What about the WTC 1 Spire?

Originally posted by Another_Nut
reply to post by exponent

 

so you have gone from " likely" to "did" .

Yes, that might have been a little unclear so I apologise. I don't know what happened to those particular bottom columns as we don't have any video footage of it. However we know what happened to quite a lot of columns as they were studied by the BPAT/FEMA team. So we know that a large number did break apart at their welds.

They resisted the horizontal loads during the swaying. Therefore saying it was the horizontal loads that brought it down is flawed.

Only portions of the higher up columns swayed significantly. The whole structure lasted no longer than a few seconds. You can't make assumptions about what was happening at ground level from the actions of a few columns 500ft higher up.

The steel is not at ground zero. See photos.

I've seen the photos, I don't understand what you think is missing, nobody else seems to. Perhaps you're looking for something that isn't there? What exactly do you expect to see?

And still all 40+ failed at the same location? Look at the debris. All columns were severed within feet of each other.

edit on 14-12-2012 by Another_Nut because: (no reason given)

They were severed within feet of each other because the columns were built in identical lengths and welded together at the same points. 36 feet I think? I can't remember the core columns spacing.

reply to post by exponent


how do you know how far down they swayed? You said In Your response In that we can't see the bottom.

See my edit on page 6 for the amount of steel but i have it at

236 structural steel pieces found making each one aproxx 225 feet Long. Show me any evidence of this in the photo record.

And then explain where the steel for the Other building went.

Originally posted by Another_Nut
reply to post by exponent

 

how do you know how far down they swayed? You said In Your response In that we can't see the bottom.

We can't, but we can see that the elements that are swaying are the single columns at the top. There's plenty of videos on youtube that show good close-up views.

236 structural steel pieces found making each one aproxx 225 feet Long. Show me any evidence of this in the photo record.

And then explain where the steel for the Other building went.

I don't know why you think this number is significant. The team retained steel that looked like it might have damage or deformation that would be relevant to an investigation. They pulled something like half a million tons of debris out of ground zero and carted it off to Fresh Kills. What has given you this idea that somehow they didn't find any debris of the core? How would that even be possible?

Originally posted by Another_Nut

1. They resisted the horizontal loads during the swaying. Therefore saying it was the horizontal loads that brought it down is flawed.

1. They resisted the horiontal loads during the swaying, yes, for a matter of seconds. Above posters are correct that the 'core' portion of the structure was never designed to stand independently of the perimeter columns and floors. There's really no way that the spire could have remained upright for any length of time without bracing to keep it from buckling.

I am not sure if the core was not able to stand alone without floors or perimeter columns. I never seen any proof of this claim. They may have not been designed to do so but that does not mean they can't.

An aspect that seems to be overseen here is the damage that the rest of the collapse caused at the base. When a lot of mass all tries to occupy the same place at once, there will be a lot of forces in all directions. The core columns were only designed for vertical forces, so any horizontal displacement at the base would severely decrease the stability of the core columns.

reply to post by exponent


When steel welds fail it's not the actual weld that fails but the steel close to it, the heat effected zone, do you have any evidence of this?

Can you explain why the 1" and 5/8" inch bolts didn't fail when the trusses put a pulling force on them? How did they not fail if there was enough force to cause the much more massive columns to fail?

reply to post by ANOK


Explanation #5684:

The columns also had to carry the load of all floors above them. Pulling trusses caused a small displacement, Euler buckling did the rest. All this in combination with the increased load due to failed columns and the remaining columns being weakened by the heat of the fire.

Singling out just a single aspect and shouting "thats impossible" is fallacious.

Originally posted by ANOK

The object with the most mass will always receive the least damage, speed makes no difference to that fact. Increase the speed you increase the force felt by BOTH objects, so the damage will increase for BOTH objects.

You have stated that before and it has been pointed out to you before that it is false.

