• Quick note - the problem with Youtube videos not embedding on the forum appears to have been fixed, thanks to ZiprHead. If you do still see problems let me know.

WTC7 and the girder walk-off between column 79 and 44

Status
Not open for further replies.
Jackanory said:
Concrete doesn’t just crack and expand, it also audibly and visually ‘explodes’ in extreme heat. Not sure at what heat temps but I have attended quite a few IED clear up's to find smouldering wreckage etc and fires on concrete roads. These fires would give off secondary ‘blasts’ that from a distance we initially thought where secondary devices set for the BD teams. Infact, it was the direct heat from the fires being absorbed by the concrete and the concrete ‘exploding’ leaving a very distinctive crater. I should imagine that the concrete floors in all WTC’s reacted in a similar manner too.

Chris7 could try a simple experiment at home. Try burning some wood, office equipment etc on your concrete driveway......see what happens.
Click to expand...

Spalling, which happens naturally but indeed can be dramatic in a fire.

examples
 
GlennB said:
Spalling, which happens naturally but indeed can be dramatic in a fire.

examples
Click to expand...

'Dramatic in fire' indeed. Those fires caused 'craters' that where 6" - 8" deep into solid road bearing class 60 concrete. We initially thought that this was potentially due to fuel or oil penetration into the concrete from spills or leaks etc but it was infact as a result of the heat generated from the burning of the soft furnishings from the vehicle in question, tyres, clothing from the personel inside or the bodies themselves. It didn't just crack, it would eject splinters and chunks of concrete as it 'exploded'.
 
jaydeehess said:
Another point would be to question what the steel column would do to concrete it is pressing against if it cannot move that concrete slab. Would it cause the exterior wall system tyo push out or would it spall and break pieces of the concrete.
Remember the concrete is hot, not through its entire volume as hot as the steel but certainly the surfaces of the concrete are hot and what does concrete do when hot? It is prone to spalling.

I would suppose that NIST did not take into account any lateral support from the slab simply because a thin floor slab cannot offer anything close to the same support that a steel girder can.
Click to expand...

Jackanory said:
Concrete doesn’t just crack and expand, it also audibly and visually ‘explodes’ in extreme heat. Not sure at what heat temps but I have attended quite a few IED clear up's to find smouldering wreckage etc and fires on concrete roads. These fires would give off secondary ‘blasts’ that from a distance we initially thought where secondary devices set for the BD teams. Infact, it was the direct heat from the fires being absorbed by the concrete and the concrete ‘exploding’ leaving a very distinctive crater. I should imagine that the concrete floors in all WTC’s reacted in a similar manner too.

Chris7 could try a simple experiment at home. Try burning some wood, office equipment etc on your concrete driveway......see what happens.
Click to expand...

Seems we had similar thoughts about hot surface concrete under pressure.
 
Jackanory said:
'Dramatic in fire' indeed. Those fires caused 'craters' that where 6" - 8" deep into solid road bearing class 60 concrete. We initially thought that this was potentially due to fuel or oil penetration into the concrete from spills or leaks etc but it was infact as a result of the heat generated from the burning of the soft furnishings from the vehicle in question, tyres, clothing from the personel inside or the bodies themselves. It didn't just crack, it would eject splinters and chunks of concrete as it 'exploded'.
Click to expand...

Roadway concrete would react slightly differently than light weight floor slab. While Iraq is not known as a wet climate, the interior of a decades old structure would have concrete with even less moisture content. Exploding concrete such as what you describe is often attributable to what is basically a steam explosion within the concrete. Obviously in Iraq or Afghanistan the surface is likely quite dry but concrete does absorb water and the deeper you go into a roadway the more moisture content from past precipitation. This of course only requires the wetter levels of that concrete reach a little over 100 degrees C. The vapourizing water cannot escape fast enough and pressure builds until it exceeds the ability of the concrete to hold together and you get the explosion you describe.
Although I do not know the particulars I would also suspect that dense roadway concrete would also conduct heat much better than light weight, less dense, concrete.
Structural concrete columns and floors can be made to react better in fires with the addition of fiberglass fibers which will allow steam to escape acutally cooling the hotter surface layers while also reducing spalling due to vapour pressures.

At least from what I have read on the subject.

So I would expect lesser 'explosions' and less dramatic spalling of surface layers.
 
