Outside energy had to be introduced for the twin towers to collapse the way they did

Originally posted by ANOK

Originally posted by wmd_2008

You need to calculate the FoS of all the connections, combined, not the floor slab.

Remember you claim the connections failed, not the floors themselves?

The standard FOS used for structural fixings/connections is 3:1 so guess what the 3000 tons I worked out was for ALL the connections as they hold up the mass of the floorslab

I asked if psik was following it I should have asked you have IT SEEMS!!!!

Originally posted by psikeyhackr

Originally posted by wmd_2008Well why dont you use some common sense what data do we have ?

Well you have heard of FACTOR OF SAFETY so lets help you again as construction is not your strong point!

Mass of a floorslab is just over 700 tons (UK TONS) put another 100 tons on for trusses and decking steel (it's probably less than that) so thats 800 tons.

Most engineers are happy with a 3:1 FOS so that's 3 x 800 = 2400 tons
( hope this is not to complicated for you psik)

Lets round that up to 3000 tons so that would give you a good indication of what the connections would support.

OVER to you now LETS see you do some number crunching if you can that is!!!

Here is the calculation for the weight of the slab.

(((206*206)-(136*86))*(4.333/12)*110)/2000 = 610.48 short tons

The pans were corrugated so the average thickness is 4.333 inches. The concrete was 110 lb/cu ft.

I have never seen data on the weight of all of the trusses and floor pans. So you do whatever inaccurate calculations you want. I have seen the weight per square foot that the floors were supposed to hold but I don't recall what it was.

So you do whatever inaccurate calculations you want.

I could not care less. The distribution of steel down the building which most people do not talk about is more important than the floor pancaking delusion that is constantly promoted. The Potential Energy of the building cannot even be accurately computed without the distributions of steel and concrete. Curious how such a simple but obvious calculation is not discussed by people constantly talking about MATHEMATICS.

psik

edit on 17-11-2011 by psikeyhackr because: (no reason given)

Well I can't understand why you took out the area of the floorslab for the core or did the people float to the lifts toilets and stairwells in that area?

If we know the floorslab weight we can work out the approximate impact loads and if the connections with their FOS could survive an impact.

Originally posted by wmd_2008

Originally posted by psikeyhackr

Originally posted by wmd_2008Well why dont you use some common sense what data do we have ?

Well you have heard of FACTOR OF SAFETY so lets help you again as construction is not your strong point!

Mass of a floorslab is just over 700 tons (UK TONS) put another 100 tons on for trusses and decking steel (it's probably less than that) so thats 800 tons.

Most engineers are happy with a 3:1 FOS so that's 3 x 800 = 2400 tons
( hope this is not to complicated for you psik)

Lets round that up to 3000 tons so that would give you a good indication of what the connections would support.

OVER to you now LETS see you do some number crunching if you can that is!!!

Here is the calculation for the weight of the slab.

(((206*206)-(136*86))*(4.333/12)*110)/2000 = 610.48 short tons

The pans were corrugated so the average thickness is 4.333 inches. The concrete was 110 lb/cu ft.

I have never seen data on the weight of all of the trusses and floor pans. So you do whatever inaccurate calculations you want. I have seen the weight per square foot that the floors were supposed to hold but I don't recall what it was.

So you do whatever inaccurate calculations you want.

I could not care less. The distribution of steel down the building which most people do not talk about is more important than the floor pancaking delusion that is constantly promoted. The Potential Energy of the building cannot even be accurately computed without the distributions of steel and concrete. Curious how such a simple but obvious calculation is not discussed by people constantly talking about MATHEMATICS.

psik

edit on 17-11-2011 by psikeyhackr because: (no reason given)

Well I can't understand why you took out the area of the floorslab for the core or did the people float to the lifts toilets and stairwells in that area?

If we know the floorslab weight we can work out the approximate impact loads and if the connections with their FOS could survive an impact.

Only an IDIOT would not have taken out the core area. The concrete slabs used in the core were 5 inches thick and used the 150 lb/cu ft concrete plus the elevator shafts did not include floor. The core would have been a higher traffic area with everyone having to use the elevators and go to the bathrooms. Plus the floors in the core were not supported by the truss connections that you make a such big deal about. You are contradicting yourself in talking about floors pancaking if you include the core to apply to the trusses. But including the core would also mean explaining the columns and horizontal beams and including that mass of steel.

In fact if you include the core wouldn't have to ignore all of the truss connections that connected the outer floor slab to the core.

No wonder you can't figure out what is going on.

You are demonstrating why this so called debate is so STUPID and yet not resolved after TEN YEARS.

psik

Originally posted by wmd_2008
The standard FOS used for structural fixings/connections is 3:1 so guess what the 3000 tons I worked out was for ALL the connections as they hold up the mass of the floorslab

But that is not even how it's figured anyway. It's not simply weight x the FoS.

