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ORIGINAL: thornhappy

That's she, nimrod.  The problem with all your points is that they're stone incorrect, as Animus has pointed out.

BTW, what did you think of the aeroweb analyses?

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ORIGINAL: Real0ne

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ORIGINAL: thornhappy

I guess he's talking to me...but I've given him this info before.  He doesn't believe it.  Go to the FEMA engineering analysis; in chapter 2 there are pictures of debris.
http://www.fema.gov/pdf/library/fema403_ch2.pdf
(btw, here's the analysis of WTC7 http://www.fema.gov/pdf/library/fema403_ch5.pdf)

Just because I am in a good mood and had a few beers and kicked back and relaxed and all that shit I will take the time to explain a few things to you.

The title I assigned to this little lesson was physics for retards 101.

retards cannot think for themselves until they have several red faces and even then I am lucky to save 1 in 100.

In laymans terms:
When an expanse of steel in this case is heated the metal expands up the point it losses its structural strength due to heating and begins to sag.

The sagging takes place because it cannot support the load placed upon it.

The column held the load prior to heating then majically became overloaded. 

Where did the additional load come from and what gave it increased strength to pull in the columns that it could not before the fire?  Heavy fire maybe?

The floor sagged because it lost its strength but majically has more strength than it originally had in that it pulled the columns inward!

Use your heads people, if the floor lost strength its impossible to pull the fucking columns inward.

when the floor losses strength to the point it is sagging the metal is stretching like taffy due to loss of strength.  That means it now has less strength and is only capable of putting less force then original design on the columns and less ability to pull the columns inward. 

just like when the floor slowly sags to the point it touches the floor below it is now out of the "hot" zone of the (in this case mostly invisible), flames and cools.

Therefore global failure cannot occur.

you people really need to wise up and start using your heads.  If you have brains in them.

ahz beleeves I showly does beleeves!







oh that picture is out of your honest joe government link btw.....

Oh now if you wanna know what would cause the columns to buckle inward?  That is really a simple scenario as demonstrated by the demolition of wtc1.

Blow the core first.  We seen this when the antenna fell 20 feet before the rest of the building started to move.

So we know they took out the core first.

It would suck anything attached to it inward exoskeleton included.

Very well thought out demolition if I do say myself.

Sorry if I am laughing.

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ORIGINAL: SL4V3M4YB3
Stop it with this game of silly beggars, you is wrong!

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ORIGINAL: Real0ne
joint rotation wont twist the column sideways.

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The only way you can get a global collapse of that system is if the slabs are prestressed and even then it would be a very specific failure mode with precise conditions.
little 4" conrete nonstressed slabs just break up and crack with any kind of significant flexure of its base.

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secondly you would need enough fire to at a minimum envelop the whole floor, not just one or 2 or 10 and it would need ot be uniform and it sorta was in 1975 on the 11th floor and oops didnt come crashing down now did it.

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Long story short I do not believe you know anything about structural anglneering.

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aww what a bummer the gif of the sagger proving my point is to large for this lame board. Oh well enjoy this one instead:

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ORIGINAL: SeekingAZ

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ORIGINAL: SeekingAZ

quote:

ORIGINAL: Real0ne






oh that picture is out of your honest joe government link btw.....

Oh now if you wanna know what would cause the columns to buckle inward?  That is really a simple scenario as demonstrated by the demolition of wtc1.

Blow the core first.  We seen this when the antenna fell 20 feet before the rest of the building started to move.

So we know they took out the core first.

It would suck anything attached to it inward exoskeleton included.

Very well thought out demolition if I do say myself.

Sorry if I am laughing.

nothing you said was on point.  you dont even know the difference between sheathing and loading.

While what you said is great copy and paste now all you need to do is go get some schooling under your belt to understand what it all means and how it does not apply to my point eh...

"They blew the core first ?" The vertical structural components of the trade center were the exterior steel risers. If i'm not mistaken a new idea at the time of the WTC's construction in order to maximize usable interior space (and therefore potential rental income).

Once the steel floor joists buckled that exterior vertical steel was no longer supported/braced at those levels and could not support the weight of the floors above it without buckling in compression and therefore breaking the connection with yet more steel floor joists which weakened the vertical steel further, etc.

Traditional construction with the majority of the structural components in the core probably would of failed on impact (instead of giving people an hour or so to get out) because the majority of those components would of been severed when the multi-ton 500 knot aircraft went through.

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ORIGINAL: SL4V3M4YB3

quote:

ORIGINAL: Real0ne
joint rotation wont twist the column sideways.

Depends on the relative stiffness of the beam and column, along with what you mean by sideways.

