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

[BasqueArch]

Some form of demolition device is what I would say.

That sounds kinda vague, lacking the precision you claim to admire.
There were no explosive blasts therefore explosives are impossible.

 

[Tony Szamboti]

That sounds kinda vague, lacking the precision you claim to admire.
There were no explosive blasts therefore explosives are impossible.

You shouldn't knock the lack of precision here, as all one can honestly do is eliminate the impossible.

What we know is the NIST explanation for the collapse initiation due to fire was in fact impossible, and all other possibilities that have been looked at have been found to be even less viable than what NIST proferred. That leaves an artificial removal of the column as the cause for failure. Beyond that would be conjecture and more precision is impossible at this point.

 

[BasqueArch]

All I can say is that column 79 definitely came down and it couldn't have been due to fire, so some form of artificial demolition device was used to remove it. It doesn't have to be explosives.

Dude
I quoted you and posted my reply and then after you read mine you changed it.

 

[Tony Szamboti]

Dude
I quoted you and posted my reply and then after you read mine you changed it.

No, I didn't. I was editing without knowing you were replying so fast. I hadn't read your next post before editing that initial reply to you.

 

[BasqueArch]

You shouldn't knock the lack of precision here, as all one can honestly do is eliminate the impossible.

What we know is the NIST explanation for the collapse initiation due to fire was in fact impossible, and all other possibilities that have been looked at have been found to be even less viable than what NIST proferred. That leaves an artificial removal of the column as the cause for failure. Beyond that would be conjecture and more precision is impossible at this point.

You first typed that it didn't have to be explosives, it could have been through some other means. You changed this again.

You're backing off explosives, so that's out.

The girder fell off the seat because the seat bent or sheared.
The girder sagged more than the calculated 2 inches or so because first it buckled through axial expansion trapped by the two columns and by the eccentric push of the top placed expanding beams. Once the girder buckles it loses its geometry and strength and the deflection is much greater than ~2". This places the load at the heated unstiffened col 79 seat tip, this fails and the girder slides off.


]Detail A below shows the initial conditions as drawn.

Detail B below shows the girder displacement as calculated by TS without the column 76 girder push. The girder load is at the tip of the cantilevered seat.

Detail B1 below shows the girder displacement with the 1” column 76 girder push. The girder load is at the tip of the 4 7/16” cantilevered seat.
“The temperature of the girder between Columns 76 and 79 on Floor 13 was sufficient to displace Column 76 to the west and Column 79 to the east.” (NCSTAR 1-9 p527).

Detail C shows the sagging girder with a 20” deflection, similar to the beams deflection modeled by NIST. Any girder deflection would place the girder load at the tip of the cantilevered seat.

Detail D shows the condition at 13th floor Column 79 seat. The 83.7k load was calculated at 100 psf for 837 sf of area at the tip of the 4 7/16” cantilevered seat. It looks like torque would fail the seat in bending or shear and the girder would slide off, but I can’t do the math.

NIST didn’t consider the vertical failure of the seat and its model included a seat stiffener at Col 79 not shown in the plans.
“Since vertical failure of the seat was not considered (Section 11.2.5), the connections at Columns 79 and 81 were both modeled as stiffened seats.” (NCSTAR 1-9 p.558) See “Figure 12-25 Seat connection in global model Column 79. (p. 559)

The conclusions that the columns, beams and girders failed by fire were the result of the Fire Dynamics Simulator (FDS), FEA - ANSYS and LS-DYNA models over time.
NCSTAR 1-9 p 536 “ The ANSYS model included nonlinear effects, such as: nonlinear temperature-dependent material properties including thermal expansion, plasticity and creep; nonlinear geometry; and user defined elements that captured the details of temperature dependent connection failures.”

