26-05-2011, 12:10 PM
My own understanding of the vulnerability to a gravity driven floor collapse that could be initiated with the destruction of as few as 3 floors would indicated that as few as 12 columns could be "taken" out. These 12 columns which span 3 floors and are rather small in cross section up top would indeed be vulnerable to less than spectacular "attack.
Observations indicate the columns HAD to be destroyed up there because the ones above which conceivably could survive a sequence of collapsing floors are not seen. So the destruction which initiated the gravity driven collapse seems to have attacked columns. It might have at the same time destroyed the beam stub outlookers which secured the support channel for the core side of the floor trusses at the same time. Can't tell.
But placement would be inside the shafts or column enclosures for columns 501, 504, 505, 508, 701, 801, 1001, 1004, 1005, 1008, 708 and 807on the outlooker beam stubs.
The column splices were about 3' above the floor level... every third floor and placing a bomb or incendiary onto the beam stub from the floor level would involve two sets of 36' long columns...those above and below the device placement.
If this concept is sound it sounds like a not very complex "rigging" operation... and it might not even have required complex or sophisticatedOR precision timing or detchord. etc. If the devices were set to "go to work" at say 9:00 am -9:30... as each one destroyed a pair of columns connections (severing it from being able to transfer loads to the column below)... the other core columns would begin to take up the load of the destroyed columns.
As more and more of the 14 columns go down, more and more load is taken up by fewer and fewer remaining columns until that load exceeds their safe working load and they begin to buckle and actually it goes rather rapidly once that point is reached. Then the is a mini CD and the tower above this attack zone then descends delivering all it's mass to the level of the attack of those columns... and the floors above begin to avalanche down to the ground.
I think this could be set with little notice by anyone... especially if there was an unoccupied floor up there above 93. And if there were already access panels at these column locations who would even notice at all if workman seemed to be servicing some building system which are running vertically adjacent to the columns?
Observations indicate the columns HAD to be destroyed up there because the ones above which conceivably could survive a sequence of collapsing floors are not seen. So the destruction which initiated the gravity driven collapse seems to have attacked columns. It might have at the same time destroyed the beam stub outlookers which secured the support channel for the core side of the floor trusses at the same time. Can't tell.
But placement would be inside the shafts or column enclosures for columns 501, 504, 505, 508, 701, 801, 1001, 1004, 1005, 1008, 708 and 807on the outlooker beam stubs.
The column splices were about 3' above the floor level... every third floor and placing a bomb or incendiary onto the beam stub from the floor level would involve two sets of 36' long columns...those above and below the device placement.
If this concept is sound it sounds like a not very complex "rigging" operation... and it might not even have required complex or sophisticatedOR precision timing or detchord. etc. If the devices were set to "go to work" at say 9:00 am -9:30... as each one destroyed a pair of columns connections (severing it from being able to transfer loads to the column below)... the other core columns would begin to take up the load of the destroyed columns.
As more and more of the 14 columns go down, more and more load is taken up by fewer and fewer remaining columns until that load exceeds their safe working load and they begin to buckle and actually it goes rather rapidly once that point is reached. Then the is a mini CD and the tower above this attack zone then descends delivering all it's mass to the level of the attack of those columns... and the floors above begin to avalanche down to the ground.
I think this could be set with little notice by anyone... especially if there was an unoccupied floor up there above 93. And if there were already access panels at these column locations who would even notice at all if workman seemed to be servicing some building system which are running vertically adjacent to the columns?