FoS is the structural capacity above normal expected, or actual loads. Basically they take the maximum they think the component can withstand over its lifetime, and then the safety factor is how much more load it can withstand above that, not above its own base weight. FoS x the weight of the floor is not the FoS of the floor. It's something like, FoS = failure load divided by design load -1, if I remember correctly.

Also x3 is not the standard, x2 is usually the minimum for any component. Fos is not just a fixed number. A single connection might start with an FoS of x3, but put two together and that increases.

All components have an FoS, and you need to figure out how much pressure the whole floor system could withstand before failure. Not the weight of the floor x3.

I asked if psik was following it I should have asked you have IT SEEMS!!!!

Hmm is English not your first language, I have no idea what you just said?

Originally posted by ANOK

Originally posted by wmd_2008
The standard FOS used for structural fixings/connections is 3:1 so guess what the 3000 tons I worked out was for ALL the connections as they hold up the mass of the floorslab

But that is not even how it's figured anyway. It's not simply weight x the FoS.

FoS is the structural capacity above normal expected, or actual loads. Basically they take the maximum they think the component can withstand over its lifetime, and then the safety factor is how much more load it can withstand above that, not above its own base weight. FoS x the weight of the floor is not the FoS of the floor. It's something like, FoS = failure load divided by design load -1, if I remember correctly.

Also x3 is not the standard, x2 is usually the minimum for any component. Fos is not just a fixed number. A single connection might start with an FoS of x3, but put two together and that increases.

All components have an FoS, and you need to figure out how much pressure the whole floor system could withstand before failure. Not the weight of the floor x3.

I asked if psik was following it I should have asked you have IT SEEMS!!!!

Hmm is English not your first language, I have no idea what you just said?

edit on 11/18/2011 by ANOK because: typo

WHAT holds the floorslab trusses in position ANOK ? yes the connections if the weld fails round the angle seat the connection has failed, if a leg shears off the angle seat the connection fails if the bolts shear the connection fails.

Give you a little example in the UK for metal structural fixings engineers look for 3:1 FOS for plastic plug and screw type fixings 7:1 for obvious reasons!

I did a test for an engineer on a veranda/balcony application, he had worked out a working load of 1.5kn per fixing (150kg) he wanted them tested to 5kn (500kg) nice and easy to read on the dial rather than taking it to 4.5kn.

Now since we have pictures of sheared angle seats ! and column trees a few floors high after the collapse and the spire with NO floors attached what do you think failed?

I did a quick exercise to show an approximate load that would keep most engineers happy re the floorslab based on the mass of the slab and the 3:1 safety factor NOW SINCE you always want to avoid it why dont you or psik work out a possible impact load for just one slab falling 12ft 3.6 mtrs YOU do it then you cant say I fudged the figs.

If you are so confident we are wrong then whats the problem?

I REFER you back to the thread title

"Outside energy had to be introduced for the twin towers to collapse the way they did"

That was the aircraft, the structural damage and the fires, GRAVITY did the rest!

reply to post by psikeyhackr


Funny psik you always claim you can't get/find any info yet when pushed you seem to be able to find it.
Did the concrete in the core area fall or did it magically float during the collapse can you provide a link to the 150lb cft figure out of interest. I have only seen 115 for the floors anything heavier was for the service floors or foundations so maybe your figs are wrong?

Originally posted by wmd_2008
reply to post by psikeyhackr

 

Funny psik you always claim you can't get/find any info yet when pushed you seem to be able to find it.
Did the concrete in the core area fall or did it magically float during the collapse can you provide a link to the 150lb cft figure out of interest. I have only seen 115 for the floors anything heavier was for the service floors or foundations so maybe your figs are wrong?

What are you claiming that I found? Sources from before 9/11 say there were 425,000 cubic yards of concrete in both towers. That does not specify how much was 150 lb versus 110 lb. There were only 84 standard desin floors in each tower. Some sources indicate there was a concrete box around the core at least part way up the building. So my question about tons of steel and tons of concrete on each and every level still stands.

It isn't my fault that you try to make silly calculations regarding the floor slab while pretending the core is not there but then want to talk about tuss connections which had to attach to the core.

That is pretty damn funny.

psik

Originally posted by wmd_2008
WHAT holds the floorslab trusses in position ANOK ? yes the connections if the weld fails round the angle seat the connection has failed, if a leg shears off the angle seat the connection fails if the bolts shear the connection fails.

What has that got to do with your failure to understand what the FoS is? Why did you insist on using the floor slab to figure out the FoS, when you know the connections are what holds the floors?

The concrete is the weakest part of the construction. You don't even consider the steel pans they sat in, where did they all go? Do you have any pics of those steel pans still in one piece?

Give you a little example in the UK for metal structural fixings engineers look for 3:1 FOS for plastic plug and screw type fixings 7:1 for obvious reasons!

