A Question for Heiwa - WTC Safety Factors

[Architect]

I concur and, like yourself, make similar points in the "gravity" thread. What I'm trying to establish here is the basis for Heiwa's "FoS>3" claim and how he responds to the NIST data showing this to be incorrect.

 

[Architect]

Well if this is not the ultimate compliment I don't know what is. Heiwa's very own forum. I hope you have not bitten off more than you can chew Architect.

bill smith wrote:
<quoted text>
I've ben following the arguments over there and nobody has debunked any statement that Heiwa has made. Otherwise they woud all be all over him like white on rice just as you see the jackals here jump on wounded prey. That hasn't happened over there. The best they have managed to do is the pizza boxes the sponge and the bed.
The Architect whiner should do what Heiwa told him to do and read the papers Heiwa has published with all relevent calculations already in and for which he has provided links..
​

Bill, You must be terribly disappointed with Heiwa's attempts on this thread thus far.
​

 

[Heiwa]

A second massive error that Heiwa makes in his statement that "a smaller portion of the building can never crush down a bigger section" is to assume - incorrectly - that you can average the stress & strain energy over the entire structure. Doing this ignores (& eliminates) stress & strain energy concentrations that are key to progressive collapse.

tom

I would say that this is the error of NIST, Bazant, Seffen & Co. They apparently assume in their 1-D models some average stress/strain energy applied over 4000 m² WTC 1 cross area of structure shredding only the lower contact part of it, the damaged elements of which are then compressed into rubble, etc. Upper part C remains intact. Fantasy of course - and nothing to do with structural damage analysis. If you read my article you will find that only 0.05 kWh/ton rubble is apparently used to crush down WTC1 as per NIST & Co:s model. That is much too little. To shread, e.g. a car you need 36.7 kWh/ton or 734 times more energy.

You are 100% right that you have to study the 'stress/strain energy concentrations' and what they are up to, i.e. what happens where elements of upper part C contact lower part A and vice versa. The result is always only local failures and ... collapse/crush down/destruction arrest.

 

[KTB]

Hey heiwa, how about you just answer the question about "FoS>3"? You are getting tedious.

 

[Architect]

I would say that this is the error of NIST, Bazant, Seffen & Co. They apparently assume in their 1-D models some average stress/strain energy applied over 4000 m² WTC 1 cross area of structure shredding only the lower contact part of it, the damaged elements of which are then compressed into rubble, etc. Upper part C remains intact. Fantasy of course - and nothing to do with structural damage analysis. If you read my article you will find that only 0.05 kWh/ton rubble is apparently used to crush down WTC1 as per NIST & Co:s model. That is much too little. To shread, e.g. a car you need 36.7 kWh/ton or 734 times more energy.

<snip>

Heiwa

This is a thread specifically for your to support your claim that the factor of safety found at the towers was greater than 300% ("FoS>3"). A copy of your post, and my detailed response querying the veracity of your claim, form the OP. Should you wish to discuss gravity collapse models then you should go to that thread.

Now, are you able to defend your own proposition regarding safety factors with, for example, calculations or detailed references to codes? Or, to be quite frank, did you just make the figure up? And if it's the former, can you please explain to me, in detail, where my response to your claim is in error.

 

[Heiwa]

Hey heiwa, how about you just answer the question about "FoS>3"? You are getting tedious.

Already answered several times above and in other threads. You missed THAT?

 

[Dave Rogers]

Already answered several times above and in other threads. You missed THAT?

Heiwa has not, of course, done so. There is no post where he gives a source or calculations to justify his bare assertion that the WTC towers were built with a FoS greater than 3. This will be demonstrated by the fact that he will be unable, in reply to this post, to link to any such post, but will instead at most simply repeat his assertions.

Dave

 

[KTB]

Already answered several times above and in other threads. You missed THAT?

The sad thing is that you actually believe this yourself. Well good luck with your calculations, you really rock.

 

[Heiwa]

Heiwa has not, of course, done so. There is no post where he gives a source or calculations to justify his bare assertion that the WTC towers were built with a FoS greater than 3. This will be demonstrated by the fact that he will be unable, in reply to this post, to link to any such post, but will instead at most simply repeat his assertions.

