'What about building 7'?

[Oystein]

It shows that the column detail that NIST based their analysis on was inaccurate. NIST were fully aware of another drawing called out as 9114 in which the column detail of the girder to C79 connection clearly had stiffeners attached. Instead they chose to model that connection identical to that of C81 with the exception of the angle that the girder framed in at.

NIST claimed publicly to have a level of detail in BOTH models that was incredibly accurate, and to have modelled each connection individually.....


However, the reality is that the model for the critical connection at C79 was simply a duplicate of the C81 connection. The two were not the same.
Even worse, the C79 connection in LSDYNA was not even the correct TYPE of connection.
NIST did not model the connection in the manner they later claimed to have, in either of the models.
They made some corrections and admitted using some incorrect figures in their report, but they did not address the consequences of their errors because to have done so would have invalidated their initiating event theory.
ETA interesting to find that the seat width at the C81 connection was 11", which was what NIST claimed the seat width to be at C79.
As for the 5.5 Vs 6.25" "typo" that they claimed led to this, that brings us back to axial Vs lateral travel, and pgimeno has already stated that the ANSYS element did not in fact indicate the travel failure of the C79 girder.

I meant my question quite literally: WHAT does Drawing #1985 show?

I am guessing from what you write that it's some detail at C81? Floor number? Which seats? And ... how do you know? Sorry, I struggle to make sense of the drawing, but it seems very important.

 

[Spanx]

I meant my question quite literally: WHAT does Drawing #1985 show?

I am guessing from what you write that it's some detail at C81? Floor number? Which seats? And ... how do you know? Sorry, I struggle to make sense of the drawing, but it seems very important.

I think that Gerry is producing this drawing in the hope that someone will look at the connections and say "yes Gerry you are right, it would be impossible for these connections to fail". I would imagine on certain censored sites there would be an awful lot of back patting going on.

The below quote is from the NIST

Several existing, emerging, or even anticipated capabilities could have helped prevent the collapse of WTC 7. The degree to which these capabilities improve performance remains to be evaluated. Possible options for developing cost-effective fixes include:
More robust connections and framing systems to better resist effects of thermal expansion on the structural system.
Structural systems expressly designed to prevent progressive collapse. Current model building codes do not require that buildings be designed to resist progressive collapse.
Better thermal insulation (i.e., reduced conductivity and/or increased thickness) to limit heating of structural steel and minimize both thermal expansion and weakening effects. Insulation has been used to protect steel strength, but it could be used to maintain a lower temperature in the steel framing to limit thermal expansion.
Improved compartmentation in tenant areas to limit the spread of fires.
Thermally resistant window assemblies to limit breakage, reduce air supply, and retard fire growth.
NIST is recommending that building standards and codes be strengthened beyond their current intent to achieve life safety to prevent structural collapse even during infrequent building fires like those in WTC 7 when sprinklers do not function, do not exist, or are overwhelmed by fire.

The suggestions in the above quote appear good to me and make sense that connections fail and thermal expansion exists.

The worrying thing is, Gerry and his team of experts have concerns over safety issues yet they appear to claim that the connections did not fail (with no explanation)

It's fairly obvious to most what gerrys little game is and explains why no one takes him and his "team of experts" seriously

 

[JSanderO]

The below quote is from the NIST
....
More robust connections and framing systems to better resist effects of thermal expansion on the structural system.

Structural systems expressly designed to prevent progressive collapse. Current model building codes do not require that buildings be designed to resist progressive collapse.

This is the key part of the quote. Structural designs appear to ignore that these complex systems are subject to (run away) progressive collapse and this happened in all three towers.

Columns can only buckle or be crushed via excessive load, or decreased capacity such as from removing lateral braces. Thermal expansion of girders or beams will distort a frame and can lead to misalignment of columns and effective loss of axial column capacity... inadequate bearing area.

The column to column connections in the towers were not as the level of the girders and beams but above the floor for ease of fabrication I assume. These splices apparently are not designed to resist lateral movement.

Apparently with lots of heat, inadequate thermal protection and no sprinklering a steel frame is subject to distortion which can destroy its integrity... and result in a runaway progressive collapse.

 

[Miragememories]

"Even if NIST made mistakes in their assumptions, proving them wrong does not in any way prove that a building can not collapse due to fire."

"It in no way proves that it can!"

Indeed, but there's abundant proof of fire, and zero proof of explosives. The null hypothesis is therefore that fire brought it down, and no one has ever made even the start of a case showing otherwise.

When the abundance of fire is inadequate to the task, regardless of your presumed "null hypothesis", like it or not, it becomes necessary to consider other possibilities.

Given the long, long history of steel-structured high-rise buildings tolerating severe fires, and given the lack of comparable collapse precedence prior to 9/11, there is no valid basis for your simple "fire brought it down".