Any number of examples can show it is not true. If I shoot a bullet through a 2mm steel plate the deformation of the bullet and the hole in the plate will be just the same regardless of whether the plate is a square meter or 100 square meters. Similarly stone and plate glass window springs to mind.

Originally posted by DrEugeneFixer

Originally posted by Another_Nut

1. They resisted the horizontal loads during the swaying. Therefore saying it was the horizontal loads that brought it down is flawed.

1. They resisted the horiontal loads during the swaying, yes, for a matter of seconds. Above posters are correct that the 'core' portion of the structure was never designed to stand independently of the perimeter columns and floors. There's really no way that the spire could have remained upright for any length of time without bracing to keep it from buckling.

I dont call 15-30 seconds (depending on which core) as a "matter of seconds" especially after they survived the stress's invoked in the collapse and swaying for that time.

take a look at that 13meg photo.
Tower 1 core columns were sheered off near the top of the debris.notice the halo of absent columns around the core.
Notice the length of the columns , the sparsness and the straightness. And remember that a good weld is just as likely to fail as any other spot. These columns should have bent. Not broke. And even if they did break at weak spots ,to say every weld was a weak spot is a weak defense.

Notice tower 2 is also devoide of core columns and it had a 40 or so floor spire.

What I suggest we are seeing is core columns from the top of the towers . Not the spires.

Originally posted by Another_Nut

I dont call 15-30 seconds (depending on which core) as a "matter of seconds" especially after they survived the stress's invoked in the collapse and swaying for that time.

Well, you can't call it a matter of minutes or hours.

What exactly should we have expected to see?

Originally posted by Alfie1

You have stated that before and it has been pointed out to you before that it is false.

Any number of examples can show it is not true. If I shoot a bullet through a 2mm steel plate the deformation of the bullet and the hole in the plate will be just the same regardless of whether the plate is a square meter or 100 square meters. Similarly stone and plate glass window springs to mind.

Your analogy does not make what I stated incorrect. The mass of the objects colliding only matters at the point of the collision, not the whole object, so yes a bullet will make the same damage whatever the square area of the plate is. Make the plate thicker though, and you increase the mass where the bullet strikes, and you will get the same damage to the bullet, but the steel plates damage would decrease. Increase the velocity of the bullet, and you increase the force, thus the damage, to the bullet and the steel plate.

See it's not me who doesn't know physics, it's you not understanding what is being said without every single detail explained to you. A person who understands physics would understand it's not the whole mass of the object, but the parts that collide that matter.

Mass doesn't mean the weight of the object, but the density of the molecules.

Mass versus weight

If you don't believe me then educate yourself...

www.fearofphysics.com...

The object with the least mass will always be more effected by the collision than the object with the most mass. Because according to Newtons 3rd law there is ALWAYS an equal and opposite reaction. If you increase the velocity you increase the forces on BOTH objects. Regardless of your analogies, this is fact.

Originally posted by -PLB-
The columns also had to carry the load of all floors above them. Pulling trusses caused a small displacement, Euler buckling did the rest. All this in combination with the increased load due to failed columns and the remaining columns being weakened by the heat of the fire.

Singling out just a single aspect and shouting "thats impossible" is fallacious.

That doesn't explain anything.

You first need to explain how sagging trusses put a pulling force on the columns in the first place. Until you do that then anything else you say about the collapse is irrelevant.

What increased load? There was no increased load the building could not withstand. Steel has a very high weight to strength ratio which means it can hold much more weight than itself. When steel is welded and bolted in a triangular design (trusses and braced columns) it makes a very strong structure than can hold much more weight than itself. It will not fall apart under it's own weight. If a giant could have lifted the tower he could have thrown it around, and it would still stay in one piece (the steel frame that is).

How did the trusses put a pulling force on the columns in the first place? How did the 1" and 5/8" bolts not fail first? That is what you need to explain.

And no it's not catenary action.

