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jonno99
(2,620 posts)
wildbilln864
(13,382 posts)thus far they never fail except when in a controlled demolition scenario.
jonno99
(2,620 posts)wildbilln864
(13,382 posts)I say never because in this case it has never happened. The towers were built to withstand a fully loaded 747 crashing into them at 400 mph. They were built to withstand 100 mph hurricane force winds! So what external force could you imagine besides incendiary/explosive demolition please ?
jonno99
(2,620 posts)Last edited Tue Sep 13, 2016, 10:50 AM - Edit history (1)
use of explosives. And these are not just govt. types, but engineers, architects, etc.
My suggestion is to give yourself permission to be open to other ideas about what happened; lose your preconceived notions, and see if there might not be a more rational explanation than a huge, multifaceted scheme to bring down (at least) three of the WT buildings - a scheme that must have involved dozens, if not hundreds of individuals.
And all of this pulled off without a hitch - flawless execution; and best of all, nobody has squealed!
The perfect crime.
hack89
(39,180 posts)
nationalize the fed
(2,169 posts)nationalize the fed
(2,169 posts)
AtheistCrusader
(33,982 posts)It meets the claim just fine.
It did NOT sustain the subsequent fire.
That said, the building was lucky. The impacts imparted some 7.4 million foot-tons of torque on impact. Building codes for wind loads on those buildings (Hurricane force winds) only required it to withstand 4 million foot-tons of torque. The buildings were stronger and resisted the impacts BETTER than could possibly be hoped for.
The impacts didn't bring them down. Fire did. The impacts only spread the fires, broke the fire suppression systems, and reduced the total physical strength of the building, leaving it more vulnerable to the fire, and harder for the fire to be fought.
Have a nice day, with your irrelevant truther points that are ridiculously easy to dismiss.
whitefordmd
(102 posts)That does not mean what you think it does.
marble falls
(62,441 posts)nationalize the fed
(2,169 posts)https://www.nist.gov/engineering-laboratory/faqs-nist-wtc-7-investigation
The First and Only time in history. No fire codes changed.
http://ae911truth.org
2500+ Professional Architects and Engineers have put their careers on the line to sign a petition for a new investigation. That's a lot more than what most "debunkers" have done.
hack89
(39,180 posts)Because when I google "fire code changes due to 911" I get lots of sites with lots of specific examples of fire code changes.
In fact, 911 is commonly said to have resulted in the most comprehensive fire code changes in our history.
Separation
(1,975 posts)People also look over the fact that quite a bit of the fireproofing was knocked off of the steal from the impact of the airplane. Its also been proven that steel will fail before it reaches its melting point. Another thing I laugh at when people say that jet fuel cant melt steal beams. Of course it cant, but it cant weaken it to the point of failure. Which has been proven time and time again.
AtheistCrusader
(33,982 posts)The conspiracy theory only resonates with people who have no fucking clue how materials work/engineering/etc.
I came in here thinking to see HERP DERP APARTMENT BUILDING IN THE UK, so they are getting slow on the draw. I was all ready to point out it's made of CONCRETE, but they're still sleeping apparently.
captain queeg
(11,780 posts)I'm an engineer. Its not like we have a lot of similar occurrences to measure this event. The failure of the buildings seems odd to me, but I don't have any idea of the structure underneath.
I would question that statement about being designed to survive a 747 traveling at 400 mph, mostly because even if they did consider a jetliner hitting it, they'd have assumed a more normal speed, and that certainly wouldn't be anything like 400 mph near the ground. Energy is proportional to the velocity squared so 400 mph would have 4 times the energy of a plane going at 200 mph. That being said I'm not saying its impossible, just seemed to me like the collapse was too uniform.
jberryhill
(62,444 posts)Construction of the towers began in 1968. The first 747 flight was 1969. I think it's pretty obvious that the towers weren't "designed" for impact of a non-existent aircraft.