Again so what? Components are designed for the job they are required to do. Truss seat connections would be designed to hold the floors. Are you trying to say the WTC design was inadequate now, they chose the wrong FoS? You don't even know what the FoS was, x3 is a complete guess, and you didn't mention if that was a single connection or all of them combined.

I did a test for an engineer on a veranda/balcony application, he had worked out a working load of 1.5kn per fixing (150kg) he wanted them tested to 5kn (500kg) nice and easy to read on the dial rather than taking it to 4.5kn.

Again so what? How does that explain your misunderstanding of how the FoS is calculated?

Now since we have pictures of sheared angle seats ! and column trees a few floors high after the collapse and the spire with NO floors attached what do you think failed?

Pictures do not prove when the event happened, or what caused it. Problem is you hypothesis simply wouldn't work, even if all the truss connections simply sheared allowing floors to drop there would still be resistance as all the mass builds up, but it didn't build up barbecue it was all ejected during the collapse.

Also again your hypotheses does not address the collapse of the core. It also doesn't explain why the core falls before the floors did.

I did a quick exercise to show an approximate load that would keep most engineers happy re the floorslab based on the mass of the slab and the 3:1 safety factor NOW SINCE you always want to avoid it why dont you or psik work out a possible impact load for just one slab falling 12ft 3.6 mtrs YOU do it then you cant say I fudged the figs.

If you are so confident we are wrong then whats the problem?

Why do you keep claiming I avoid this, did you read my last post to you?

The problem is, as I explained in my last post, FoS is not measured like that. 3x the weight of the floors slab is not the FoS, not even close. Each separate component has an FoS, if one truss connector has an FoS of x3 then 100 of them would have an FoS far higher than x3.

I REFER you back to the thread title

"Outside energy had to be introduced for the twin towers to collapse the way they did"

That was the aircraft, the structural damage and the fires, GRAVITY did the rest!

Wrong. The aircraft damage did not cause the collapses, according to the NIST report trusses sagged from heat pulling in columns. We reject that claim because we know fire can not get steel hot enough in an hour to cause failure of steel, and sagging trusses can not also create a pulling force on larger columns. WTC 7 was not hit by an aircraft.

This is a good example of how you OSers ignore facts. I showed how you are wrong about the FoS, yet you continue to make your false claims. Intellectual dishonesty.

Originally posted by psikeyhackr

That is pretty damn funny.

You can say that again mate.

reply to post by ANOK

....if one truss connector has an FoS of x3 then 100 of them would have an FoS far higher than x3

The designers consider the assembly, acting as a unit, in its final application not each individual nail and spot of glue.

Exactly, hooper.

FOS and DCR (demand-to-capacity) tend to be used interchangeably even though they're not, with the reciprocal of DCR being the quantity people are usually talking about when they say FOS. Each component experiences a particular demand and has a specific capacity. Subassemblies of individual components and the assembly as a whole have some DCR.

Typically, if there is a FOS associated with each connection, that connection is nominally subjected to a share of stress amongst the components so as to stay within desired FOS. If one bolt has FOS of 3 against a given load or stress (and that's the only way FOS makes sense), then adding more bolts will increase the strength of the assembly and therefore the FOS - for a given load. Put that much more load on, and the FOS is back where it was.

Now, look at those ****ing 5/8" lawnmower engine bolts serving as part of the floor connections all the way up a quarter mile high skyscraper and tell me what the weak link in the assembly is.

Besides, DCR in structural engineering is primarily a static consideration. Dynamic loading is an entirely different matter. If a steel column has the capacity to support 1.99x a given load, and the load is merely brought into contact with the end of the column and released, the elastic limit of the column will be reached and plastic deformation commence. That's not dropping the load, that's letting it touch the unloaded column and then releasing it.

Originally posted by hooper
The designers consider the assembly, acting as a unit, in its final application not each individual nail and spot of glue.

did I mention glue lol.

I said every competent, meaning every connection, truss, beam, column etc.

Laugh on, you are again just proving your ignorance. Can't you guys just admit you're wrong for once? Enough with the petty arguing over every point raised.

Applying Safety Factors

Bolted connections are sized for safety.

No bolted connection would be designed with the intention of having it break, so engineers and mechanics apply safety factors in determining the proper sizes of bolts and nuts to use.
The maximum load a bolt would be designed to carry is known as the "proof load," which is about 92 percent of the yield strength. By keeping the expected load below this point, it is certain that the bolt will not lose strength by permanently stretching. In practice, safety factors more stringent than the proof load are used for most connection designs. For example, a safety factor of 2 would require that the expected load on the connection be less than half of the material's yield strength.

www.ehow.com...

