15-05-2011, 03:46 AM
(This post was last modified: 15-05-2011, 02:27 PM by Jeffrey Orling.)
I have no interest in Bazant's nonsense re the destruction of the twin towers.
What I explained, and you can give it the name you please... is very basic. If you provide a sufficient threshold mass which will destroy the upper most of 90 identically (structurally) designed floors... that threshold mass will not only increase with each subsequent floor destruction, but it will of course cause each successive floor below to fracture/fail. What's good for the goose is good for the goose below it.
The crush up crush down nonsense looks at the top of the tower like a monolithic structure which "attacks" another monolithic structure below which had stronger columns. This is NOT what happened and so there is no point in analyzing such an interaction. Right... we know little less massive blocks cannot destroy bigger more massive ones. Rock, paper, scissors and all that.
The gravitational part of collapse took place after the several floor masses in the region above the crash zone fractured by whatever means and descended on the "intact" floors below them and destroyed it... and so on down to the ground. This became a "gravity driven" collapse of all the floors... leaving the columns to "fend for themselves". The columns (fending for themselves) were then unable to stand absent lateral bracing and fell over... or were pushed over by the aggregating collapsing floor masses. (they didn't fend for themselves very well... they needed the help of the floors to stand tall)
Crush up and Crush down are not part of this explanation (the one which actually conforms to the observations... not some theory created from formulas. Bazant can go fly kites. He missed the boat on what happened because he is playing with equations and not observations.
There is a lesson here about how vulnerable open office column free long span office floors are to progressive collapse. THEY ARE... and any terrorists who wants to begin a ROOSD doesn't need to slam a plane into a building, but get several of the top floors to dissociate themselves from their column supports and they will take down the tower. The good news is that there are not that many long span open office column free towers out there. The bad news is that this simple truth is being withheld from the public and officials who could demand some retro fits to avoid ROOSD scenarios in susceptible structures.
What I explained, and you can give it the name you please... is very basic. If you provide a sufficient threshold mass which will destroy the upper most of 90 identically (structurally) designed floors... that threshold mass will not only increase with each subsequent floor destruction, but it will of course cause each successive floor below to fracture/fail. What's good for the goose is good for the goose below it.
The crush up crush down nonsense looks at the top of the tower like a monolithic structure which "attacks" another monolithic structure below which had stronger columns. This is NOT what happened and so there is no point in analyzing such an interaction. Right... we know little less massive blocks cannot destroy bigger more massive ones. Rock, paper, scissors and all that.
The gravitational part of collapse took place after the several floor masses in the region above the crash zone fractured by whatever means and descended on the "intact" floors below them and destroyed it... and so on down to the ground. This became a "gravity driven" collapse of all the floors... leaving the columns to "fend for themselves". The columns (fending for themselves) were then unable to stand absent lateral bracing and fell over... or were pushed over by the aggregating collapsing floor masses. (they didn't fend for themselves very well... they needed the help of the floors to stand tall)
Crush up and Crush down are not part of this explanation (the one which actually conforms to the observations... not some theory created from formulas. Bazant can go fly kites. He missed the boat on what happened because he is playing with equations and not observations.
There is a lesson here about how vulnerable open office column free long span office floors are to progressive collapse. THEY ARE... and any terrorists who wants to begin a ROOSD doesn't need to slam a plane into a building, but get several of the top floors to dissociate themselves from their column supports and they will take down the tower. The good news is that there are not that many long span open office column free towers out there. The bad news is that this simple truth is being withheld from the public and officials who could demand some retro fits to avoid ROOSD scenarios in susceptible structures.