One of probably dozens of alerts that had previously come to nothing. Avoidable disasters happen because of incompetence and information overload
I was in NY days before 9/11 and I'd never seen such an open city, in none of the great buildings i visited was i once asked to open my shoulder bag or searched, at the time i thought to myself what a soft target the city was
When i few from LaGuardia to Atlanta (for $25) i could have paid by cash and called myself Saddam Hussein. Like during Pearl Harbour the US was on a complacent peace footing.
No steel framed building fire has ever been fuelled by thousands of gallons of aviation kerosene before. Nor are most steel framed buildings so full of flammable material such as thousands of tones of paper, furniture and fittings to soak up that kerosene
I don't doubt that the impact and fires would have caused the collapse of the towers but there is one bit that I have never understood.
I would have anticipated that the supports on one side of the building would have failed, causing the tower to twist and fall sideways. Maybe one side would collapse dragging the other side towards it. I would never had anticipated that a building would pancake straight down into it's own footprint, as all 3 did.
A sideways collapse was probably intended, the aircraft flew into the towers from north and south.
Fred DIbnah used to fell mill chimneys like this; he'd gradually cut out the brickwork on one side, inserting temporary timber supports. He'd then burn out the timber supports and the chimney would fall like a tree. Why didn't the twin towers fall like that, if the supports had been asymmetrically damaged and burnt?
If you wanted to get a building to collapse straight down, I would have thought that you would need to sever all the vertical supporting columns simultaneously to achieve that. I'd think you could only achieve that with a controlled explosive demolition. I admit that I have no expertise in these matters.
There was a link posted on here some months back of the collapse of WT7, which showed a line of simultaneous puffs of black smoke, all at the same level, at the start of the collapse. I thought it looked very like an explosive demolition. What was it? Had someone photoshopped the video?
Quite, I've seen people walk right up to the gates to meet people; folks checking in guns, knives, hunting vests and ammo right on the tarmac on internal flights to the states. I've also met a couple of academics from the university that taught the Saudi boys how to take off. At the same conference met a Saudi academic who was be moaning the fact that no young Saudis wanted to go to university since daddy owned an oil well and all the had to do was go to prayers and spend the rest of the day drifting. Foreign infidels do all the work for them.
I really don't see why people have difficulty with all this. It only takes one floor to give way and the weight and force of the building above collapsing onto the next floor causes the pancaking effect.
The air between those floors has to go somewhere, explaining the puffs of air/black smoke out the sides as it falls.
One of the ironic thing about conspiracy theorists is their moronic ability to accept all sorts of things as truths without any degree of sceptical analysis or fact-checking, as long as they further the hypothesis (as the hypothesis comes first, unlike in rational thought).
Yes, if the one floor goes straight down. If one side of a floor collapses, the floor below will collapse at the same side; the building falls sideways.
The question remains the same. How would you get one floor to go straight down to initiate a straight-down collapse of the building? Is it likely that would happen?
Progressive collapse is a well known phenomena. Once one floor fell and knocked out the one below, it was 'goodnight Vienna' for the lot.
Dibnah ate away at the chimney BASE. this collapse started halfway up. Essentially one vertical section collapsed, and the impact of the storeys above was enough to wreck the lot.
Indeed. You are half right, except what took out the 4 corners wasn't a controlled explosion, it was the impact of the floor and the building above falling on to it. Once any weakness started, the floor simply fell out of the structure and went straight down. I cant remember the exact details, but any slender column is liable to catastrophic buckling if the lateral restraints are removed from the elements. Google Euler instability etc.
What stops the vertical buckling is horizontal members connecting them: those were essentially the floors IIRC. Once a floor unit went, nothing held the columns in place, and they were already weak from the blaze.
Don't think 'tree' think 'tall pile of concrete and glass cards, tied together by relatively weak steel ties' once those ties go, the thing collapses like a house of cards.
It was the first floor to go collapsing onto the one below,probably blowing out the windows. .
You simply dont understand what a building is, engineering wise, especially a tall steel and concrete one.
For it to fall sideways implies it retains enough structural integrity as it falls to transit lateral loads to upper storeys to accelerate them sideways. It cant do that if its effectively been sliced in half in the middle.
Think of a pile of really heavy concrete biscuits, separated by cocktail sticks. balanced one on top of the other. Now at a given layer start removing coccktail stiicks. You cant push the lot over, because there is simply no strength in bending: remember the ONLY lateral loads it was designed for were high winds. Even an airliner ramming into it didnt knock it over, because its so HEAVY. nothing is going to make it fall sideways.
Its *guaranteed* to happen. If you lose structural integrity due to fire at one level, affecting a large fraction of the 'cocktail' sticks, sooner or later one, two three go, the floor sags, and at some point the rest go more or less simultaneously - as one goes there is overload on the next..you take out a complete layer of cocktail sticks..
Without a redundant, and much more expensive structure, progressive collapse is almost 'designed in' to any large structure.
If any fire protection material that could cope with an airliner collision at full speed exists, I would be surprised. The WTC had sprayed on material on the steel beams, naturally such stuff is fairly crumbly and works by ablating and taking heat with it. It isn't mechanically strong.
AIUI, most of the vertical load-bearing in the towers was through the central core, so punching a big hole in the side or in one corner isn't going to matter much.
Not sure that was true..however one reason no one gout out above the fire, was that all the core was also on fire and destroyed.
And its where all the lifts and stairs were.
So it doesn't make a lot of difference.
No steel building is designed to withstand a fire. Its designed to delay structural damage to allow people to get out, and firefighters time to get the fire under control.
In this case it was so extensive a fire that people could not get out, no could the fire be brought under control.
Yes! And that's the whole point. The paint is activated by high temperatures to form an insulating char (a bit like polyurethane foam, only much harder) that protects the steel from the heat and stops it from softening.
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