Even bolts have an FoS.

reply to post by ANOK


Well, you certainly know how to cut and paste links, too bad you have no idea how things are actually designed and built. Safety is considered as it applies to the final assembly. How things act as a unit. Not to each and every nail and spot of glue.

But telling you this is pretty much useless. If you understood how structures worked then you wouldn't be out seeking the "truth" about how the towers collapsed on 9/11/2001. It would be as self-evident to you as it is to the rest of the world.

Originally posted by IrishWristwatch

Besides, DCR in structural engineering is primarily a static consideration. Dynamic loading is an entirely different matter. If a steel column has the capacity to support 1.99x a given load, and the load is merely brought into contact with the end of the column and released, the elastic limit of the column will be reached and plastic deformation commence. That's not dropping the load, that's letting it touch the unloaded column and then releasing it.

And then equal opposite reaction, and momentum conservation, comes into play.

All colliding objects put an equal force on each other. So your falling floors will experience the same force as the floors they were colliding with. So any deformation will effect both the falling, and static floors. The connections would have failed on the falling floors, the same way as the static floors. So the falling floors simply could not stay in one piece while crushing all the static floors. 15 falling floors would be gone long before they could cause the 95 floors to collapse.

But this is all hypothetical anyway because the collapses did not happen the way you claim...



Notice the bottom of the falling block of floors? Those lower floors are being crushed before the bottom started to collapse. That alone prove my point.

reply to post by ANOK

So your falling floors will experience the same force as the floors they were colliding with. So any deformation will effect both the falling, and static floors.

Wrong.

Again.

Same force does not = same effect because a falling floor does not = a fixed floor.

Originally posted by ANOK

Originally posted by IrishWristwatch

Besides, DCR in structural engineering is primarily a static consideration. Dynamic loading is an entirely different matter. If a steel column has the capacity to support 1.99x a given load, and the load is merely brought into contact with the end of the column and released, the elastic limit of the column will be reached and plastic deformation commence. That's not dropping the load, that's letting it touch the unloaded column and then releasing it.

And then equal opposite reaction, and momentum conservation, comes into play.

Absolutely true.

All colliding objects put an equal force on each other. So your falling floors will experience the same force as the floors they were colliding with. So any deformation will effect both the falling, and static floors.

Absolutely true. (Edit: with one difference - the floor below has self load and the load above it)

The connections would have failed on the falling floors, the same way as the static floors.

Well, if a floor is falling, one can safely assume the connections for that floor have already failed.

So the falling floors simply could not stay in one piece while crushing all the static floors.

I'm sure that's quite true.

15 falling floors would be gone long before they could cause the 95 floors to collapse.

By "gone" do you mean disappeared? Vanished? If not, the debris still has the same mass as the intact structure from which it came, and if it's moving, it has momentum. Granted, the peak impulse from an intact body in collision is higher than the same body impacting as fragments. but the overall momentum change to bring the fragments to rest is exactly the same as the intact body and the static load it imposes also the same.

But this is all hypothetical anyway because the collapses did not happen the way you claim...

What is it, pray tell, that I claim?

Originally posted by ANOK
Notice the bottom of the falling block of floors? Those lower floors are being crushed before the bottom started to collapse. That alone prove my point.

I guess you seem to think I'm a rigid blockhead. I'm not. I know damn well the top experienced a faster rate of crush* than the bottom immediately after initiation.

* I also know that "crush" can be perceived as a loaded term. A more neutral term would be "disintegrate".

It might be useful to establish who here believes the perimeters and one floor diaphragm could support the STATIC mass of 10-15 stories as rubble. A dumpster in the sky.

Interestingly enough, the best area of study to examine this question is the work associated with grain silos.

Originally posted by IrishWristwatch

I guess you seem to think I'm a rigid blockhead. I'm not. I know damn well the top experienced a faster rate of crush* than the bottom immediately after initiation.

* I also know that "crush" can be perceived as a loaded term. A more neutral term would be "disintegrate".

Use whatever term you're happy with, its just semantics. Deformation is a better term. I like crushed because it's more generic term that covers deformation and disintegration. It's not a deal breaker lol.

So if the falling floors were being 'disintegrated', then how did they have the energy and mass to continue 'disintegrating' 95 more floors?

'Disintegration' means Ke was being lost, mass was being lost. Ke converting to heat, sound and deformation means the energy to continue 'crushing' more floors is reduce. Once that Ke is gone its gone, no more energy to keep 'disintegrating' more floors. The only way to regain that Ke is another outside energy source feeding it, something that was not investigated for.

Originally posted by ANOK
But this is all hypothetical anyway because the collapses did not happen the way you claim...

I also am amused when someone trots out something inferior to my own work to prove a point I already know.

Here are some things I made. Not someone else. Me.





And that's a very small sample of megs of stuff just like it. I never bothered with the "compression" aspect your graphic stresses because it was immediately obvious at first glance. No lines need to be drawn to see it.