flash the paint of the wall so that we can go in and cool the area down.
Specifically on C4.
If I was doing it, I wouldn't use C4. Especially if the plan included crashing aircraft full of jet fuel into the area that I wanted to have a controlled explosion in. I used to do this safety demonstration where I put a book of matches into a (small) piece of C4 and of course the C4 immediately ignites. C4 is a field expedient cooking fuel.
Once you have all that heat, the C4 will liquefy and will not be a shaped charge any longer. You can't collapse the building if your shaped charges didn't hold up in the designed locations while you waited for the media to film the fires.
That's the huge problem that the conspiracy theory has. The theory basically states that one of two systems was used. Both have reasons that they can't work.
Theory 1
There were some suicidal dummies acquired from some unknown source that went into burning, damaged buildings and set up a controlled demolition. I really don't think I have to elaborate further on why that's idiotic.
Theory 2
There was a plot where the charges were set in advance and after crashing planes into the buildings and allowing ample time for the media to get good video, the charges were set off.
My reasons for rejecting it:
There are a number of types of explosives that could be used. C4 wouldn't work because it would liquefy and migrate away from the desired location.
Thermite wouldn't work because it's kind of sensitive to heat. I can't think of a way where I could guarantee that the charges wouldn't predetonate while I was waiting for the media to get their pretty pictures. If the charges had predetonated, the media would have captured at least one of the hundreds of incidents and your cover would be blown once someone like me looked at the pictures.
Nitro wouldn' work for the reasons above. Dynamite is a form of Nitro, ineligible for the same reason.
That leaves the 2 part explosives. You apply the explosive powder (fertilizer works) and then introduce the carbon in the form of a liquid immediately prior to when you want to set it off.
For the reasons that I reject the post crash theory, you have to have a tank with a control device at the location of each explosive device so that you don't have to go into the building.
So, you have drilled into the support structures, you have placed 100 pounds of fertilizer at each desired location, you have a tank with the diesel fuel at each desired location, you have a control device to introduce the diesel fuel into the fertilizer and you have a control device to set off the explosion when desired.
None of the control devices was set off by somebody using a cell phone. Nobody noticed the large, bulky explosive devices and tanks. It all worked when desired.
What are the chances of that?
I'd have a better chance with a lotto ticket.
Silky, you are not reading very carefully.so how did evry joint and beam bolts screws all fail at the same time for the building to unpleel like a babana at freefall speed???
u realize this has been simulated by ppl outside the handpicked 911 commision.
look up Steven E Jones. Basically simulation shows the collapse would take 45-60 seconds........
If u have a prob with that u have a prob with physics
They don't count any of the private contractors either.Does Iraq seem any free'er or safer??? 655,000 civilians dead? 12,000 us troops dead, if u die in the UK or Germany(Rammstein airfield) from injuries IN Iraq they dont count those.....
