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[Lordo]

All the evidence is in the first clip how and why the building collapsed.

Main culprit was the fact that explosion blew away the fire protection and the second culprit was the fuel which burnt and weakened the bolts between the trusses and the brackets.

Listen to the Construction and Fire engineers. The answer is there.

They are only now designing such fire protection that could withstand explosion.

https://gizmodo.com/the-bomb-proof-miracle-materials-that-will-make-the-fut-5994745

But surely it is far cheaper for the yanks to fuck off from where they do not belong so they do not antagonise and harm people and then bang, people will not want to cause them harm.

[Robin Hood]

cyprusgrump:

May I politely suggest that you look on Wiki to see how The Empire State Building was constructed...?

It took 210 steel columns to construct the vertical frame of the building. Steel girders would only be raised 30 stories at a time so cranes were used to pass them from floor section to floor section to complete the frame. Rivets were placed by hand by teams of four.

You may ... and I did!

You did me a favour as I realised ‘steel framed’ is not the correct description for WTC1 and WTC 2! They are really ‘steel cored’ buildings! You have posted what makes the difference.

The Empire State has 210 steel columns with horizontal floor beams riveted though joint plates to the columns, giving stability and also distributing the building load. Empire State distributed the whole load over 210 vertical support columns, the Twin Towers concentrated the load over 47 fabricated columns and the horizontal supports bore floor loading only. This was centered inside a fabricated tube made of spandrels that took half the load of the floors and went from ground level to roof level as a self supporting structure. At the top the central columns and the outer spandrel 'tube,' were brought together by the Hat Truss, The other half of the floor load was taken by the central core.

Clearly, two very different methods of construction, that will react differently in the same catastrophic scenario?

The Twin Towers were far more likely to topple if the support core was damaged on one side because then the load above would not be equally supported. When the remaining steel heated up by all this fuel and was softened...... as Newton says ..... it will take the line of lease resistance to gravity and topple! I suppose you could say, as would have happened on 9/11 if ‘something’ had not removed the opposing force of the central column?

All that needs to be done is to explain what happened to 47 massive, and mainly undamaged steel columns, getting progressively bigger, the lower down the building you go? I have expressed my theory of how this could have happened and why taking advance measure to demolish the buildings would be a sensible precaution? That 4” light concrete floors collapsing could also do that ..... is another theory ...... what’s yours?

But thank you ..... I learned something from you today!

[cyprusgrump]

cyprusgrump:

May I politely suggest that you look on Wiki to see how The Empire State Building was constructed...?

It took 210 steel columns to construct the vertical frame of the building. Steel girders would only be raised 30 stories at a time so cranes were used to pass them from floor section to floor section to complete the frame. Rivets were placed by hand by teams of four.

You may ... and I did!

You did me a favour as I realised ‘steel framed’ is not the correct description for WTC1 and WTC 2! They are really ‘steel cored’ buildings! You have posted what makes the difference.

The Empire State has 210 steel columns with horizontal floor beams riveted though joint plates to the columns, giving stability and also distributing the building load. Empire State distributed the whole load over 210 vertical support columns, the Twin Towers concentrated the load over 47 fabricated columns and the horizontal supports bore floor loading only. This was centered inside a fabricated tube made of spandrels that took half the load of the floors and went from ground level to roof level as a self supporting structure. At the top the central columns and the outer spandrel 'tube,' were brought together by the Hat Truss, The other half of the floor load was taken by the central core.

Clearly, two very different methods of construction, that will react differently in the same catastrophic scenario?

The Twin Towers were far more likely to topple if the support core was damaged on one side because then the load above would not be equally supported. When the remaining steel heated up by all this fuel and was softened...... as Newton says ..... it will take the line of lease resistance to gravity and topple! I suppose you could say, as would have happened on 9/11 if ‘something’ had not removed the opposing force of the central column?

All that needs to be done is to explain what happened to 47 massive, and mainly undamaged steel columns, getting progressively bigger, the lower down the building you go? I have expressed my theory of how this could have happened and why taking advance measure to demolish the buildings would be a sensible precaution? That 4” light concrete floors collapsing could also do that ..... is another theory ...... what’s yours?

But thank you ..... I learned something from you today!

Oh, so have the 'Secret Service' wired up all the Steel Columned buildings with explosives or just the Steel Cored buildings...?

It would be a bugger if they had thousands of guys sitting next to buildings with detonators on the off chance of a terrorist attack and the buildings were not vulnerable after all!