AtheistCrusader
(33,982 posts)but yeah, it's nonsense. One of the aircraft was going BEYOND VNE at the time of impact. (Velocity-Never Exceed cockpit warning)
The engineers envisioned a 707 limping in to the airport on one engine, not a fully laden-fueled 767 going full-tilt-boogie.
sdfernando
(5,408 posts)Per Wikipedia:
"In the 1960s, when the World Trade Center was being designed, this B-25 impact incident served as motivation for the designers to consider a scenario of an accidental impact of a Boeing 707 into one of the twin towers.[citation needed] The towers were destroyed when two Boeing 767s were intentionally flown into them during the September 11 attacks of 2001."
https://en.wikipedia.org/wiki/B-25_Empire_State_Building_crash
marylandblue
(12,344 posts)It something the lead designer considered but it wasn't in the specs. He just did some quick calculations and made the claim that the building could withstand the hit. But nobody checked the calculations then and they no longer exist for anyone to check them now.
sdfernando
(5,408 posts)
MosheFeingold
(3,051 posts)There is no lateral load after the initial impact, and given the near free-fall collapse, there was insufficient time for portions to attain significant lateral velocity. In fact, I suspect there would be too much inertia to fall in any direction other than nearly straight down.
captain queeg
(11,780 posts)But I am not referring to forces, I am referring to the damages. Its not like the plane caused damage uniformly at some level, it was on one side, so the damages would be far greater there. If the steel is melting or burning on one side before the other, that side would tend to slough off first.
AtheistCrusader
(33,982 posts)This is evident from every single top-down photo of the aftermath, and any financial analysis of the various surrounding buildings repair costs.
Falling into their footprints is an ignorant, meme. They clearly did NOT fall directly down. But neither did they topple like a fucking tree, nor could they have under any circumstance, short of the earth suddenly halting rotation, and inertia taking care of the rest.
captain queeg
(11,780 posts)Also, what the hell is a redundancy factor? I guess the meaning can be inferred, but have never seen or heard of that term before. Why engineer a building at all if you plan on overdesigning that much? The idea is to build something that is safe from foreseeable circumstances with a reasonable factor of safety (somewhat different than what I would expect a redundancy factor might mean). This gives the best economical solution and I assure you whoever paid to build those things didn't over design more than necessary. Back in the old days things were way overdesigned because methods were not as sophisticated.
Ptah
(33,521 posts)
In ASCE 7 it is a factor applied to seismic loads when certain low-redundancy conditions are met.
For ASCE 7-05: For structures assigned to SDC D, E, and F, ?=1.3 unless one of the following two conditions is met, then ?=1.0 (12.3.4.2):
1) Each story resisting more than 35% of the base shear in the direction of interest shall comply with Table 12.3-3.
2) Structures that are regular in plan at all levels provided that the seismic force-resisting systems consist of at least two bays of seismic force-resisting perimeter framing on each side of the structure in each orthogonal direction at each story resisting more than 35% of the base shear.
(The number of bays for a shear wall shall be calculated as the length of shear wall divided by the story height or two times the length of shear wall divided by the story height for light-framed construction.)
ASCE 7-10 changed slightly on the redundancy factor but is more or less the same.
http://www.eng-tips.com/viewthread.cfm?qid=378280
Looks like you need to do some more reading about redundancy factor.
captain queeg
(11,780 posts)Seriously dude, 28,000 + posts? You must be so knowledgeable about EVERYTHING.
Ptah
(33,521 posts)I answered you.
AtheistCrusader
(33,982 posts)to a direct inquiry.
go on, with your bad self.
gyroscope
(1,443 posts)Raging fires on almost every floor that burned much longer and more widespread than the Twin Tower fires and engulfed the entire building compared to the fires limited to a couple of floors of the Twin Towers, why did it not collapse like the Twin Towers or WTC 7?
