'What about building 7'?

[Animal]

The 2 out of 6 bolts was an example of NISTs failure illustration method. There was zero damage to the end connections of the C79-80 girder throughout the analysis.

And once again.....the end connection are meaningless since it had buckled.

 

[DGM]

The 2 out of 6 bolts was an example of NISTs failure illustration method. There was zero damage to the end connections of the C79-80 girder throughout the analysis.

I'd find that highly unlikely due to the condition present on that day. Wouldn't you?

 

[gerrycan]

I'd find that highly unlikely due to the condition present on that day. Wouldn't you?

So at what point of the analysis would you expect to start seeing degrading of the connections at the ends of this girder (C79-80) ?

 

[jaydeehess]

In the words of Dave, "oh dear"

Explain? Has a buckled element not failed?

In this case no, because there is a particular damage pattern displayed by such elements in the analysis. eg 2 bolts fail in a 6 bolt connection = 33% damage etc. This element remains pristine at its end connections throughout the analysis.

I agree a buckled beam or girder may still support the flooring above it if that element is still connected at both ends. However its not able to do anything laterally , such as restrain the movement of the elements it is attached to. Which is what Animal and DGM seem to be trying to get you to realize.

 

[gerrycan]

I agree a buckled beam or girder may still support the flooring above it if that element is still connected at both ends. However its not able to do anything laterally , such as restrain the movement of the elements it is attached to. Which is what Animal and DGM seem to be trying to get you to realize.

Highly speculative, and when in the analysis would you expect to see degrading of the end connections in the C79-80 girder?

 

[Spanx]

Highly speculative, and when in the analysis would you expect to see degrading of the end connections in the C79-80 girder?

Why not tell us Gerry, you are the expert ?

 

[pgimeno]

Correct, we have.


On the floors directly above and below, these beams were for the most part still in place and connected, as were the corresponding girders (C79-80).
Just how strong do you think the C76-79 girder is?


What about the floors directly above and below. Wouldn't they restrain column 79?

In these floors there's damage to the connections east of the girder between 79 and 80, most likely as the result of that pushing.

And throughout all of that buckling that rendered the girder useless there was no damage to the end connections at all?

Why do I have to read the report for you?

*Read* the damn report instead of coming to me with your questions.

Girder buckling was due to the combined effects of (1) gravity loads from the floor beams, (2) lateral westward displacement due to the thermal expansion in the east floor beams, and (3) increased axial loads due to thermal expansion in the girder.
​

 

[pgimeno]

Highly speculative, and when in the analysis would you expect to see degrading of the end connections in the C79-80 girder?

Most likely after it was removed from analysis.

 

[Reactor drone]

So you believe that the model at 4H for Case B can have these 8 connections (circled) with 0% damage whilst showing a displacement of column 79 to the East due to the C76-79 girder expanding?
[qimg]http://www.internationalskeptics.com/forums/attachment.php?attachmentid=32618&stc=1&d=1425407865[/qimg]

That's what the analysis indicated. I would guess that since column 79 is only framed north south and west that when expansion of the girder between column 76 and 79 occurs it displacing column 79 to the east thereby reducing the shear forces in the bolted connections to below failure level.

 

[gerrycan]

Most likely after it was removed from analysis.

Wouldn't the stress and strain that this girder is supposedly subjected to damage the end connections at all? After all, even though it is a shorter span, why wouldn't the same kind of forces that supposedly damaged the C79-44 girder connection at C79 100% horizontally, lead to similar damage at the ends of C79-80 ? Can you envisage a scenario where there would be no damage whatsoever at the ends?

 

[gerrycan]

That's what the analysis indicated. I would guess that since column 79 is only framed north south and west that when expansion of the girder between column 76 and 79 occurs it displacing column 79 to the east thereby reducing the shear forces in the bolted connections to below failure level.

Hold on. Where exactly in the analysis are you supposing that column 79 began to move eastward by way of the C76-79 girder expanding? At 4h ? Before?

 

[Animal]

Wouldn't the stress and strain that this girder is supposedly subjected to damage the end connections at all? After all, even though it is a shorter span, why wouldn't the same kind of forces that supposedly damaged the C79-44 girder connection at C79 100% horizontally, lead to similar damage at the ends of C79-80 ? Can you envisage a scenario where there would be no damage whatsoever at the ends?

Start paying tuition if you expect an education in building structures.