[Robin Hood]

cyprusgrump:

May I politely suggest that you look on Wiki to see how The Empire State Building was constructed...?

It took 210 steel columns to construct the vertical frame of the building. Steel girders would only be raised 30 stories at a time so cranes were used to pass them from floor section to floor section to complete the frame. Rivets were placed by hand by teams of four.

You may ... and I did!

You did me a favour as I realised ‘steel framed’ is not the correct description for WTC1 and WTC 2! They are really ‘steel cored’ buildings! You have posted what makes the difference.

The Empire State has 210 steel columns with horizontal floor beams riveted though joint plates to the columns, giving stability and also distributing the building load. Empire State distributed the whole load over 210 vertical support columns, the Twin Towers concentrated the load over 47 fabricated columns and the horizontal supports bore floor loading only. This was centered inside a fabricated tube made of spandrels that took half the load of the floors and went from ground level to roof level as a self supporting structure. At the top the central columns and the outer spandrel 'tube,' were brought together by the Hat Truss, The other half of the floor load was taken by the central core.

Clearly, two very different methods of construction, that will react differently in the same catastrophic scenario?

The Twin Towers were far more likely to topple if the support core was damaged on one side because then the load above would not be equally supported. When the remaining steel heated up by all this fuel and was softened...... as Newton says ..... it will take the line of lease resistance to gravity and topple! I suppose you could say, as would have happened on 9/11 if ‘something’ had not removed the opposing force of the central column?

All that needs to be done is to explain what happened to 47 massive, and mainly undamaged steel columns, getting progressively bigger, the lower down the building you go? I have expressed my theory of how this could have happened and why taking advance measure to demolish the buildings would be a sensible precaution? That 4” light concrete floors collapsing could also do that ..... is another theory ...... what’s yours?

But thank you ..... I learned something from you today!

Oh, so have the 'Secret Service' wired up all the Steel Columned buildings with explosives or just the Steel Cored buildings...?

It would be a bugger if they had thousands of guys sitting next to buildings with detonators on the off chance of a terrorist attack and the buildings were not vulnerable after all!

Sarcasm is the lowest form of wit and a response from someone lacking a credible answer. So I won't bother to grace that with a reply!

[cyprusgrump]

cyprusgrump:

May I politely suggest that you look on Wiki to see how The Empire State Building was constructed...?

It took 210 steel columns to construct the vertical frame of the building. Steel girders would only be raised 30 stories at a time so cranes were used to pass them from floor section to floor section to complete the frame. Rivets were placed by hand by teams of four.

You may ... and I did!

You did me a favour as I realised ‘steel framed’ is not the correct description for WTC1 and WTC 2! They are really ‘steel cored’ buildings! You have posted what makes the difference.

The Empire State has 210 steel columns with horizontal floor beams riveted though joint plates to the columns, giving stability and also distributing the building load. Empire State distributed the whole load over 210 vertical support columns, the Twin Towers concentrated the load over 47 fabricated columns and the horizontal supports bore floor loading only. This was centered inside a fabricated tube made of spandrels that took half the load of the floors and went from ground level to roof level as a self supporting structure. At the top the central columns and the outer spandrel 'tube,' were brought together by the Hat Truss, The other half of the floor load was taken by the central core.

Clearly, two very different methods of construction, that will react differently in the same catastrophic scenario?

The Twin Towers were far more likely to topple if the support core was damaged on one side because then the load above would not be equally supported. When the remaining steel heated up by all this fuel and was softened...... as Newton says ..... it will take the line of lease resistance to gravity and topple! I suppose you could say, as would have happened on 9/11 if ‘something’ had not removed the opposing force of the central column?

All that needs to be done is to explain what happened to 47 massive, and mainly undamaged steel columns, getting progressively bigger, the lower down the building you go? I have expressed my theory of how this could have happened and why taking advance measure to demolish the buildings would be a sensible precaution? That 4” light concrete floors collapsing could also do that ..... is another theory ...... what’s yours?

But thank you ..... I learned something from you today!

Oh, so have the 'Secret Service' wired up all the Steel Columned buildings with explosives or just the Steel Cored buildings...?

It would be a bugger if they had thousands of guys sitting next to buildings with detonators on the off chance of a terrorist attack and the buildings were not vulnerable after all!

Sarcasm is the lowest form of wit and a response from someone lacking a credible answer. So I won't bother to grace that with a reply!

Oh, you do make me laugh!