Originally posted by ANOK

Originally posted by -PLB-
The columns also had to carry the load of all floors above them. Pulling trusses caused a small displacement, Euler buckling did the rest. All this in combination with the increased load due to failed columns and the remaining columns being weakened by the heat of the fire.

Singling out just a single aspect and shouting "thats impossible" is fallacious.

That doesn't explain anything.

You first need to explain how sagging trusses put a pulling force on the columns in the first place. Until you do that then anything else you say about the collapse is irrelevant.

Sure: www.sciencedirect.com...

This will be the fifth time you've refused to read this I think. Maybe sixth.

What increased load? There was no increased load the building could not withstand. Steel has a very high weight to strength ratio which means it can hold much more weight than itself. When steel is welded and bolted in a triangular design (trusses and braced columns) it makes a very strong structure than can hold much more weight than itself. It will not fall apart under it's own weight. If a giant could have lifted the tower he could have thrown it around, and it would still stay in one piece (the steel frame that is).

This is a particularly hilarious statement and I am going to save this to my quotes file because it shows complete ignorance of the construction of the building. Could you give me a list of the braced columns in the building and show with some form of mathematics how they can survive a giant throwing the building around. Thanks!

How did the trusses put a pulling force on the columns in the first place? How did the 1" and 5/8" bolts not fail first? That is what you need to explain.

And no it's not catenary action.

The pulling force is called tension. The bolts did not all fail as the individual forces were relatively low (a few tons).

reply to post by ANOK


You are denying both mathematical models and experimental data concerning trusses causing a pull in force.You really seem to be one of a very small group of people who does not understand this but still is under the illusion they do. You are denying reality. Same with gravity being an external force. You Google some sites that use a system where gravity is an internal force, but it changes nothing to your understanding of physics. You just fail to understand how to determine when a force is external and when it is internal. You fail at the very basics and your understanding of physics consist of Google searches. I bet you have never even solved an actual collage level physics problem. Tell me if I am wrong.


I can't help that you don't understand this. Just like I can't help that you don't understand that gravity is an external force in a building collapse. All I can do is explain it and point out your understanding of physics is flawed. Both of which I have done in many occasions. I also gave you a link to the Nasa site, a source which in my opinion has at least some authority. You flat out ignore it. Maybe it does not help you but it may help others who are pondering with the same questions.

Originally posted by DrEugeneFixer

Originally posted by Another_Nut

I dont call 15-30 seconds (depending on which core) as a "matter of seconds" especially after they survived the stress's invoked in the collapse and swaying for that time.

Well, you can't call it a matter of minutes or hours.

What exactly should we have expected to see?

Would you call a 15-30 minutes a matter of minutes? Or 8-10 hours a matter of hours? Or 150-180 days a matter of days?

To be honest im not sure they should have fallen at all. The lower columns were about 5 feet x 3 feet. That is bigger than the utility poles here and the can easily stand 6 stories.

Originally posted by ANOK

Originally posted by Alfie1

You have stated that before and it has been pointed out to you before that it is false.

Any number of examples can show it is not true. If I shoot a bullet through a 2mm steel plate the deformation of the bullet and the hole in the plate will be just the same regardless of whether the plate is a square meter or 100 square meters. Similarly stone and plate glass window springs to mind.

Your analogy does not make what I stated incorrect. The mass of the objects colliding only matters at the point of the collision, not the whole object, so yes a bullet will make the same damage whatever the square area of the plate is. Make the plate thicker though, and you increase the mass where the bullet strikes, and you will get the same damage to the bullet, but the steel plates damage would decrease. Increase the velocity of the bullet, and you increase the force, thus the damage, to the bullet and the steel plate.

See it's not me who doesn't know physics, it's you not understanding what is being said without every single detail explained to you. A person who understands physics would understand it's not the whole mass of the object, but the parts that collide that matter.

Mass doesn't mean the weight of the object, but the density of the molecules.