Other forces unaccounted for in the above details leading to failure of this girder or buckling of Column 79:

• Twisting and failure of the girder at the Critical Twist Angle:

NCSTA 1-9 p487 " When lateral support of the top (compression) flange was lost, floor beams and girders could laterally displace and buckle in a lateral-torsional mode. ...If a beam or girder twisted half of its flange width laterally, it would not be able to support its gravity loads. ….Figure 11-19. Critical Twist Angle in Beams/Girders." The beams framing onto the girders were eccentrically located at the top section of the girder.

• Lagging differential expansion of the concrete due to the fires on the 12th and 13th floors bearing and laterally pushing on the girder.
• At Column 79 Floors 6-13 failure of the bolts or welds for the two girder fin supports. Loss of east-west horizontal support of the columns over 8 floors shown. (NCSTAR 1-9A Figure 4-17 p. 81)

The opinion that fires had nothing to do with the collapse of WTC7 is political and false.[/quote]

 

[Tony Szamboti]

You first typed that it didn't have to be explosives, it could have been through some other means. You changed this again.

You're backing off explosives, so that's out.

The girder fell off the seat because the seat bent or sheared.
The girder sagged more than the calculated 2 inches or so because first it buckled through axial expansion trapped by the two columns and by the eccentric push of the top placed expanding beams. Once the girder buckles it loses its geometry and strength and the deflection is much greater than ~2". This places the load at the heated unstiffened col 79 seat tip, this fails and the girder slides off.


]Detail A below shows the initial conditions as drawn.
[qimg]http://desmond.imageshack.us/Himg96/scaled.php?server=96&filename=wtc7a.jpg&res=landing[/qimg]
Detail B below shows the girder displacement as calculated by TS without the column 76 girder push. The girder load is at the tip of the cantilevered seat.
[qimg]http://desmond.imageshack.us/Himg818/scaled.php?server=818&filename=wtc7b.jpg&res=landing[/qimg]

Detail B1 below shows the girder displacement with the 1” column 76 girder push. The girder load is at the tip of the 4 7/16” cantilevered seat.
“The temperature of the girder between Columns 76 and 79 on Floor 13 was sufficient to displace Column 76 to the west and Column 79 to the east.” (NCSTAR 1-9 p527).
[qimg]http://desmond.imageshack.us/Himg217/scaled.php?server=217&filename=wtc7b1.jpg&res=landing[/qimg]

Detail C shows the sagging girder with a 20” deflection, similar to the beams deflection modeled by NIST. Any girder deflection would place the girder load at the tip of the cantilevered seat.

[qimg]http://imageshack.us/photo/my-images/845/wtc7c.jpg/[/qimg][qimg]http://img845.imageshack.us/img845/9341/wtc7c.jpg[/qimg]

Detail D shows the condition at 13th floor Column 79 seat. The 83.7k load was calculated at 100 psf for 837 sf of area at the tip of the 4 7/16” cantilevered seat. It looks like torque would fail the seat in bending or shear and the girder would slide off, but I can’t do the math.

NIST didn’t consider the vertical failure of the seat and its model included a seat stiffener at Col 79 not shown in the plans.
“Since vertical failure of the seat was not considered (Section 11.2.5), the connections at Columns 79 and 81 were both modeled as stiffened seats.” (NCSTAR 1-9 p.558) See “Figure 12-25 Seat connection in global model Column 79. (p. 559)
[qimg]http://imageshack.us/photo/my-images/855/wtc7d.jpg/[/qimg]
[qimg]http://desmond.imageshack.us/Himg855/scaled.php?server=855&filename=wtc7d.jpg&res=landing[/qimg]

The conclusions that the columns, beams and girders failed by fire were the result of the Fire Dynamics Simulator (FDS), FEA - ANSYS and LS-DYNA models over time.
NCSTAR 1-9 p 536 “ The ANSYS model included nonlinear effects, such as: nonlinear temperature-dependent material properties including thermal expansion, plasticity and creep; nonlinear geometry; and user defined elements that captured the details of temperature dependent connection failures.”