Last edited:
jaydeehess said:
Seems we had similar thoughts about hot surface concrete under pressure.
Click to expand...

I can only make assumptions of course but from my own experience, albeit in a totally different evironment, I witnessed what fire does to concrete in the open. Given that fires raged inside those building, not only from below each floor but acting directly onto each concrete floor, I can imagine this 'spalling' happening everywhere. Potentially 'blasting' 6" - 8" holes through the concrete as I have seen before. Added to the expansion and retraction effects going on and the distribution of heat through columns, beams, girders, floorpans etc it is hardly surprising that the building collapsed.

Did NIST mention 'spalling'. If not, then perhaps we need a new investigation:rolleyes:

EDIT - Above written before reading your previous post explaining the different properties of concrete. Point taken.
 
Last edited:
What happened to gerrycan?

"geeeeeeeeeeerrycan", "oh geeeeeeeeerrryyyycannnnnn".

Oh well, at least SHC is back:rolleyes:
 
Jackanory said:
What happened to gerrycan?

"geeeeeeeeeeerrycan", "oh geeeeeeeeerrryyyycannnnnn".

Oh well, at least SHC is back:rolleyes:
Click to expand...

Awww, it's nice that you missed me. Been busy with other things. The spalling thing is interesting, and I have a few papers on that here, but generally, i feel that the misrepresentation of the drawings on the part of NIST is just being ignored by most of you here. I do welcome an open and frank discussion of that, and will keep an eye on the thread to see if that happens.
 
gerrycan said:
Awww, it's nice that you missed me. Been busy with other things. The spalling thing is interesting, and I have a few papers on that here, but generally, i feel that the misrepresentation of the drawings on the part of NIST is just being ignored by most of you here. I do welcome an open and frank discussion of that, and will keep an eye on the thread to see if that happens.
Click to expand...

Hopefully you have been busy getting some real time experience with explosives or thermi*e. Perhaps painting you gate.

Think I'll pass. Can see this turning into a 'derivative of therm*te' clownshoot.
 
gerrycan said:
unrestrained thermal expansion (no resistance) would be around 5.7" for the longest of the floor beams to the east of the girder at NISTs temperature estimate. Not enough to cause the girder to walk off.
Click to expand...

OK Ive had about enough of this nonsense, In your opinion, How much expansion would be needed MID SPAN of this beam between columns 44 and 79 to cause its WEB CENTER LINE to be PAST the seat at either end? This is without moving the ends on the seats or knife connections whatsoever. What would prevent such an eccentrically loaded beam from rotating?
 
A W Smith said:
OK Ive had about enough of this nonsense, In your opinion, How much expansion would be needed MID SPAN of this beam between columns 44 and 79 to cause its WEB CENTER LINE to be PAST the seat at either end? This is without moving the ends on the seats or knife connections whatsoever. What would prevent such an eccentrically loaded beam from rotating?
Click to expand...

nonsense? Are you talking about plate pf and do you mean the girder between 79 and 44? the beams are to the east of it. and its the beams to the east whos expansion nist blame, not expansion of the girder....please clarify.
 
gerrycan said:
nonsense? Are you talking about plate pf and do you mean the girder between 79 and 44? the beams are to the east of it. and its the beams to the east whos expansion nist blame, not expansion of the girder....please clarify.
Click to expand...
yes correction the girder between 79 and 44, if the beams to the east expand and the ends of girder between 79 and 44 are restrained, What prevents that girder from bowing to the west? And resisting rotation?
 
Last edited:
pgimeno said:
gerrycan said:
One is push only, the other i believe is push then pull.
Click to expand...

Before or after the rocking?
Click to expand...

Bump. How can a "push then pull" be "almost the opposite" than push only?

What's wrong with the concept of a displaced girder with just 0.5" support twisting out of the seat?

Regardless of the correctness of your assessment on that girder, do you have a replacement theory? You know, Newton's theory is wrong in some details, but is still useful and used today. Critics didn't just say "Look how things behave at speeds near light speed. Newton's Laws are false and can't be taken seriously! They must be abolished!". Maxwell, Lorenz, Einstein, etc. went ahead and elaborated complete models and theories that could describe and replace Newton's. Do you have one, or just pointing fingers and complaining, like most people in the 911TM have been doing for more than 10 years now?
 
Status
Not open for further replies.

Back
Top Bottom