This view of WTC7's south side, viewing from the SE corner indicates a primarily inward collapse.

The main fall back argument for official story supporters is the; "sure an engineered implosion fits what was observed but I watched it on TV and I never heard any explosions."

While the recorded video was generally good, most of the audio recordings from around the World Trade Center on 9/11, were poor, too directional, too local, or too distorted.

While the viewers heard nothing, reporters at the scene, were observed to dramatically turn and react to loud explosive sounds that were never recorded by the microphones they had been speaking into moments earlier.

Many eyewitnesses reported hearing explosions where microphones did not.

The NIST realized that an engineered implosion explained what happened to 7WTC, but they dismissed this hypothesis because they assumed there would be high, easily recorded sound levels.

Of course the NIST looked at the recordings of other building demolitions. Those recorded events that were planned and publicized in advance and not staged in secrecy. Buildings openly prepped, with windows pre-broken and floors cleared of furnishings, allowing for excellent sound echo and projection (ever notice how quiet it is inside an office tower behind those heavy sealed windows?)

In defiance of the NIST's thinking, we have the glaring fact that for the most part, the biggest noises of the day, were not even recorded well, for it is not easy to obtain clean, broad, audio recordings outside of a sound stage unless you have engineered for it.

We know with certainty that cameras recorded the planes impacting both the WTC Twin Towers, the subsequent fireball explosions, the falling debris, the collapses of the Twin Towers, and finally the collapse of 7WTC at 5:20 pm on 9/11.

With all of those recordings, what was most memorable, was the video, and what was the least memorable, or non-existent, was the sound.

And we are not talking traffic noise, we are talking about the gigantic sound signatures of two 110 storey and one 47 storey steel-structured office towers collapsing at high speed.

Watch a TV show or a movie that has a less than pristine images and poor quality audio, and I can tell you as a veteran editor of broadcast TV that the viewer is going to be more bothered by the absent sound quality.

Once the initiating lower floor, core implosion events are triggered, further detonations are smothered by the cacophony of sound from a reacting building.

So the NIST is back to fatal office cubicle fires roaming for 5 floors and around 5 hours in 7WTC.

Office cubicle fires that are supposedly so hot, and so focussed, they caused 8 complete storeys of 7WTC drop like a rock.

 

[Crazy Chainsaw]

I thought the stiffiners were temporarily installed
Steel plates removed after the renivations were
Complete and the drawing Was simply the nessisary
Drawing for the permit for the renivations.
The stiffiners make no logical sense in that
Location once the renovations are complete.

 

[LSSBB]

<clipped for brevity>

Recap:you don't have audio of explosions, and your layman's opinion is the fires could not have been hot enough.

 

[pgimeno]

When the abundance of fire is inadequate to the task, regardless of your presumed "null hypothesis", like it or not, it becomes necessary to consider other possibilities.

The reverse is also true: when it is adequate, as was the case, there's no need, like it or not.

Given the long, long history of steel-structured high-rise buildings tolerating severe fires, and given the lack of comparable collapse precedence prior to 9/11, there is no valid basis for your simple "fire brought it down".

Wow. You need to learn some statistics. There were exactly zero steel high-rises with long span beams that had unfought fires for at least 7 hours, before and after 9/11.

While the recorded video was generally good, most of the audio recordings from around the World Trade Center on 9/11, were poor, too directional, too local, or too distorted.

That's a poor excuse and you know that. In virtually every CD video there are loud booms preceding the fall, no matter how distorted, directional or poor, and in WTC7 there's a dozen or more videos with clear audio and none, zero, zilch exhibit signs of an explosion going off.

But most importantly, your attempts at justifying the absence of proof do not constitute a proof of the presence.

There is still zero proof of explosives.

Many A few eyewitnesses reported hearing explosions where microphones did not.

FTFY. None said these explosions were loud like in a demolition. They may well have been the building cracking.

There are no reports of explosives, detonations, detonation cords, etc. found in the debris post-collapse.

 

[WilliamSeger]

I thought the stiffiners were temporarily installed
Steel plates removed after the renivations were
Complete and the drawing Was simply the nessisary
Drawing for the permit for the renivations.
The stiffiners make no logical sense in that
Location once the renovations are complete.

I believe the stiffener plates are shown in the original placing drawings (at least, that's how the drawings have been represented), but even if they were put there during the renovation, I can't think of any reason to go to the trouble (and unnecessary risk) of removing them.

However, their presence indicates that the designers were concerned about inadequate stiffness in the girder's fully seated, symmetrically loaded position. AE911truth offers nothing but unsubstantiated speculation that the plates were also strong enough to prevent failure if the full load was shifted to only one side of the flange, even if the displacement was less than half-way, and then they would have us "conclude" that a more rational explanation is controlled demolition by magical silent explosives.