Other forces unaccounted for in the above details leading to failure of this girder or buckling of Column 79:

• Twisting and failure of the girder at the Critical Twist Angle:

NCSTA 1-9 p487 " When lateral support of the top (compression) flange was lost, floor beams and girders could laterally displace and buckle in a lateral-torsional mode. ...If a beam or girder twisted half of its flange width laterally, it would not be able to support its gravity loads. ….Figure 11-19. Critical Twist Angle in Beams/Girders." The beams framing onto the girders were eccentrically located at the top section of the girder.

• Lagging differential expansion of the concrete due to the fires on the 12th and 13th floors bearing and laterally pushing on the girder.
• At Column 79 Floors 6-13 failure of the bolts or welds for the two girder fin supports. Loss of east-west horizontal support of the columns over 8 floors shown. (NCSTAR 1-9A Figure 4-17 p. 81)

The opinion that fires had nothing to do with the collapse of WTC7 is political and false.

Any buckling due to expansion would have been very mild and would not have caused much shortening. Shortening of the girder due to sag wasn't that significant either. We have already been through this on this thread, and the axial shortening of the girder due to both mild buckling and sag is not nearly sufficient to cause it to fall off the seat either.

NIST would have jumped right on this if it were even remotely plausible.

 

[BasqueArch]

We have already been through this on this thread, and the axial shortening of the girder is not nearly sufficient to cause it to fall off the seat either.[/quote]

Yes we have been through this and you have been consistently wrong. The deflection of a buckled girder is much greater than the calculated deflection of an unbuckled simple beam.
The seat failed and the girder slid off.

 

[Tony Szamboti]

Yes we have been through this and you have been consistently wrong. The deflection of a buckled girder is much greater than the calculated deflection of an unbuckled simple beam.
The seat failed and the girder slid off.

I have asked you for calculations to back up what you say and you reply that you can't do the calculations. How do you then insist on what you are saying?

My calculations show that any buckling and axial shortening do not produce enough axial movement to cause the girder to move past the 2" wide x 14" deep plate under the bearing seat at column 79.

 

[Animal]

We have already been through this on this thread, and the axial shortening of the girder is not nearly sufficient to cause it to fall off the seat either.

Yes we have been through this and you have been consistently wrong. The deflection of a buckled girder is much greater than the calculated deflection of an unbuckled simple beam.
The seat failed and the girder slid off.[/QUOTE]

The floor beams also buckled in the simulation, They could have been displaced off their bearing seat at the perimeter, with the result of all the floor load transferring to te girder which would have caused it to twist as well, creating an even greater point load on the the seat at col 79,

 

[BasqueArch]

Any buckling due to expansion would have been very mild and would not have caused much shortening. Shortening of the girder due to sag wasn't that significant either. We have already been through this on this thread, and the axial shortening of the girder due to both mild buckling and sag is not nearly sufficient to cause it to fall off the seat either.

NIST would have jumped right on this if it were even remotely plausible.

NIST eliminated this possibility by adding a stiffener to the seat.
This eliminated consideration of seat faiklure as a cause. Remember you said all NIST simplification was slanted to prove failure; that's wrong also.

NIST didn’t consider the vertical failure of the seat and its model included a seat stiffener at Col 79 not shown in the plans.
“Since vertical failure of the seat was not considered (Section 11.2.5), the connections at Columns 79 and 81 were both modeled as stiffened seats.” (NCSTAR 1-9 p.558) See “Figure 12-25 Seat connection in global model Column 79. (p. 559)

You're not following me or reading the information I have provided. One possible means of girder failure. I drew pictures of this. The erection bolts had sheared, the girder buckled, it sagged, this placed the weight of its load at the tip of the hot seat, it failed, the girder slid off.

 

[Tony Szamboti]

NIST eliminated this possibility by adding a stiffener to the seat.
This eliminated consideration of seat faiklure as a cause. Remember you said all NIST simplification was slanted to prove failure; that's wrong also.

