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Steve, and all,
 
It seems you're asking everyone else to sit and run calculations for you that you could probably run yourself. Your question is not very precise. Are you asking for a basic physics freefall object calculation verification, comparing freefall times and the collapse times of WTC-1&2 versus WTC-7 or something else?
 
Recently I heard a 911 WTC2 survivor who happened to be NY Fire Dept official speak in Southern California about his experiences and also his perspectives from an 'engineering' standpoint. Turns out he studied Civil Engineering in college before going into the FD. However, he admitted that his CE curriculum was not in structures. Yet, he claimed that because he had done engineering calculations in college, when he saw the 2nd plane hit the tower, he knew that it was going to come down because of the kind of hit it took. Yet, he got buried and nearly killed by the falling debris sometime later. As he related it, he remembered telling himself how dumb he was to have told others to move FD equipment away from the impending collapse, and yet there he was getting caught in the mess of it. Make of it what you will, I guess his Statics 201 class must have come to his recollection as he watched the fireball of the 2nd plane some 60, 70 stories above his head. Not to slight the presentation, because it was interesting nonetheless, but I attended expecting to discuss hard engineering with a PE.
 
The single recommendation that stood out in his presentation, and he repeated it when I asked during the Q&A, was that WTC was inadequately sprinklered for a building of such size. In his opinion no skyscraper should exceed 50 stories because at that point the designers (i.e architect, engineer, builder, developer) have accepted that the loss of human life is a reasonable risk compared to the profits that will be made on such a large real estate project. Furthermore, he was emphatic in a NY kind of way to state that adequate sprinklering would only cost $2 per sf and that basically the desire for profit by the RE developer prevented it. He also claimed that the Port Authority was exempt from NY building code, and did not initially sprinkler the WTC, but retrofitted it later. He claimed the Authority was able to exempt itself out of the NY code requirements for the sake of maximum RE development. He implied that the location of stairs in the core rather than the exterior was a mistake. Pretty strong accusations I thought.
 
So if you're asking 'how do we prevent "it" in the future', what are you really asking? How do we prevent a 110 story building from collapsing from a multi-floor fire? How do we prevent a terrorist attack using jet-fuel laden planes? How do we enable occupants to safely evacuate a building that has been critically damaged? How do we address aviation security and safety? How do we protect any critical infrastructure from both man-made and natural disasters? How do we communicate to the civilian population a thorough, correct, and convincing explanation of what actually happened when this has never happened before?
 
All these questions and others can be asked in the WTC 911 scenario, and yet from a FD official, the answer was, make the buildings able to conduct survivors and rescuers safely way from fire.
 
Best

Best regards,

Thomas Honles, SE, PE
Los Angeles, CA

 
-----Original Message-----
From: ECVAl3(--nospam--at)aol.com [mailto:ECVAl3(--nospam--at)aol.com]
Sent: Thursday, September 14, 2006 10:51 AM
To: seaint(--nospam--at)seaint.org
Subject: Name-callers & Closed minds delete this email immediatley

Again I respectfully ask that anyone reading this email without an open and inquisitive mind, please exit this email and delete it. You will find it of no interest to you whereas a derogatory response or  personal attack will be unproductive and serve no purpose here.
 
I am only continuing this line because there was a glimmer of inquisition in one or two of the responses to my submittal of the web site physics911.net from the list-server. What I was hopping for was an "intelligent" (spelled correctly this time) discourse as to the structural items presented in the various reports listed on the web site such as:
 
1-Failure of structure due to pan-caking effect.
    a-WTC-7 collapsed in 6.5 sec, free-fall in a vacuum from the height of the building would be 6 sec. WTC-2 collapsed in 10  to 14 sec., (110 story building 1362 ft tall) free-fall in a vacuum is 9.2 sec.  Is this an accurate statement?
With the loss of acceleration due to the conservation of energy and conservation of momentum laws, would the pan-caking effect holdup in these time differentials? 
If not, what would be a reasonable explanation for the discrepancies?
 
have any validity or is it just smoke and mirrors?
 
These are but a few of the questions that came to my mind as I perused the site. I dismiss a lot of the statements presented without analytical backup but question whether the ones presented in an analytical manner have flaws or can be deemed to be truthful. I don't want to get into "who or why" because that debate is unproductive without the truth as to "what really happened" and how do we prevent it in the future.
 
Stephen Macie, P.E.