The 9/11 Forum

20% loss at 300°C? Isn't that too much? Why it seems unlikely that some of the charges made it there?

Perhaps it is... I read this someplace and don't have the attribution handy. I think that the mechanism to dislodge *charges* and send them to that corner is hard to understand... Just the corner where the engine emerged? They stopped right there.. sort of hitching a ride...???

Thoughts after reading thread:
1. Video shot from Marriott (http://www.youtube.com/watch?v=kZi4o2OBLEI) at 19:47 shows molten metal of silvery color.
2. Only part of the engine was ejected from the tower. The rest was probably jammed in the corner contributing considerable heat.
3. One post mentioned the columns as having been welded. Not what I read elsewhere some time ago (and don't have a reference). My understanding is that the welding occurred only up to a specific floor, beyong which the columns were simply bolted.

1) Hitching ride? Yes, because only the motor made it out the tower so the dislodged material ended up in that corner.

2) No, you can clearly see that teh camera has some issues with color balance

3) Those columns at floor 81 were still welded.

Please explain what was welded.

The columns were box sections and the 4 plates which made them up were welded. The spandrels were a plates as well and it was welded on the inside face of the 3 columns. The facade assemblies 3 columns and 3 spandrels in each (typical) were bolted from one to the other with splice plates between spandrels and from column to column with 4 bolts in each.

Where is the evidence that these assemblies were welded one to the other?

I mean the core column sections.

The core columns as far as I can tell were either cold rolled H sections (wide flange) or built up from plates and welded into box sections.

The connections from column to column were likely made with plates welded to each column to hold them in alignment /position until the bracing was attached. They had to make adjustments with extra plates to align the column sections since the changed to smaller ones at each 3 story level... except for the box sections which held the outside dimensions and decreased the plate thickness.

SanderO wrote:
The connections from column to column were likely made with plates welded to each column to hold them in alignment /position until the bracing was attached.

I think the box column sections were stabilized with bolts, mounted with each other via the L-brackets on every long side at their ends, before the section-to section connection was welded.

Photo of a box column weld plane (core column 608A) at the express elevator shaft 22-23, on 39th floor of 1WTC:



You can see these brackets on every single broad side of a box column. The crane support framework were also attached on core columns at these brackets and they were possibly used for lifting eyes, too.

Mr K... Thanks for posting this image... very revealing. Are you saying that the box sections had angles which were through bolted to the outside faces of the plates making up the box sections at the ends? And that these angles were used to lift the box sections into place and then bolted together? This may have been the case where there was alignment of the long faces.. or would they have used unequal leg angles? There does appear to be angles connected but I can't see if they were bolted or welded on to the face. I would guess welded... as the photos seems to show long vertical plates which would have been difficult to bolt inside the columns... and no evidence of bolt heads.

It hardly matters I would think as the cross section area of those connections would likely offer insufficient resistance to the forces of Euler buckling. Are there any images of the attachment of the lifting cables to the core box columns?