NIST didn’t consider the vertical failure of the seat and its model included a seat stiffener at Col 79 not shown in the plans.
“Since vertical failure of the seat was not considered (Section 11.2.5), the connections at Columns 79 and 81 were both modeled as stiffened seats.” (NCSTAR 1-9 p.558) See “Figure 12-25 Seat connection in global model Column 79. (p. 559)

You're not following me or reading the information I have provided. One possible means of girder failure. I drew pictures of this. The erection bolts had sheared, the girder buckled, it sagged, this placed the weight of its load at the tip of the hot seat, it failed, the girder slid off.

I understand that NIST used an axial stiffener at the column 79 side similar to what there was at the column 44 side and this is wrong. Please tell NIST you want the model changed. I agree with you there.

All I am saying is my calculations don't show enough axial shortening for the end of the girder to be positioned axially beyond the actual 2" thick x 14" deep stiffener below the bearing seat. So my calculations do not support your contention.

 

[BasqueArch]

................

The floor beams also buckled in the simulation, They could have been displaced off their bearing seat at the perimeter, with the result of all the floor load transferring to te girder which would have caused it to twist as well, creating an even greater point load on the the seat at col 79,

They even showed an illustration of the beams twisting the girder

NCSTA 1-9 p487 " When lateral support of the top (compression) flange was lost, floor beams and girders could laterally displace and buckle in a lateral-torsional mode. ...If a beam or girder twisted half of its flange width laterally, it would not be able to support its gravity loads. ….Figure 11-19. Critical Twist Angle in Beams/Girders." The beams framing onto the girders were eccentrically located at the top section of the girder.

 

[BasqueArch]

I understand that NIST used an axial stiffener at the column 79 side similar to what there was at the column 44 side and this is wrong. Please tell NIST you want the model changed. I agree with you there.

All I am saying is my calculations don't show enough axial shortening for the end of the girder to be positioned axially beyond the actual 2" thick x 14" deep stiffener below the bearing seat. So my calculations do not support your contention.

I derived my drawings from the displacements you provided. And even then the girder doesn't have to shorten. It's displaced and hanging by half a fingernail on the small, short seat. All is needs is sheared bolts and sagging to place the load at the tip of the hot unstiffened seat and slide off.

 

[Tony Szamboti]

They even showed an illustration of the beams twisting the girder

NCSTA 1-9 p487 " When lateral support of the top (compression) flange was lost, floor beams and girders could laterally displace and buckle in a lateral-torsional mode. ...If a beam or girder twisted half of its flange width laterally, it would not be able to support its gravity loads. ….Figure 11-19. Critical Twist Angle in Beams/Girders." The beams framing onto the girders were eccentrically located at the top section of the girder.

You have no idea what the inputs were to their finite element model, as they won't release them. They also did not include the beam stubs framing into beam G3005 from the north exterior wall.

I did a finite element analysis with the five beams and the girder at 600 degrees C with and without those beam stubs and the only beam that buckled was G3005 and that was only without the beam stubs.

What you fail to realize is that when G3005 expands it is trying to rotate the girder about the pivot created in between the flanges of column 44. The next beam in is then in tension since the girder is trying to move laterally more than that beam expands at their connection. If that beam is in tension it can't buckle due to lateral-torsional buckling. These are the types of things which make the NIST story fall apart.

It certainly seems like they left certain things out like the beam stubs and girder stiffeners at the column 79 side to make their story more plausible. Use of the wrong stiffener below the girder bearing seat at column 79 seems to be just a bonehead mistake which should also be corrected.

 

[000063]

Most aren't aware since this topic has not been covered much in the press.

All of my engineering colleagues, that I showed the collapse of WTC 7 to and then explained what the present official story for it was, thought the present official story to be ridiculous.

And you think your verbal explanation is the same as the detailed and comprehensive NIST report endorsed by the ASCE and used to build better buildings?