 

[Crazy Chainsaw]

I believe the stiffener plates are shown in the original placing drawings (at least, that's how the drawings have been represented), but even if they were put there during the renovation, I can't think of any reason to go to the trouble (and unnecessary risk) of removing them.

However, their presence indicates that the designers were concerned about inadequate stiffness in the girder's fully seated, symmetrically loaded position. AE911truth offers nothing but unsubstantiated speculation that the plates were also strong enough to prevent failure if the full load was shifted to only one side of the flange, even if the displacement was less than half-way, and then they would have us "conclude" that a more rational explanation is controlled demolition by magical silent explosives.

I know that stiffiner plates along with bracing were added during the renovations
A temp structure is removed if it causes
Interferense. With the installation of something else.

 

[Gamolon]

The main fall back argument for official story supporters is the; "sure an engineered implosion fits what was observed but I watched it on TV and I never heard any explosions."

And the main fallback claim used by truthers is that ENTIRE WTC7 structure fell at freefall, in 6 to 7 seconds, followed by a video showing that collapse starting when the roofline begins to descend and skipping anything prior (like the east penthouse collapse).

 

[JSanderO]

The perimeter folded in because the beams attached provide an inward force.... the perimeter was pulled in... certainly not pushed outward... What would push the perimeter outward?

 

[thedopefishlives]

And the main fallback claim used by truthers is that ENTIRE WTC7 structure fell at freefall, in 6 to 7 seconds, followed by a video showing that collapse starting when the roofline begins to descend and skipping anything prior (like the east penthouse collapse).

MM is being disingenuous (as usual). Nobody here has claimed that an engineered implosion fits what was observed. The only people saying that are the Truthers; the rest of us are all saying that an engineered implosion does not fit what was observed. We're not falling back on the "didn't hear no 'splosions" argument, because we're not accepting the premise to begin with. Also, the lack of detonations is itself an observable, so the premise falls flat on its face without having to resort to a fallback argument.

 

[JayUtah]

However, their presence indicates that the designers were concerned about inadequate stiffness in the girder's fully seated, symmetrically loaded position.

Indeed, such a stiffener is almost always meant to prevent buckling of the web, not the deformation of the flange. Since the bearing reaction on a girder is concentrated at its endpoints, those regions of the web are more susceptible to out-of-plane buckling. Further, for many load profiles, the shear within the web builds up at the girder bearings. Thus the same web stiffeners at the bearing ends prevent this internal shear from causing diagonal buckling in the web near the bearings.

AE911truth offers nothing but unsubstantiated speculation that the plates were also strong enough to prevent failure if the full load was shifted to only one side of the flange...

Or even intended to do so. The load-bearing element of a I-section beam or girder is the web, not the flange. The flange exists principally to keep the web in plane along its length. Most deformations of the web substantially reduce the load-bearing capacity of the member.

The AE911T scenario proposes that the bearing stiffener is meant to allow one side of the flange to accept the girder's reaction load after a lateral displacement by preventing the flange from deforming as the footprint of the web exits the bearing seat. They contend that by omitting the stiffener from some models, NIST's analysis allowed the girder-column connection to fail in a condition that, according to them, it would have otherwise survived for longer. They further contend that this omission was intended, in order to provide a straw-man collapse initiation theory.

But this fails for two principal reasons. First, by the time the girder displaces laterally such that the bearing reaction is borne entirely by one side of the girder flange -- and thus invoke the supposed reserve load-bearing intent of the bearing stiffener -- the girder's center of gravity will already have substantially passed the edge of the bearing seat and thus the combination of gravity load and reaction load will tend to rotate the girder. Hence this is not a credible design intent for the stiffener, and thus AE911T's belief in unaccounted reserve strength in the model is unfounded.

Second (and I'm working from memory here), the bearing stiffener does not attach to both upper and lower flanges. Lack of attachments to the flanges is a hallmark of web-only stiffeners. It is true that attachment of the web stiffener to the lower flange allows the portion of the bearing reactions borne by the flange across its total width to be transmitted to the web by the stiffeners. But it is not true that such an arrangement works with an eccentric load such as would occur at only one side of the flange. It works only when both stiffeners have an equal (but practically opposing) axial load.

In the AE911T scenario, an eccentric load on one side only of a flange applies a load through the stiffener to the web in an out-of-plane fashion, borne only by the yield strength in the thickness of the web, increasing (not decreasing) the tendency to buckle the web -- especially when the stiffener does not rise the full height of the web. Instead in the expected case, with a roughly equal portion of the total bearing load on both flange sides, the loads thus transferred from flange to the bearing stiffeners act out-of-plane but in practical symmetrical opposition through the effective section of the stiffeners on both sides, and are borne easily by compression through the thickness of the web at the site of the stiffener attachment. The web itself does not (and cannot) bear those transmitted loads asymmetrically.