AtheistCrusader
(33,982 posts)Concrete spalls and can burn, and that building is seriously damaged, but it does not lose strength like steel does as it heats, and it does not expand like steel does as it heats.
gyroscope
(1,443 posts)Are there are any examples apart from the WTC towers?
marylandblue
(12,344 posts)collapse occures around 45 seconds in
[link:
gyroscope
(1,443 posts)Still standing after fire was put out.
marylandblue
(12,344 posts)On the left side, you are lookinf at the back half of the building, after the front half collapsed, as yoi can see on the video.
AtheistCrusader
(33,982 posts)fire.
The building was hybrid concrete/steel The floors below the 2nd Technical Floor are all concrete and survive the fire. Above the 2nd Technical Floor, the building was framed in steel with a concrete core, because steel allows for smaller support columns and expansive views for conference rooms and expensive penthouses.
The fire started from a small electrical fire, and spread, and 2 hours in, the steel areas of the building were collapsing and raining down into the street like molten butter. After the fire, all that remained was a few beams here and there, bent and sheared off by the heat, and the concrete.
And that's from a conventional fire that spread from a single ignition source, with no airliner impact and fuel to spread the fire all over the place.
gyroscope
(1,443 posts)steel can lose its strength to the point of complete failure after burning for a couple of hours.
if that were the case then all of our steel pots and pans would be completely useless for cooking.
The Twin Towers were a giant heatsink. The heat would be absorbed and dissipated by all 110 floors of steel framing before it could do much damage to any part of it. It doesn't just simply get hotter and hotter at one point or one floor of the building, because the heat is dissipated throughout the massive structure. Which makes it impossible for fire to weaken any of the steel to the point of catastrophic failure.
marylandblue
(12,344 posts)Your pots and pans are not under high compression as in a building. Steel doesn't lose all it's strength, but becomes weak enough to fail when.it has to.carry a heavy weight.
As gor.the heat sink issue, this is covered by the heat conduction properties of steel, which are high, but not infinite. You can put a steel bar in fire and still hold the other end in your hand.
gyroscope
(1,443 posts)Structural steel doesn't weaken enough to collapse after limited exposure to a relatively minor office fires that lasted less than two hours. Especially given the heatsink nature of steel-frame buildings.
Even if it were somehow true that the WTC steel did weaken enough to partially collapse at the top, it makes no sense at all that it would cause the ENTIRE 110 story building to fail and come down when the fires were limited to a couple of floors near the top of the building.
marylandblue
(12,344 posts)The WTC was also insulated but the plane impact stripped off some of the insulation. See also prior video of partial collapse of a steel building.
As for the whole building, that's called a progressive collapse. Few if any buildlings were designed to withstand progressive collapse back then. Since 2001, some now are.
gyroscope
(1,443 posts)Yet many steel-frame buildings built before 2001 have caught fire but none of them collapsed.
You can't even name one that did.
marylandblue
(12,344 posts)It's rare, but it happens. It happened in the 1995 Oklahoma City Bombing.
gyroscope
(1,443 posts)so you admit explosives were used to bring down the WTC towers, gotcha.
marylandblue
(12,344 posts)And don't forget to check on what can cause it, including but not limited to: fire, explosion, earthquake, structural damage from any source, poor building design, poor temporary support design during construction.
A case of progressive collapse due to flooding and poor design.
gyroscope
(1,443 posts)...thanks for proving my point.
marylandblue
(12,344 posts)Response to gyroscope (Reply #48)
marylandblue This message was self-deleted by its author.
AtheistCrusader
(33,982 posts)It is indistinguishable from an explosive.
WTC towers 1 & 2 represented 200 acres of office equipment, electrical systems, UPS's, and heavy machinery. 1/3 of which was 'inelegantly' disconnected from the grid during the impacts, and all of which was violently disconnected from the grid when the towers collapsed.
200 acres of 'city' could not be easily disconnected from the grid any more than it could be disconnected from the water mains, when it came down and destroyed those too.
gyroscope
(1,443 posts)Too bad the government doesn't buy it.
