Rebuilding Ground Zero

“Via what mechanism is such load-sharing supposed to take place?”

It not only is “supposed to take place”, it does take place (in most high-rise buildings), because the horizontal-beam components, upon which the weight of the floor rests, are not just tied to each other and to the columns on the perimeter-external wall, and the core, they are, at various points in their horizontal structure, tied to the many intervening vertical columns between the vertical columns on the perimeter-external wall and the core.

The weight-load of the floor is thus spread/carried, collectively by all the vertical columns. Because there are multiple such vertical columns, between the perimeter-external wall and the core, there could be a small number of failures at a number of individual vertical columns, at the perimeter-external wall, or in-between the external-wall and the core, and the weight-load of the floor would still be supportable, with all the intervening and surrounding vertical columns carrying the additional weight of the floor that is no longer supported by the few damaged vertical columns (or damaged connection of the horizontal-beams to the vertical columns) under that particular floor.

The WTC towers had no such intervening columns between the perimeter-external wall and the core. The horizontal-matrix under the floor is capable of remaining rigid, across the totality of the floor, if it is not itself damaged. But, it is not capable of remaining at the same position, vertically, across it’s entire expanse, if too much of it’s weight no longer has connection to too much of the vertical supports.

The more the number of such vertical support points there are in the structure, the less weight needed to be “carried” independently by any one vertical column. This same principal can apply along any horizontal axis of the floor. But, in the case of the WTC, there was nothing that supplied primary vertical support between the perimeter-external wall and the core - nothing that would help, temporarily, carry the weight-load of the floor if vertical support failure occurred at the external wall and the core.

In a conventional building the loss of too much of that vertical support - to a floor at the position it is at, vertically - by which a floor would “drop”, requires damage to connections to many vertical columns between the external wall and the core, because there are many vertical columns that can temporarily carry the load displaced to them from a few that are damaged.

The WTC had primary vertical support for the floor-sub-structure at only two general areas - the vertical columns at the perimeter-external wall and the core. The attack damage and the fire damage, together created breaks, heat-stress and disconnections to some of both areas (the subfloor’s connections to vertical support) for the floors that received the direct hit.

Without any intervening vertical columns - between the core and the external wall, the weight-load for the sub-floor areas with there direct connections to vertical support dam aged meant that their weight-load was transferred along both horizontal axis to where-ever remaining vertical support still held - which, again, at the WTC could only be at the perimeter-external wall and the core (nothing was in-between).

You can see this load-shift/transfer to the vertical supports at the perimeter-external wall, in the last few seconds just before the collapse begins, in the form of wave-motion beginning just at and under the most-damaged floor and spreading upward.

The undamaged vertical columns at that point are trying to respond to the weight-load being transferred to them from the horizontal sub-floor structure. It must be transferred to them because where that structure no-longer has vertical support, it must either fall, or achieve its present position, by transferring the load horizontally to other perimeter-external columns or the core. But, at that point heat-stress had also begun to damage some connections of the horizontal-sub-floor structure at their points of connection to the core. At that point, you then had some (apparently too much) weight of a damaged floor no longer tied to vertical support at the only two vertical support areas - the perimeter external wall and the core.

That’s when the “pancake” affect began, with each floor that “dropped” adding its weight to the total weight load needing vertical support under it and ripping at the core as it “fell” - in other words, the weight load requirement became 2x, 3x, 4x, etc, as one, two, three floors , etc dropped onto the “next” floor.

Personal experience of a friend of mine witnessed the logarithmic scale of the increasing weight-load of the “pancake” - as he described the sound as similar to a monstrous freight-train careening off of its tracks at a constantly increasing rate of speed - he could hear the rate of the fall increase as it proceeded (he was there, escaping to a distance of a couple blocks from the building before the fall).

“The Empire State Building was hit by a much smaller airplane; the body of the plane hit at floor level, where the building was strongest, and yet still did considerable damage.”

It didn’t cause the building to collapse.

“Someone who was deliberate aiming a 767 to produce maximum damage could probably have caused the Empire State Building to topple instantly.”

I believe that result could only be achieved if it managed to hit the building at a very low point of entry, possibly. I believe if it hit high on the building it would most likely “lob-off” a section of the building at and above its point of entry.

From one side of the building (at the Empire state building) to another side of the building, there is more mass per-floor-per square foot, than there was at the WTC (many more intervening columns of steel and cement between the external wall and the core). I think the additional columns and mass would hold long enough to cause the falling weight above the damage to topple-over, because the support requirement is spread across a larger number of support points, each with a certain amount of mass of its own. The mass of the vertical support at the WTC existed only at the external wall and the core, requiring structural damage only at those two areas - because there was no great amount of vertical supporting structure between them.