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The only way you can get a global collapse of that system is if the slabs are prestressed and even then it would be a very specific failure mode with precise conditions.
little 4" conrete nonstressed slabs just break up and crack with any kind of significant flexure of its base.

You need to do some research on composite structures, the slab is acting as a compression flange so adds to the overall bending resistance of the beam. When that compression flange fails in crushing there is an immediate redistribution of that moment into the beam below. If the beam is incapable of taking that new moment then it will fail. The truss alone does not withstand the bending stress (steel is expensive and concrete is cheaper) this is the whole point of composite design; to reduce beam depth and amount of steel. So in your WTC example the steel is losing its bending strength and passing some of the bending stress into the slab above.

Think of the failure type along the lines of an R.C. beam. YOU NEVER OVER REINFORCE CONCRETE because you want the concrete to fail before the steel rebar within it does. If the steel rebar reaches yield point first then the collapse is sudden because the redistributed moment jumps directly into the concrete and it can’t take it. The moment has to go somewhere once the resistance of one component changes.

I don’t know how to explain this in more simple terms to a simpleton such as yourself. You aren’t using your imagination and you are still thinking of slab and truss acting as separate elements. The main problem I know of regarding pre-stressing is sometimes you can relieve the load from below causing it to snap upwards but this is a different issue altogether. Also in the modern sense this risk is now mitigated by ensuring better end fixity.

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secondly you would need enough fire to at a minimum envelop the whole floor, not just one or 2 or 10 and it would need ot be uniform and it sorta was in 1975 on the 11th floor and oops didnt come crashing down now did it.

The failure mechanism for the WTC is well documented. The short version is: the impact of the plane stripped off fire protection to columns and exposed it directly to fire. You will not find many steel buildings that remain standing for long if directly exposed to fire. The buildings themselves also didn't have much of a key element design philosophy to them either. Also as I pointed out previously; steel conducts heat quite well so only small portions of it need to be exposed directly for the heat to then be conducted throughout the frame locally. Also perhaps you have water from sprinkler systems spreading around a liquid fuel fire (no foam in such systems as they are not expected to deal with liquid fuel fires.)

Columns are quite critical, the example I showed had fire protection to the columns because they were only looking at composite beam deflection. Those test buildings may have collapsed further if there wasn’t any fire protection to the columns.

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Long story short I do not believe you know anything about structural anglneering.

Well I have difficulty believing you know how to wipe your own arse, so we are all entitled to our opinion of one another aren't we?

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aww what a bummer the gif of the sagger proving my point is to large for this lame board. Oh well enjoy this one instead:

I forget what your exact point was, I think it goes somewhere along the lines of 'Look everyone I'm a Prat.'

You've talked of many things. If you ultimately believe a plane crashing into a building then causing a fire throughout a whole floor or two can't release all the potential energy of the structure above and turn it into kinetic energy, then you is a bit mentally challenged. Your point as to which direction columns should or shouldn't buckle is a complete diversion. Like I said earlier columns need lateral support at each level to work efficiently. So even if (and it’s a big unrealistic if) floor deflection doesn't cause joint rotation then the column at least is going to lose its lateral support at that level meaning the effective length is too great to support the load above.

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ORIGINAL: Real0ne

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ORIGINAL: thornhappy

That's she, nimrod.  The problem with all your points is that they're stone incorrect, as Animus has pointed out.

BTW, what did you think of the aeroweb analyses?

nice generalization.  last time you tried to correct me your got your nose rubbed in it.  So point out where you think I am incorrect.  I have the newspaper rolled up and ready to go!

Oh and I see you did not bother to post my response to what he said either did you!

What a loser!  I am not gonna repeat the shit because you try to skew the tables.

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ORIGINAL: SL4V3M4YB3

I'm not really going to respond to your latest batch of lunacy other than to say you read what I said wrong. If you can't even understand what is said and attribute other meanings to what a person said rather than the true meaning then discussion is going to be rather impossible.

I didn't restate any of your points or accept them as true

I didn't contradict anything I said previously

I didn't say any magic was involved in composite action

The concrete is not just laid on top of the steel beam, Mr Moron, it is tied in place with shear studs or welded loops of rebar allowing stresses to be developed in the slab from bending action transferred from the top flange of the beam. The 'two tooth picks' example is stupid because both toothpicks have an equal resistance to both tension and compression; (the material properties are the same). Concrete is weak in tension but strong in compression, steel is both strong in compression and tension. A better analogy is a timber joist with metal strip nailed to the underside.

No further discussion will be entered into on this topic with myself, I realised the other day that I wouldn't engage a crazy person in the street so I'm an idiot to try to do so on the internet.

Besides which you aren’t really listening, if you think to any extent I have reinforced or endorsed your crazy position.

Adios.