Total Building Collapse from a Single Column Failure

[Newtons Bit]

NIST says they put the beams at one temperature and did not use a gradient in the structural analysis.

Additionally, the values I showed for buckling the beams and shearing the bolts are the minimums and they significantly exceed any reaction force the girder could have applied, so the beams would not buckle and their connection bolts to the girder would not break. The comments by some here of that type of thing happening is simply not supportable.

What was the force on the bolts post buckling?

 

[Tony Szamboti]

What was the force on the bolts post buckling?

What are you saying buckled? The beams framing into girder A2001 from the east?

If so, I don't see how the beams buckled with an insufficient reaction force from girder A2001 without shear studs on it, so your question would not be germane.

 

[Animal]

What was the force on the bolts post buckling?

Remember TS previously hand waved this away.
Connection damage was typically gradual, with bolts and/or welds failing sequentially over time."
(pg 490 NIST NCSTAR 1-9)

In trooferland, every action takes place independently........allowing him to hand wave away anything that threatens his religious beliefs.

 

[Muc]

Take care this does not go "Off Topic" - the thread discussing the Pepper letter is "William Pepper's Letter to DoC re: NIST on WTC7" and it is currently locked by Moderators to clean up (potentially) over 100 "off topic" posts

Fair enough. Then I'll wait till that thread reopens to ask Tony and Gerry if they know of any reply by NIST so far.

 

[Animal]

Thanks, I need an internet win this morning.

Keep trying Tony. You'll get you big thread win someday.

Of course none of TS's calculations take into account changing

1)vertical displacement of the floor framing and the slab
2)axial stresses in floor beams and columns
3)in-plain strain of the floor slab
4)damage in connections
5)lateral displacement and rotation of floor beams and girders.

 

[Newtons Bit]

Remember TS previously hand waved this away.
Connection damage was typically gradual, with bolts and/or welds failing sequentially over time."
(pg 490 NIST NCSTAR 1-9)

In trooferland, every action takes place independently........allowing him to hand wave away anything that threatens his religious beliefs.

Yea, I don't even know why I bother. His arguments lack all intellectual honesty.

 

[DGM]

What are you saying buckled?

Just curious. Why do engineers waste money on such big ass bolts? Are they under any load in normal service? Should this load be consider when someone calculates what it would take to shear them from expansion due to fire?

 

[LSSBB]

The W24 x 55 beams were 53 foot (636 inch) long and that section has a moment of inertia of 29.1 in.^4 in its weak axis. Per the AISC, the modulus of elasticity of structural steel at 600 degrees C is 11,310,000 psi.

The equation for buckling force is

(Pi^2 x modulus of elasticity x moment of inertia) / unsupported length ^2

So, to buckle those beams with their shear studs broken and their temperature at 600 degrees C, the force would be

(3.14^2 x 11,310,000 x 29.1) / (636^2) = 8,030 lbs.

ASTM A325 bolts between 1/2" and 1" have a guaranteed minimum yield strength of 92,000 psi. See http://en.wikipedia.org/wiki/ASTM_A325

In a forensic analysis the rule is to multiply the guaranteed minimum by 1.1 so the yield strength would be 101,200 psi.

At 600 degrees C steel has lost about half its strength so that puts the yield strength at 50,600 psi. In shear the yield strength is 57.7% of tension and compression. So that puts the bolt shear yield strength at about 29,196 psi at a 600 degree C temperature.

The bolts were 7/8" diameter and had a shear area of 0.601 in.^2 so to shear each bolt would require

29,196 psi x 0.601 in^2 = 17,546 lbs.

To shear the six bolts at each connection would require 105,276 lbs.

Do you have a diagram of where all the forces are and where they are being applied?

 

[Tony Szamboti]

Yea, I don't even know why I bother. His arguments lack all intellectual honesty.

You have nerve questioning my intellectual honesty.

It was you who tried to say the girder would have rolled off its seat and then tried to say the fin connections wouldn't resist the relatively low moment of the girder's Cg over the distance the web was past the seat.

 

[Tony Szamboti]

Do you have a diagram of where all the forces are and where they are being applied?

Forces are assumed to act along the longitudinal axis of the expanding beams.

 

[Tony Szamboti]

Just curious. Why do engineers waste money on such big ass bolts? Are they under any load in normal service? Should this load be consider when someone calculates what it would take to shear them from expansion due to fire?

It is called vertical shear.

 

[tsig]

The girder had a 131 kip floor load and the coefficient of friction for steel on steel is about 0.2. So the total reaction force would have been about 26,000 lbs.