[Lordo]

What is really interesting is the fact that the design of WTC1&2 buildings external skeleton managed to keep the collapse within the skeleton vertically even though it had become unstable after the trusses were being ripped off by the collapse. I suspect that's not what they were planning but it worked out well to contain the collapse to just within the frame.

[Robin Hood]

From all the videos we have seen of the collapsed buildings of the three World Trade Centers 1, 2 & 7, buildings 1 & 2 had collapsed top to bottom, indicating structural damage to the buildings where the aircrafts impacted the building by destroying the steel frames by the force of the impacting aircrafts and the intense fire following the explosions, regardless how much of the fuel from the planes went up in a ball of flames upon impact. There was enough fuel left to burn the several floors on each building to further weaken the remaining steel frames of the buildings.

The twin towers actually collapsed from the bottom up, above the impact point and THEN from the top down. It shows on the videos.
The impact would have had little effect on the core columns ..... they were fabricated from 25mm thick steel at the higher levels and 5" at the bottom levels.

An airframe is fabricated from 3mm thick aluminium and that had already been buckled and shredded going through the 1” steel outer columns. Only the engines and undercarriage units had any mass to speak of and any damage was most likely done by them ...... so the rest of the aircraft would have buckled and shredded like a Coke can!

The intense fire was outside the building .... not inside it. These aircraft fully loaded carried about 10,000 US Gallons of Jet A1 (Kerosine/paraffin) which is relatively slow burning and does not normally become an explosive mixture except when it is turned to a mist and ignited with plenty of air to burn, as we saw 80% of the fuel do with the towers.

Now look at the clouds of smoke belching from both of the towers? That indicates combustion with insufficient air to burn the fuel. The remaining 2000 gals of fuel ceased to have much effect from about two minutes after impact and most of that went down the lift shafts! The fires inside are ordinary office fires starved of oxygen. Not a lot of heat energy in that to heat up and weaken 1" thick steel plate!

I agree that normal heat generated by similar fires in other similar type of buildings would not have brought the buildings down, but this was not just a another fire in a building. These fires were way up the building where most of the floors hit by the planes were open to strong drafts blowing into the building, creating a furnace like heat where it would be very hot that would buckle steel frames, even if it weren’t hot enough to melt them. As most Cypriots know when preparing to start burning charcoal to make kebabs, we would first lay the charcoal and then place a large tin can that is open at both ends on top of the charcoal and fill is with more charcoal and light it. The tin can acts like a chimney that sucks the air from the bottom intensely which burns the charcoal fast and at a high temperature. This is how the fires got very intense in the Towers 1 & 2 to cause it to collapse.

Your BBQ tin can does not have a bottom in it or ‘floors’ at equal distances up to the top. The only way the air can get in is through the breaks caused by the impact. That is why the can in your BBQ does not belch smoke ....... it is open from bottom to top. The outer shells of the towers were virtually sealed tubes so there was little air from below and each floor was isolated from the floors above and below. The links between floors was through the central core. This I believe was shut off from each floor by a surrounding 2” thick fire resistant plaster board firewall mounted in a steel framework. So whether it was air going up or liquid fuel going down, it was very restrictive once you got past the immediate damaged levels.

There’s also the weight issue above the damaged areas of the buildings. North Tower was hit first by B-767 and the South Tower was hit second some 20 minutes later by B-757, and yet, the South Tower collapsed first considerable time before the North Tower despite being hit by a slightly smaller aircraft. The only difference between the two impact zones, is that the South Tower was hit at much lower part of the building than the North Tower, which meant that there was a greater weight above the impact area on the South Tower, which caused it to collapse first

That’s a fair description and explains the time difference between the two events.

The fire intensity and damaged steel frames from the planes hitting the buildings were more or less the same at the initial impact and the weight above the damaged areas falling onto the weakened structure below brought down the Towers one floor at a time from top to bottom at almost the speed of gravity.

If the spanning floors, which were mostly OUTSIDE the central core, collapsed in a pancake fashion floor upon floor, then it would not accelerate as all the kinetic energy is being used to destroy the floors and the massive steel columns below it and that would slow it down.

BUT ....... if the central core columns were severed say every two floors, because the floors were attached to both the outer tube and the central core, the descending columns would drag the outer walls in toward the center, shatter the light concrete floors ......but then BANG goes all that potential energy into thin air as light rubble and dust! Apparently, not one of the columns were found to be longer than two floor level spacing’s (36 ft).