Mass versus weight

If you don't believe me then educate yourself...

www.fearofphysics.com...

The object with the least mass will always be more effected by the collision than the object with the most mass. Because according to Newtons 3rd law there is ALWAYS an equal and opposite reaction. If you increase the velocity you increase the forces on BOTH objects. Regardless of your analogies, this is fact.

edit on 12/15/2012 by ANOK because: (no reason given)

ANOK, you just seem to be trying to patch up an untenable theory that you have made up yourself

If you increase the thickness of the steel plate the exact same position applies. The plate will be damaged and the bullet will be deformed in just the same way if the plate is 1 foot square or 1 mile square.

reply to post by Alfie1


I still dont know what this has to do with the spire.

the columns were heavily braced until at least the 60th floor.

Here's a quick rundown of what I think.

Collapse was initiated by the breaking apart of the concrete floors ,which were acting as a brace for the trusses,from impact zone down. Once the concrete was gone the tower tops(read above impact zone) free fell to the ground

Leaving the spires. Stubbornly refusing fall. Now post collapse what physics do you think brought the spires straight down?
.

Originally posted by Another_Nut
reply to post by Alfie1
Now post collapse what physics do you think brought the spires straight down?
.

Check out Euler's column buckling equations.Link

parse it out and what you'll discover is that if you double the unbraced-length of a column, that column's ability to carry a load is reduced not to 1/2, but to 1/4 of it's former capacity. Triple the length of a column, and its load bearing capacity is reduced not to 1/3 of its former value, but to 1/9 of that capacity. In other words, the critical load of a column is related inversely to the square of the unbraced-length of the column.

while the perimeter wall stood, the unbraced length of columns in the core would have been the distance between floors, which is 12'6" if I recall correctly. Once the perimeter walls and floors were removed, the unbraced-length of the columns effectively shoots up to 400 feet or more. so, if the unbraced length changes by a factor of 10, the critical load on those columns will be changed by a factor of 1/100!

So the columns of the core, once removed from the context of the bracing provided by the perimeter walls and truss/floors, was only capable of bearing 1% of its former critical load without buckling!

Buckling failure seems inevitable, given this info.

And another thing. You said that the columns were heavily braced, at least to the 60th floor. Were you speaking of the bracing provided by the perimeter columns, through the floor trusses and concrete?

reply to post by Another_Nut


It didn't exactly fell straight down. Some parts fell over like trees (1), other parts collapsed after they started to topple over (2).

Originally posted by -PLB-
reply to post by ANOK

 

You are denying both mathematical models and experimental data concerning trusses causing a pull in force.

You need to show me those models mate. I have yet to see one in over eight years, and how many times have I mentioned this?

Trusses can cause a pulling force, trusses SAGGING from heat is a whole other matter.

There is no way a light-weight sagging truss can put a pulling force on more massive columns that had always held them up. How does the truss sagging put any more force on the columns then they already did? Again no it's not catenary action, that is only relevant to rigid objects like chains and cables, not SAGGING trusses.

The columns could have held the floor assembly many time over. The core and the trusses were designed to hold a lot more weight than they weighed themselves. The trusses were far more lighter than the columns. You always ignore FoS.

I know I have explained this over and over but it goes in one ear and out the other. When steel heats up it expands. The trusses were pinned between columns, they would have been unable to expand outwards so the expansion is taken up in sagging. It has nothing to do with load. If the trusses couldn't push out they would also not be able to pull in so they SAG. The sagging does not put any more force on the columns, and even IF it did the columns would still not have been effected. The trusses simply do not weigh enough.

I'd love to see a demonstration of that happening. The closest I've come to a demonstration of catenary action is this....



Notice that load bearing columns were removed, extra weight was added to the floor, the floor sagged from the weight not heat so was still rigid, but it still didn't put enough of a pulling force to cause the walls they were attached to to be pulled in. WTC had no extra weight added, no load bearing columns removed and the trusses were sagging.