The accusation that NIST's failure to include the web stiffener in their computer model means the girder-column connection in the model was less robust than a real life walk-off hypothesis is simply not supported by design practice or careful analysis. It is based on its proponents' speculation of design intent that is not supported by design practice or analysis.

As I've said for many months now, the accusation is meant simply to fool laymen into thinking the accusers have some point that the relevant industries and sciences are expected to address. It appeals to the lay public because it can be expressed simply as discrepancies between one visual representation and another, the congruence of which can be judged without expertise. The implications, however, of that incongruence rely upon expert interpretation to determine how relevant they are to the fidelity of a computer model and how important they are in the further understanding of a forensic structural analysis.

AE911T is all to eager to provide a semblance of that expert interpretation, but one that only seems valid upon cursory reading and does not stand up to evaluation by the industry and relevant sciences. I believe the proponents of that interpretation understand the likely fate their theories would have in the hands of competent structural engineers, which is why they stick exclusively to grass-roots efforts and do not present their findings to the industry and relevant sciences through the customary channels and methods.

 

[gerrycan]

I thought the stiffiners were temporarily installed
Steel plates removed after the renivations were
Complete and the drawing Was simply the nessisary
Drawing for the permit for the renivations.
The stiffiners make no logical sense in that
Location once the renovations are complete.

No. These are not elements that are removed. They're part of the design at the connection between the girder and column 79. You can see them and also the c81 detail in this drawing.

 

[carlitos]

Hi gerrycan,

If you can't be bothered to posit a theory that better explains the "official story" of 9/11, might you enlighten us as to what you are doing by posting here? Is there a goal? Have you made progress towards that goal?

Thanks.

 

[pgimeno]

It is based on its proponents' speculation of design intent that is not supported by design practice or analysis.

I think the latter is not accurate. I remember Szamboti mentioning in another thread an analysis that he made. I don't think that analysis really considered roll-off, though, as he defended that the connections would hold the girder and prevent roll-off. In that thread, Newton's Bit mentioned that the connections would not survive roll-off. I can try to find it if interested.

ETA: http://www.internationalskeptics.com/forums/showthread.php?p=9947605#post9947605 (TS mentions the analysis and NB mentions roll-off)
http://www.internationalskeptics.com/forums/showthread.php?p=9949686#post9949686 (NB gives reasons why the connections won't survive)

But let me fix it for you:

It is based on its proponents' speculation of design intent that is not supported by design practice or sound analysis.

 

[JayUtah]

he defended that the connections would hold the girder and prevent roll-off.

Specifically I see he mentioned fin fittings he (wrongly) believed would prevent rotation in this case. And nothing in his analysis prevents (or even addresses) web buckling from the eccentric load transferred from the flange.

But let me fix it for you:

That's an acceptable edit. I didn't even get to the issue of buckling in the stiffener itself under eccentric load. But that's also a thing.

The TL;DR version is that the notion of the connection at column 79 being essentially impregnable is based on a lot of straw-man reasoning. I think the Truthers know this, and think that's why they don't try to gain credibility with the industry and science via the customary methods.

 

[Crazy Chainsaw]

Specifically I see he mentioned fin fittings he (wrongly) believed would prevent rotation in this case. And nothing in his analysis prevents (or even addresses) web buckling from the eccentric load transferred from the flange.



That's an acceptable edit. I didn't even get to the issue of buckling in the stiffener itself under eccentric load. But that's also a thing.

The TL;DR version is that the notion of the connection at column 79 being essentially impregnable is based on a lot of straw-man reasoning. I think the Truthers know this, and think that's why they don't try to gain credibility with the industry and science via the customary methods.

It looks like the stiffeners that us inertia to decrease buckling would increase the chance of thermal expansion walk off not prevent it, by reducing the beams ability to buckle under gravitational loading, and by providing higher surface area to absorb heat.
That would also explain MM's suggestion on temperature to distort the beams a stiffend beam in theory should be able to use inertia of the stiffeners to absorb more thermal energy!
However I am just a layman working to understand the discussion!

 

[pgimeno]

Specifically I see he mentioned fin fittings he (wrongly) believed would prevent rotation in this case. And nothing in his analysis prevents (or even addresses) web buckling from the eccentric load transferred from the flange.

Web buckling, that's interesting. I guess you mean something like this:

I previously thought that the top flange would yield first, like this.

(not to scale, angle exaggerated for clarity)

 

[JayUtah]

Web buckling, that's interesting. I guess you mean something like this:

[qimg]http://www.formauri.es/personal/pgimeno/xfiles/11-s/web-buckle.png[/qimg]

I do.