NIST WTC 7 FAQs
25. Did the electrical substation beneath WTC 7 play a role in the fires or collapse?
No. There is no evidence that the electric substation contributed to the fires in WTC 7. The electrical substation continued working until 4:33 p.m. on Sept. 11, 2001. Alarms at the substation were monitored, and there were no signals except for one event early in the day. No smoke was observed emanating from the substation.
AtheistCrusader
(33,982 posts)I said something about sounds that might be confused with explosions. (Hours before the building actually collapsed)
Why is that difficult for you to follow?
AtheistCrusader
(33,982 posts)AtheistCrusader
(33,982 posts)2 hours in, the steel areas of the building rain down into the street, having lost all strength required to keep the floors up. After the fire, all that remains is concrete.
Your stove doesn't get as hot as an office furnishing fire.
marylandblue
(12,344 posts)From the Cardington Fire Test - notice the bent and twisted steel frame
gyroscope
(1,443 posts)then one might expect to see the floors above the impact zone collapse, not the whole entire building. and only then if you:
1. disregard the length of the fire in the experiment compared to the brief fires of the twin towers.
2. you disregard the heatsink effect of a massive 110 story skyscraper.
marylandblue
(12,344 posts)Regarding floors collapsing above fire floors, try this (thought!) experiment
1) Place a ten iron weight on your head.
2) Record the amount of pain you feel
3) Take the same ten pound weight and hold it ten feet above your head.
4) Drop the weight on your head.
5) If you are still conscious, record the amount of pain you feel.
6) If you are not dead, go to the hospital, you probably have a fractured skull.
For length of fire - fires in World Trade Center burned about an 1 hour. This is also about the time that the maximum temperature in the Cardington Fire Test was reach, with a fairly rapid drop off after that.
Heatsink effect - I don't think you understand how a heatsink works. I suggest you read Transport Phenomena, by Bird, Stewart and Lightfoot, which is the standard introductory text for topics such as heat transfer.
I also suggest you read more about the Cardington Fire Tests here:
http://www.mace.manchester.ac.uk/project/research/structures/strucfire/DataBase/TestData/default1.htm
Reading these references will help make you a better conspiracy theorist.
gyroscope
(1,443 posts)but thanks for the laugh.
You still haven't named a single real world example of steel-framed high rises collapsing from fire. You can dream up all the wildest theories in the world, but there is a difference between the real world and the world of make-believe. But you don't seem to make any distinction.
marylandblue
(12,344 posts)And think it wasn't a collapse, but okay. Suit yourself.
AtheistCrusader
(33,982 posts)All the concrete remained standing. All the steel collapsed to the street. No plane involved.
gyroscope
(1,443 posts)Note the part in upper case.
---------------------------------------------
The Behaviour of Multi-storey Composite Steel Framed
Structures in Response to Compartment Fires
Susan Lamont
Doctor of Philosophy, University of Edinburgh, 2001.
Forward from Susan Lamont:
For many years the ability of highly redundant composite framed structures to resist the effects of fire has been undervalued and largely misunderstood. This was first realized when, after a number of real fires in multi-story composite steel framed structures structural failure did not occur. The Broadgate Phase 8 fire is probably the most notable. This accidental fire happened during the Construction phase when the steel frame was only partially fire protected. Despite very high temperatures during the fully developed phase of the fire and considerable deflections in the composite slab there was no collapse. THIS INITIATED CONSTRUCTION OF AN 8-STOREY COMPOSITE STEEL FRAME AT BUILDING RESEARCH ESTABLISHMENT LARGE SCALE TEST FACILITY IN CARDINGTON. SIX FIRE TESTS WERE CONDUCTED, OF VARYING SIZE AND CONFIGURATION, TO OBSERVE AND ULTIMATELY EXPLAIN WHY COMPOSITE STEEL-FRAMED STRUCTURES ADOPT VERY LARGE DEFLECTIONS DURING A FIRE BUT DO NOT COLLAPSE.