Dave

Maybe you misunderstood my reply? Regardless, various FoS of the WTC structure components is of no importance as long as it is accepted that upper part C was built similar to lower part A, incl. FoS of elements.
The basic mistake of NIST and Bazant & Co when analyzing the destruction is that they treat the problem as a mechanical one of solids, where you can assume parts and elements to be rigid, i.e. they do no deform. In structural analysis evidently no part is rigid, as the whole purpose is to see how each non-rigid element deforms elastically and transmits the loads as forces and moments from one element to another. Structural damage analysis is the most advanced stage of structural analysis as then elements are deforming or have deformed plastically and/or failed and the whole layout of the structure under analysis change at every failure with associated modified load paths, etc.
It seems NIST and Bazant & Co have very limited experience of structural damage analysis or just simple structural analysis, as they introduce rigid elements and complete rigid parts in their models. As the rigid parts do not deform at all they evidently transmit forces without getting damaged. And then, e.g. FoS of elements inside this assumed rigid part bcomes of no interest to them.
Result? Horrendous conclusions that a small part of a structure (assumed rigid) can crush a bigger part of the same structure (assumed non-rigid) and similar; the small part (assumed rigid) accelerates through the big part, etc, etc. It is sad that NIST has adopted such stupid methods ... and the result is evident: to suit a misguided political agenda based on scientific nonsense.

It is quite funny to follow the supporters of this agenda here at JREF and their arguments. I have put most of the worst ones on ignore as they just repeat themselves and just study the more advanced ones. But it is the same nonsense, nevertheless.

 

[Dave Rogers]

Heiwa's responses to being caught in a lie:

(a) Claim he never said it.
(b) Admit he said it, but pretend it's true.
(c) Claim it doesn't matter.
(d) Accuse everyone else in the world of lying.

Basically, just like the small children he claims to be talking to.

Dave

 

[A W Smith]

Anders.

I see nowhere your worksheets or calculations proving a safety factor of 300% ("FoS>3").. You keep saying you have answered this but it is perfectly clear to all you have not. You have been caught in a lie. Your work is nothing more than false assertions and errors of omission.

Answer the op or concede.

 

[Architect]

Maybe you misunderstood my reply? Regardless, various FoS of the WTC structure components is of no importance as long as it is accepted that upper part C was built similar to lower part A, incl. FoS of elements.

Anders

You were the one who raised the issue of Factor of Safety as supporting evidence that the lower structure had sufficient integrity to restrain the overall collapse.

Having been asked to justify this statement, inasmuch as calculations of actual demand to capacity ratios are significantly less, you have claimed that the Factor fo Safety is "of no importance".

I assume that you realise how this appears. Either:

(a) The FoS is not relevant and you introduced spurious material in support of your argument, or

(b) You have been unable to support your claim.

Whichever it is, it doesn't look very good, does it? And if it's (a), then I think you have to retract the post you originally made on the subject.

So, which is it?

 

[Gravy]

The basic mistake of NIST and Bazant & Co when analyzing the destruction is that they treat the problem as a mechanical one of solids, where you can assume parts and elements to be rigid, i.e. they do no deform.

Guess what? Claiming something doesn't make it true.

It seems NIST and Bazant & Co have very limited experience of structural damage analysis or just simple structural analysis...

Says the guy who thinks the Twin Towers were analogous to pizza boxes and towers of lemons.

Why did you lie about the factor of safety?

 

[Heiwa]

Anders.

I see nowhere your worksheets or calculations proving a safety factor of 300% ("FoS>3").. You keep saying you have answered this but it is perfectly clear to all you have not. You have been caught in a lie. Your work is nothing more than false assertions and errors of omission.

Answer the op or concede.

I have answered that one several times, which is perfectly clear to me. See http://heiwaco.tripod.com/nist0.htm#3 . Just click and look. Scroll down to 5.3.

Any problem? It deals with the primary structure - the columns. Pretty strong - to say the least.

Redundancy is then provided by the spandrels. Remove 70% of the wall columns in the north wall, i.w.o. floors 93-98 and nothing really happens.

Reason? These columns were low stressed in the first place, FoS>5 w.r.t. static loads, and the load was just transmitted via the spandrels to the adjacent intact structure, incl. all the other walls.

Why are you so concerned about F.o.S.? You do not like my conclusion that upper part C can never crush lower part A? Or all observations that upper part C is destroyed by controlled demolition before part A suffers the same fate? Let's discuss those instead. They are more interesting.

Why does NIST invent a stupid theory that little part C can destroy big part A because PE>SE without any calculations of PE or SE? Why do Bazant & Co have to assume that part C is rigid while part A below is not in a 1-D model where a rigid line C compresses a non-rigid line A? These people seem to lack imagination. Can't they come up with cleverer propaganda?

It was not necessary. Any US person with relevant qualifications that queried the NIST/Bazant nonsense was quickly fired from his job! So the rest shuts up. No solidarity there. Lack of moral fibre throughout.