 

[jaydeehess]

Highly speculative, and when in the analysis would you expect to see degrading of the end connections in the C79-80 girder?

What is "highly speculative", that a buckled girder offers no lateral restraint? " buckled" , am I reading the meaning of that word differently than you are?

Once buckled the element is not capable of contributing to the structural integrity of the system.

With col 79 failure defined as it buckling:
What do you suppose the end connections on the 79-80 girder would offer wrt heading off failure of col 79?

You also brought up the col77-80 girder and its connections. In the NIST scenario, what would these connections offer wrt heading off col 79 failure?

 

[gerrycan]

What is "highly speculative", that a buckled girder offers no lateral restraint? " buckled" , am I reading the meaning of that word differently than you are?

Once buckled the element is not capable of contributing to the structural integrity of the system.

With col 79 failure defined as it buckling:
What do you suppose the end connections on the 79-80 girder would offer wrt heading off failure of col 79?

You also brought up the col77-80 girder and its connections. In the NIST scenario, what would these connections offer wrt heading off col 79 failure?

1/ Would the C79-80 girder fail and still retain 100% integrity at each end connection to the girders?
2/ Did NIST treat the girder as failed in the above condition?

 

[jaydeehess]

Hold on. Where exactly in the analysis are you supposing that column 79 began to move eastward by way of the C76-79 girder expanding? At 4h ? Before?

Some time before girder between 79-44 walked off its seat.

What difference does it make?
A question I have asked already.

As for why connections on the south side of column 79, I would suspect those are affected by the difference in length between girder between C79-44 and the one between C79-80, and by the fact that the framing is not 90 degrees.
ETA: and by the heating scenario of the beams framing into that girder and their length.

 

[jaydeehess]

1/ Would the C79-80 girder fail and still retain 100% integrity at each end connection to the girders?
2/ Did NIST treat the girder as failed in the above condition?

You replied to my question with a question.
What is the contribution to halting col 79 failure that the connection of girder C79-80 will offer?
IMHO, that girder might as well be a rope.

 

[Animal]

Some time before girder between 79-44 walked off its seat.

What difference does it make?
A question I have asked already.

As for why connections on the south side of column 79, I would suspect those are affected by the difference in length between girder between C79-44 and the one between C79-80, and by the fact that the framing is not 90 degrees.

It just shows the ignorance of computer modeling by the troofer team.

As several have already stated......once a beam / girder buckles, it is removed from the system regardless of its connection condition. NIST even hints at that on page 490 "Prior to end connection failure, many, if not all, of the shear stud connections and failed along the floor beams due to thermal expansion effects"

 

[pgimeno]

Wouldn't the stress and strain that this girder is supposedly subjected to damage the end connections at all? After all, even though it is a shorter span, why wouldn't the same kind of forces that supposedly damaged the C79-44 girder connection at C79 100% horizontally, lead to similar damage at the ends of C79-80 ? Can you envisage a scenario where there would be no damage whatsoever at the ends?

Start paying tuition if you expect an education in building structures.

What Animal said.

NIST took into account many kinds of failure modes, including torsional. There are a bunch of ways in which connections can survive even when the girder buckles. I'll leave them up for you to discover.

 

[gerrycan]

You replied to my question with a question.

That's right, I did. We should first establish if we both agree that NIST deemed a girder to have failed in their model, despite that girder not failing in the model.

What is the contribution to halting col 79 failure that the connection of girder C79-80 will offer?

It doesn't have to. Even if the C44-79 girder has broken connections and walked, it is in reality hard up against the sideplate of C79.

IMHO, that girder might as well be a rope.

And if it were a rope, it would still be taut. But it isn't rope, it's steel, yet it remains taut and has NOT MOVED AT ALL at either end.

Not the ANSYS model, but while we're talking about rope, here's C79-44 highlighted.
https://www.youtube.com/watch?v=VQkylMIuH-g
Looks like maybe NIST did in fact model the girders as rope

 

[gerrycan]

It just shows the ignorance of computer modeling by the troofer team.

As several have already stated......once a beam / girder buckles, it is removed from the system regardless of its connection condition.

Yeah several have stated that to be the case.

NIST even hints at that on page 490 "Prior to end connection failure, many, if not all, of the shear stud connections and failed along the floor beams due to thermal expansion effects"

Yeah, NIST didn't say what several here have stated.
Well spotted.