But what is going to crush the central core which, as has been pointed out, supported half the weight of the mass of the building? You think that a cloud of crushed light concrete and some light floor trusses will crush something designed to proportionally hold up its share of the 250,000 tonnes of building above it. It wouldn’t ..... it would have to be removed to allow the free fall ACCELERATION ......... note, not speed.

World Trade Centre Tower 7 had collapsed from bottom to top, which meant that it was a controlled demolition and the fires in the 2-3 floors of the entire building at the higher floors of the building had nothing to do with the collapse of the building.

I agree with you. But, NIST says they ‘discovered’ a whole new phenomena that they could not explain, that would allow ordinary office fires to collapse a high rise steel framed building! Apparently an office fire around the 11th/12th NE corner floor area heated a floor truss and it expanded to push the supporting girder off its mount on the vertical common! And the whole building fell down ........ and for 2.5 secs. at free fall acceleration ...... yeah, of course that’s obvious ..... init?

Prof Hulsey and his team of scientists and engineers, carried out a scientific investigation using the most modern of software ....... and showed it didn’t work! Their conclusion was that every vertical column in WTC7 would have to have collapsed simultaneously to get the results seen in all the videos.

It’s a VERY long read ........
.
https://ine.uaf.edu/wtc7

[cyprusgrump]

The intense fire was outside the building .... not inside it. These aircraft fully loaded carried about 10,000 US Gallons of Jet A1

Quick Google, "How much fuel does a767 hold?"

24,140 Us Gallons...

You can't help yourself can you...?

And apart from the 3mm thick skin, have you heard of Wing Spars...? You know those immensely strong beams that have to support 24,140 US Gallons of fuel and two massive engines...?

[Robin Hood]

The intense fire was outside the building .... not inside it. These aircraft fully loaded carried about 10,000 US Gallons of Jet A1

Quick Google, "How much fuel does a767 hold?"

24,140 Us Gallons...

You can't help yourself can you...?

I suggest you do a bit more research before shouting your mouth off!

Inferno at the World Trade Center, NY Eduardo Kausel Professor of Civil & Environmental Engineering, MIT

http://web.mit.edu/civenv/wtc/PDFfiles/Chapter%20II%20Inferno%20@%20WTC.pdf

Quote ........ It has been reported that the towers were designed for the impact of a Boeing 707 aircraft then flying the skies. Considering that one of the towers survived for at nearly an hour, and the other almost two hours before collapsing, this demonstrated crash resistance provides compelling validation to this claim. It has also been opined by some that the towers did ultimately fail because the 767 is a far bigger jet carrying much more fuel than the design 707 aircraft. This view is largely incorrect.

The takeoff weight of a fully loaded Boeing 707-320 is 151 tons (336,000 lbs.), and it carries a fuel load of 87,000 liters (23,000 gallons) of jet fuel. By contrast, the maximum takeoff weight of a Boeing 767-200 is some 178 tons (395,000 lbs.), and carries a fuel load of 91,000 liters (24,000 gallons). Assuming that jet fuel weighs like kerosene, this represents some 74 tons (164,000 lbs.) of fuel, or about half the weight of a fully loaded aircraft. Thus, while the 767 is indeed a somewhat larger aircraft, it is not significantly so, while its amount of fuel load is nearly the same as in the 707. In addition, both ill-fated planes were only lightly loaded with passengers, and their fuel tanks at the moment of impact have been estimated to be no more than 50% full. Hence, these planes did not carry their full take-off load, but weighed instead no more than some 136 tons each.

cyprusgrump:

And apart from the 3mm thick skin, have you heard of Wing Spars...? You know those immensely strong beams that have to support 24,140 US Gallons of fuel and two massive engines...?

They are relatively light aluminium extruded beams. One beam at the leading edge and one at the trailing edge, separated by light aluminium ribs. They rely of maintaining total integrity to distribute the loads. Passing through a series of box columns made from 1" thick steel. at 500+mph, I think would probably affect that integrity ?

[cyprusgrump]

I suggest you do a bit more research before shouting your mouth off!

I'd suggest you read what you actually wrote (or pasted) before embarrassing yourself further...

These aircraft fully loaded carried about 10,000 US Gallons of Jet A1

To which I merely replied...

Quick Google, "How much fuel does a767 hold?"

24,140 Us Gallons...

Thereafter your credibility is somewhat diminished... So trying to convince us that a 767 is made out of Papier-mâché and couldn't possibly have damaged the structure of the building doesn't hold much water...


Sorry...