Do you know what the representative sample is for every engineer in the world? Let's lowball it at a million. How many would be considered a representative sample, at a 5% margin of error, and have you talked to that many people?

 

[Oystein]

Again you show your ignorance. The science behind building stable structures is not specific to one area.

But intuition is usually limited to the scales and materials one is accustomed to. Few MEs have experience with such tall, fragile, mostly empty structures such as highrises.

I am pretty sure your colleagues haven't studied the structural blueprints and done the math. You may have given them a summary of your bunk, not the real "official" story. Have you tried giving the executive summary of the NIST report on WTC7 to any of your colleagues without comment, and see what they think unaided by you?

 

[BasqueArch]

You have no idea what the inputs were to their finite element model, as they won't release them. They also did not include the beam stubs framing into beam G3005 from the north exterior wall.

I did a finite element analysis with the five beams and the girder at 600 degrees C with and without those beam stubs and the only beam that buckled was G3005 and that was only without the beam stubs.

What you fail to realize is that when G3005 expands it is trying to rotate the girder about the pivot created in between the flanges of column 44. The next beam in is then in tension since the girder is trying to move laterally more than that beam expands at their connection. If that beam is in tension it can't buckle due to lateral-torsional buckling. These are the types of things which make the NIST story fall apart.

It certainly seems like they left certain things out like the beam stubs and girder stiffeners at the column 79 side to make their story more plausible. Use of the wrong stiffener below the girder bearing seat at column 79 seems to be just a bonehead mistake which should also be corrected.

That one norther beam with the parallel stubs. Both the stubs and the beam were heated, the beam had to expand. If the beam was restrained it had to buckle. You didn't consider vertical buckling of this beam the stubs and connections were weak in this axis.

Column 79 failed due to insufficient bracing over several floors. It had no E-W bracing over ~8 floors. The failure of girder 79-44 was one probable cause of the column failure.

Fire caused the collapse of WTC7.

 

[Tony Szamboti]

But intuition is usually limited to the scales and materials one is accustomed to. Few MEs have experience with such tall, fragile, mostly empty structures such as highrises.

I am pretty sure your colleagues haven't studied the structural blueprints and done the math. You may have given them a summary of your bunk, not the real "official" story. Have you tried giving the executive summary of the NIST report on WTC7 to any of your colleagues without comment, and see what they think unaided by you?

I gave them both sides of the story and links to several videos. They arrived at the conclusion that the present official story for the collapse of WTC 7 is bunk on their own.

Again you are showing your ignorance by thinking a mechanical engineer doesn't understand what slenderness means in reference to structural members such columns and beams.

 

[000063]

Another pathetic comment, but with an attempt to appeal to firefighters training as though they would all agree that the building would collapse without any details or further explanation.

Straw man. No one has asserted such.

You shouldn't be trying to hide behind anyone, so tell us why you think a bulge at floors 10 to 13 on the southwest corner of the 300 foot long x 144 foot wide WTC 7 was in any way indicative of a full or even partial collapse of the building.

It wasn't. It was indicative of severe structural damage, the equivalent of broken bones making bumps in the skin, your incredulity notwithstanding.

All I can say is that column 79 definitely came down and it couldn't have been due to fire, so some form of artificial demolition device was used to remove it. It doesn't have to be explosives.

Which promptly leads to the question of how they knew exactly how 7 was going to be damaged in order to plant said devices.

Only one Truther has ever answered this when I asked, and his claim was basically appeal to magic.

 

[NoahFence]

There were still a few hundred firefighters who survived and were on the scene after the devastation when the towers collapsed. It wouldn't take that many firefighters to hook up to the siamese fittings and man the pumpers to keep the pressure on the water from the fireboats.

From what I understand, throughout the afternoon many firefighters were wondering why they weren't doing it.

Despite what you people insist on believing, the fact was WTC7 was simply not a high priority. WTC6 had live ammo inside. Higher priority.