Declaration
This thesis and the research described and reported within has been completed solely by Susan Lamont under the supervision of Dr A.S. Usmani, Prof. D.D. Drysdale, Dr B. Lane and Prof. J.M. Rotter.
Where other sources are quoted full references are given.
Susan Lamont, 29th September 2001.
https://www.era.lib.ed.ac.uk/handle/1842/1485
http://911research.wtc7.net/mirrors/guardian2/fire/SLamont.htm
marylandblue
(12,344 posts)Based o your research, where are the large deflections and why would anyone think those large deflections would cause a building to collapse in the first place?
gyroscope
(1,443 posts)the fire and resulting deflections would have to occur at the base of the building, as the photo you posted depicts.
Because the entire weight of the building rests on the steal beams at the base, so in this scenario it is somewhat plausible the building could conceivably come down completely from the combination of intense fire and the weight of 110 stories causing the steel at the base to deflect and fail. (But even in this best case scenario, the Cardington tests say the towers would not collapse).
However the fire took place near the top of the towers not the bottom. Making it absolutely inconceivable and not plausible at all, that such a fire way at the top would cause the whole entire structure to collapse and freefall upon itself.
marylandblue
(12,344 posts)You need to brush up on your structural engineering.
gyroscope
(1,443 posts)because in the real world fires do not cause modern high-rises to collapse.
marylandblue
(12,344 posts)Last edited Fri Jun 16, 2017, 03:52 PM - Edit history (2)
Indicating perhaps you don't know where the deflection is or what significance the test has for building design. Put another way, if you actually wanted to make a building that could stand in normal conditions, but would collapse in a fire, what could you do, without changing the size of the columns that would make the building more likely to collapse?
AtheistCrusader
(33,982 posts)The largest steel battleship ever built by the hand of man. Approximately 70 thousand tons.
Drop 70k Tons 20 feet, what is the equivalent energy?
(Hint: The largest wrecking ball ever made by the hand of man)
North tower's mass above the impact point/fire was approximately that of the mass of the largest battleship of WWI's era, still a huge ass wrecking ball. And the mass gets larger as it accumulates more wreckage on the way down.
marylandblue
(12,344 posts)Calculate the kinetic energy of the top of the building after it fell 20 feet and the resultant pressure on the bottom of building. Compare this pressure to the pressure generated by the top of the building at rest.
gyroscope
(1,443 posts)which was never struck by an airplane. so there goes your theory.
marylandblue
(12,344 posts)so I don't see why we can't talk it now. It's obvious you don't know how to calculate kinetic energy, which is high school physics.
Nonetheless, let's see how much you know about WTC 7. There was something unusual about the WTC 7 that could have affected building performance. Few, if any, other buildings in the world have ever been designed this way. What is the unusual design feature?
AtheistCrusader
(33,982 posts)Poster above will also not be able to calculate the expansion of a 75 foot steel beam when heated to 800c.
marylandblue
(12,344 posts)But you are correct, he will not be able to calculate the expansion or even understand what happens when a beam expands.
gyroscope
(1,443 posts)a smaller object cannot destroy a much larger object before destroying itself first, when both are made of the same material. that only happens in cartoons. the pile driver theory is a joke.
marylandblue
(12,344 posts)Last edited Mon Jun 19, 2017, 10:52 PM - Edit history (1)
"Every action has an equal and opposite reaction" to "a smaller object cannot destroy a much larger object before destroying itself first when both are made of the same material?"
For full credit please show your work. So far, you have earned the following grades
Energy Equation - 0
Heat Transfer - 0
Structural Steel Design - 0
Fire Engineering - 0
Force and Pressure - 0
But there is still hope for you. Having failed College and High School physics topics, you might be able to pass elementary school science if you could explain how Newton's Third law applies to this situation.
gyroscope
(1,443 posts)What is the old saying? If you can't dazzle them with brilliance, baffle them with BS. lol
marylandblue
(12,344 posts)While you make up nonexistent physical principles. So carry on with your own BS. Conspiracy theorists always do.