Originally posted by bsbray11

It snapped due to weight and loss of rigidity.

What load was increased? What made the trusses pull so hard? Do you know how much force that would require, to yank a column out at two places simultaneously?

I'm not even going to ask how the perimeter columns could have lost strength without visibly glowing in broad daylight (which is what would have happened). You're the only one saying that anyway Esdad so I think I'll be ok.

The perimeter columns don't need to lose rigidity if they have been put into a position they have not been designed for. If it was pulled in, the load from the top would be the same, but now it would be across it rather than straight down, which is a situation it would not be designed for. So then it snaps.

Originally posted by apex
If it was pulled in, the load from the top would be the same, but now it would be across it rather than straight down, which is a situation it would not be designed for.

This has absolutely nothing to do with the diagram NIST uses, or even why columns would fail at the bolts/welds before the truss connections when the force is (apparently!) being applied directly through the truss connections and only a component of it is going towards stretching the bolts to break them, not even going to mention the spandrel plates exerting an opposite force.


Would you like to either address the diagram or explain why the truss connection wouldn't fail first, or what happens on the other side of the floor once this does happen, or how either of these relate to a pancake collapse?

[edit on 12-7-2007 by bsbray11]

Originally posted by bsbray11
This has absolutely nothing to do with the diagram NIST uses, or even why columns would fail at the bolts/welds before the truss connections when the force is (apparently!) being applied directly through the truss connections and only a component of it is going towards stretching the bolts to break them, not even going to mention the spandrel plates exerting an opposite force.

Wouldn't the bolts holding the truss to the outer wall be designed to withstand a pulling load, considering that the load would always be pulling onto it? The diagram seems to show the outer wall failing, not the bolts holding it together.

Would you like to either address the diagram or explain why the truss connection wouldn't fail first, or what happens on the other side of the floor once this does happen, or how either of these relate to a pancake collapse?

The other side of the floor? does that mean the bit attached to the core then? could that not have already collapsed?

And I didn't see an explanation of the pancake collapse anywhere anyway/

Originally posted by apex
Wouldn't the bolts holding the truss to the outer wall be designed to withstand a pulling load

No, because they were seated across the columns, not hung between them.





How sturdy does that connection look, as far as any major lateral "pulling" forces would go? (And again I ask, where does this pulling force even come from?? There WAS no dynamic initiating force according to these guys!!)

The diagram seems to show the outer wall failing, not the bolts holding it together.

And that's why we all have a problem with it from an engineering perspective.

The other side of the floor? does that mean the bit attached to the core then? could that not have already collapsed?

If it did then why do the perimeter columns just fall apart on the other side? lol

[edit on 12-7-2007 by bsbray11]

Originally posted by bsbray11

How sturdy does that connection look, as far as any major lateral "pulling" forces would go? (And again I ask, where does this pulling force even come from?? There WAS no dynamic initiating force according to these guys!!)

Ok, that image alone is pretty damn convincing, I agree it doesn't look up to holding much.

If it did then why do the perimeter columns just fall apart on the other side?

Good point, the way all round the building goes in WTC 1 does look problematic for spontaneous failures.

Originally posted by apex
Good point, the way all round the building goes in WTC 1 does look problematic for spontaneous failures.

Unless the core was taken out and the trusses (and core) actually did pull the outer facade down with it. The problem with the sagging truss theory is the core. As already established.