That would be about 5,200 lbs. per beam and doesn't even come up to the 8,000 lb. load required to buckle a slender beam at 600 degrees C, let alone the 108,000 lb. load required to break the connection bolts of each beam.

Anyone trying to say the beams buckled and/or the bolts broke doesn't have any idea and shouldn't even be commenting about it.

You sure it would still take 108,000# of force to break bolts at 600 degree C?

 

[DGM]

It is called vertical shear.

So how much does this effect your previous calculations? I know the values you quote for the bolts are no load.

 

[Newtons Bit]

You have nerve questioning my intellectual honesty.

It was you who tried to say the girder would have rolled off its seat and then tried to say the fin connections wouldn't resist the relatively low moment of the girder's Cg over the distance the web was past the seat.

No Tony, I didn't try to say that. I did say that. You are asserting that the simple shear connection will resist moment. It will not resist moments. AISC even puts this in picture format:



You assert something that is explicitly countered by modern engineering research, and then claim it's some sort of victory for you. It's pathetically dishonest to everyone who reads your garbage.

 

[Newtons Bit]

Just curious. Why do engineers waste money on such big ass bolts? Are they under any load in normal service? Should this load be consider when someone calculates what it would take to shear them from expansion due to fire?

Typically we just put one at 3" on center or so for the entire length of the web. It makes verifying connection designs easy (as they're so overdesigned for typical loads).

 

[LSSBB]

No Tony, I didn't try to say that. I did say that. You are asserting that the simple shear connection will resist moment. It will not resist moments. AISC even puts this in picture format:

[qimg]http://www.internationalskeptics.com/forums/imagehosting/thum_16329535bcc6346483.png[/qimg]

You assert something that is explicitly countered by modern engineering research, and then claim it's some sort of victory for you. It's pathetically dishonest to everyone who reads your garbage.

Now Tony, your reply should incorporate a drawing like Newtons Bit provides, and showing all the vectors of forces being applied. Don't forget forces being transferred in from other connecting parts of the structure, too.

 

[Newtons Bit]

Now Tony, your reply should incorporate a drawing like Newtons Bit provides, and showing all the vectors of forces being applied. Don't forget forces being transferred in from other connecting parts of the structure, too.

And he should also explain why various research experiments that show the above graph to be accurate are wrong.

 

[DGM]

And he should also explain why various research experiments that show the above graph to be accurate are wrong.

Because he uses his real name?

 

[Tony Szamboti]

No Tony, I didn't try to say that. I did say that. You are asserting that the simple shear connection will resist moment. It will not resist moments. AISC even puts this in picture format:

[qimg]http://www.internationalskeptics.com/forums/imagehosting/thum_16329535bcc6346483.png[/qimg]

You assert something that is explicitly countered by modern engineering research, and then claim it's some sort of victory for you. It's pathetically dishonest to everyone who reads your garbage.

Trevor, your bluster is incredible and despicable, especially in light of the fact that the image you show is not the same as the fin connection between the girder and beams.

In the case of girder A2001, the fin plates were welded to the underside of the girder top flange and the web with 5/16" fillet welds on both sides of the 4" top and 1/4" fillet welds on both sides along the 20" length. See the attachment here. It could clearly resist moments because it could react forces applied over an arm.

Your appeal to the AISC is misplaced and not accurate here. If the girder started rotating the upper weld on the fin plate would stop it. The girder's small moment if the web was past the seat would not generate anywhere near enough force to fail ten 1/4" x 4" long fillet welds in shear and then peel the ten 20" long 5/16" fillet welds on the web.

 

[Newtons Bit]

Trevor, your bluster is incredible and despicable, especially in light of the fact that the image you show is not the same as the fin connection between the girder and beams.

In the case of girder A2001, the fin plates were welded to the underside of the girder top flange and the web with 5/16" fillet welds on both sides of the 4" top and 1/4" fillet welds on both sides along the 20" length. See the attachment here. It could clearly resist moments because it could react forces applied over an arm.

Your appeal to the AISC is misplaced and not accurate here. If the girder started rotating the upper weld on the fin plate would stop it. The girder's small moment if the web was past the seat would not generate anywhere near enough force to fail ten 1/4" x 4" long fillet welds in shear and then peel the ten 20" long 5/16" fillet welds on the web.

If you would read the research, you would find that the claim of "it would clearly resist moments" has been disproved by laboratory experiments. You keep ignoring this simple fact, and it is dishonest.