Except my hero Richard Gage and his team at http://AE911truth.org. Join them.

 

[A W Smith]

I have answered that one several times, which is perfectly clear to me. See http://heiwaco.tripod.com/nist0.htm#3 . Just click and look. Scroll down to 5.3.

Any problem? It deals with the primary structure - the columns. Pretty strong - to say the least.

Redundancy is then provided by the spandrels. Remove 70% of the wall columns in the north wall, i.w.o. floors 93-98 and nothing really happens.

Reason? These columns were low stressed in the first place, FoS>5 w.r.t. static loads, and the load was just transmitted via the spandrels to the adjacent intact structure, incl. all the other walls.

Why are you so concerned about F.o.S.? You do not like my conclusion that upper part C can never crush lower part A? Or all observations that upper part C is destroyed by controlled demolition before part A suffers the same fate? Let's discuss those instead. They are more interesting.

Why does NIST invent a stupid theory that little part C can destroy big part A because PE>SE without any calculations of PE or SE? Why do Bazant & Co have to assume that part C is rigid while part A below is not in a 1-D model where a rigid line C compresses a non-rigid line A? These people seem to lack imagination. Can't they come up with cleverer propaganda?

It was not necessary. Any US person with relevant qualifications that queried the NIST/Bazant nonsense was quickly fired from his job! So the rest shuts up. No solidarity there. Lack of moral fibre throughout.

Except my hero Richard Gage and his team at http://AE911truth.org. Join them.

5.3 Compressive Stresses in the primary Structure Columns - less than 1/3 of the Yield Stress
The mass above the walls at floors 94-98 is thus about 16 500 tons supported by 236 wall columns (total cross area 3.54 m²). Therefore each wall column on average supports 70 tons.
The compressive stress in the wall column at floors 94-98 with cross area 150 cm² is thus abt 467 kgs/cm² or 46 MPa or 18.8% of the yield stress (abt 248 MPa) of the steel.
NIST suggests that the static loads will be increased 35% in the East wall and 30% in the West wall (all 100% intact) due to load transfers just prior collapse, i.e. the compressive stresses in columns there becomes 62.1 and 59.8 MPa, which is still only 25% and 24% if the yield stress. Actually these are the increased stresses you would expect due to wind under hurricane conditions.
The mass above the core is also 16 500 tons supported by the 47 core columns with total area 2.1 m². On average each core column carries abt 351 tons so the average compression is 786 kgs/cm² or 78 MPa or 31.7% of yield. The outer core columns carry more mass and the outer corner core columns the most load, e.g. no. 501 with cross area 950 cm². It may carry as much as 750 tons.
The compressive stress in the no. 501 core column at floors 94-98 is thus abt 789 kgs/cm² or 78 MPa or 31.7% of the yield stress of the steel. It is assumed that the compressive stress in the other core columns is abt the same or less.
NIST suggests that the load in the core is reduced 20% just prior collapse, i.e. the stresses are reduced. However, some core columns may have been damaged in the initiation zone so in all probability the stresses in the remaining columns may have remained at 30% yield stress.
The reason why original the static stresses are higher in the core than in the perimeter walls is that the wall columns are also designed to absorb dynamic wind loads

and here in all its glory is your error of omission

http://en.wikipedia.org/wiki/Buckling

In engineering, buckling is a failure mode characterized by a sudden failure of a structural member subjected to high compressive stresses, where the actual compressive stress at the point of failure is less than the ultimate compressive stresses that the material is capable of withstanding. This mode of failure is also described as failure due to elastic instability. Mathematical analysis of buckling makes use of an axial load eccentricity that introduces a moment, which does not form part of the primary forces to which the member is subjected.

 

[Architect]

Let's play a game called "compare and contrast". First, Heiwa:

5.3 Compressive Stresses in the primary Structure Columns - less than 1/3 of the Yield Stress
The mass above the walls at floors 94-98 is thus about 16 500 tons supported by 236 wall columns (total cross area 3.54 m²). Therefore each wall column on average supports 70 tons.
The compressive stress in the wall column at floors 94-98 with cross area 150 cm² is thus abt 467 kgs/cm² or 46 MPa or 18.8% of the yield stress (abt 248 MPa) of the steel.
NIST suggests that the static loads will be increased 35% in the East wall and 30% in the West wall (all 100% intact) due to load transfers just prior collapse, i.e. the compressive stresses in columns there becomes 62.1 and 59.8 MPa, which is still only 25% and 24% if the yield stress. Actually these are the increased stresses you would expect due to wind under hurricane conditions.
The mass above the core is also 16 500 tons supported by the 47 core columns with total area 2.1 m². On average each core column carries abt 351 tons so the average compression is 786 kgs/cm² or 78 MPa or 31.7% of yield. The outer core columns carry more mass and the outer corner core columns the most load, e.g. no. 501 with cross area 950 cm². It may carry as much as 750 tons.
The compressive stress in the no. 501 core column at floors 94-98 is thus abt 789 kgs/cm² or 78 MPa or 31.7% of the yield stress of the steel. It is assumed that the compressive stress in the other core columns is abt the same or less.
NIST suggests that the load in the core is reduced 20% just prior collapse, i.e. the stresses are reduced. However, some core columns may have been damaged in the initiation zone so in all probability the stresses in the remaining columns may have remained at 30% yield stress.
The reason why original the static stresses are higher in the core than in the perimeter walls is that the wall columns are also designed to absorb dynamic wind loads

Now, the challenge put to Heiwa:

NIST tested the steel recovered from WTC (which in itself is of interest, as CTers usually claim it was all whisked away to China with unseemly haste). NIST NCS STAR 1-3D (http://www.fire.nist.gov/bfrlpubs/fire05/PDF/f05158.pdf) confirms a range of actual values:

- Core webs ranged from as low as 31.1 to 41.9 ksi, ie. 86 to 116% of specificed strength.

- Core flanges ranged from 32.4 to a high 53.4 ksi, ie. 90 to 146% of specified strength.

Setting to one side the 31.1 and 32.4 ksi results, inasmuch as a small proportion of columns below failure point are unlikely to lead to any wider problem, let's take the lower maximum of 116% specified value.

Now, the NIST Demand to Capacity Ratios (DCR) are based upon specified strengths and NIST themselves note that there is effectively spare capacity up to actual (but varying) yield point/strength.

Core columns in WTC typically had a Demand to Capacity Ratio (DCR) of 0.83, ie a safety factor of 1/0.83=1.20. Now let's assume assume that the steel has an additional 16% beyond minimum yield value. This would reduce the DCR to 1.16/.83=1.4.

In other words we could increase the loads in these areas by up to 40% before yield point was reached and plastic (permanent) deformation begins. Of course this figure has lots of variables - most of the steel webs did not have such a high yield factor, some areas had DCRs well in excess of 0.83, and so on.

What we don't do is then add any significant additional allowance for tensile strength because (a) yield failure is already occuring and (b) gravity loads will be compressive, not tensile.

As I frequently mention elsewhere on the forums, one thing we also have to appreciate is that the structure of WTC is complex; in addition to dead and live loads, it will be dealing with (for example) transverse and shear loadings from the wind. There will be a degree of torsion due to differential loading. And so on. We would therefore have to look at the exact steelwork design in considerable detail before we could determine a safety factor for each. That's why engineers earn a lot of cash, and why complex modelling software was developed.

Nevertheless it is clear that the actual capacity of the core is not going to be anything like 300% or 3:1 before irreversible damage and failure begin to occur.

But in any event the above calculations all assume an intact core, and we know from the various NIST studies and eyewitness evidence that the cores suffered damage - around a third. This will obviously have reduced loadbearing capacity still further, and a simple pro-rata reduction of (say) 30% is likely to be wrong because the damage is concentrated in localised areas and hence these areas will be susceptible to accelerated failure under loads.

Essentially, Heiwa's figures bear little resemblance to reality. Why might this be?

 

[Heiwa]

and here in all its glory is your error of omission

http://en.wikipedia.org/wiki/Buckling

Yes, but in the case of WTC columns the buckling stress exceeds the yield stress so the yield stress is the critical stress. Explained elsewhere is my paper. Pretty strong columns, to say the least.

Thanks for visiting my web site. There is plenty to learn there.

 

[Gravy]

Yes, but in the case of WTC columns the buckling stress exceeds the yield stress so the yield stress is the critical stress. Explained elsewhere is my paper. Pretty strong columns, to say the least.

In what engineering arena is "I made everything up" an acceptable response to thoughtful criticism?

 

[R.Mackey]

Imagineering.

 

[beachnut]

Yes, but in the case of WTC columns the buckling stress exceeds the yield stress so the yield stress is the critical stress. Explained elsewhere is my paper. Pretty strong columns, to say the least.

Thanks for visiting my web site. There is plenty to learn there.

... one can learn you base your conclusions on delusions not science.

An Aluminum aircraft cut the outer shell like butter, and cut core columns. There goes your super strength of steel beat by Aluminum. No wonder the planes I fly were strong, they can cut steel.

Your web page is joke to engineers.