“Unlike the WTC, whose walls had a substantial ability to carry loads upward and diagonally downward (so that the areas above the crash site remained supported), most buildings have essentially zero ability to shift loads.”

Not only did the WTC have greater ability to “carry loads upward and diagonally downward” in its lone-set of external perimeter vertical columns, those external-perimeter vertical columns were REQUIRED to have that greater ability due specifically to the absence of the many intervening vertical columns - that most high-rise buildings have - in which some of the load could be transferred. And, thus at the point just before the collapse, you see the affect of those external-perimeter vertical columns attempting to compensate for the load shifting, as they begin a wave motion. In a conventional high-rise, some of that requirement would have been absorbed by the vertical columns (that go to bed-rock) spread throughout the interior of the building, muting the lateral affect across a number of vertical support points, not just at the external wall.

“Knocking out even one column can have a major impact on a building; it will usually stand, but often be damaged to the point of being permanently uninhabitable. Knocking out two or more columns will be even worse.”

You said it. Damaged, not knocked down.

“RICK RESCORLA immediatley told the NY Port Authority that they would be hit with explosives in the basement by Muslim Fundamentalist extremists. He was told to mind his own business, which he promptly did by training his 3,000 employees to quickly evacuate after a coming terrorist attack.”

And the record of this is where??

“During the 1993 terrorist bombing attack in the World Trade Center basement, he became famously known as ‘The Last Man Out’ for his making sure everyone else got outta there first on that Day of Infamy. After which he predicted a Terrorist Attack from the Air. Getting the same response he had previously received from the Port Authority.

And the record of this is where??

“In 1999 CBS Television aired a TV Interview of RICK RESCORLA, taped in his own World Trade Center office with Tower I standing in the background. A TV Interview in which he predicted his own future demise at the hands of Muslim Fundamentalist extremists.”

Where is a link or a transcript???

“To win at war, one must first know one’s Enemy. RICK RESCORLA was predicting who that Enemy was going to be in our next World War.”

Sorry, he only understood “who” they were; a fact which had been plain to any informed individual since the 1983 suicide bombing of our marines in 1983, so certainly not a unique understanding on his part. And, further, by his own statements he showed no understanding of WHY they acted as they did, what was actually behind their Islamic fundamentalism and why they would be a threat to us NO MATTER WHAT THE U.S. DID ANYWHERE.

“After which he predicted a Terrorist Attack from the Air. Getting the same response he had previously received from the Port Authority.”

And the record of this “prediction” is where??

Mr. Recorla did not even understand the Vietnam War he fought it. The Tet offensive was a disaster for the North, not a victory, and the Viet-Cong were not an indigenous South-Vietnamese force fighting along-side their northern “brothers” but the hired political and terrorist wing of a totally northern Vietnamese political movement.

The war was never “won” on any battlefield in Vietnam by the north, it was won for the north here in the United States by the American communist led “anti-war” movement. Even the north’s great general, Giap, who the ignorant Mr. Rescola said we should have somehow “backed”, admitted in his personal biography that had it not been for the anti-war movement led here by people like John Kerry, the north would have been forced to quit and quit their use of the terrorist hand-maidens, the Viet Cong against the south. Even after the “peace” treaty, the north had not “won”, and only after the traitorous Dims cut off military aid to the south did the north “succeed” and not via the Viet-cong, but by the full-scale invasion with all their divisions - the invasion our presence had always prevented. Of course that invasion violated the treaty in which the south was to have been left in peace by the north, but Carter and his ilk could have cared less.

Even in Cambodia, the leadership of the Khemer Rouge, of which the current Cambodian Prime Minister was a member (before he defected) thought that they would always been at most a rural “resistance” movement, but never the reigning power in the country, because they did not believe they could successfully counter the western supported government and that the west would continue its support. Little did they know, that out own traitors had something else in mind - something else, for which they would not even raise much of stink about the killing fields, which they, the Democrats produced by the giving the Khemer Rouge the one thing they needed - government in Cambodia cut-off from western military aid.

Similarly, Mr. Rescola, in his blame America from Islamic terrorist ideology, had as little idea or understanding of WHY our enemies act as they do now, as he did about the North Vietnamese.

Most of the floor weight is indeed borne by colums (that's what the columns are there for), but that doesn't imply the columns are capable of sharing loads. Generally, the only thing capable of supprting the floor near any particular column or the portion of a column just above a floor, is the portion of the column below that floor. Floors are designed to be supported by columns--not vice versa. Knock out a portion of a column on e.g. the 50th floor, and everything directly above that will be essentially unsupported.

The exact effect of knocking down multiple columns would depend upon which columns they were, and upon how the structure of the building was designed to handle lateral loads. In many buildings, most of the support columns have essentially zero ability to handle lateral loading; rather, the floors tie all of the columns to some structure or structures which are built to withstand lateral loads. Kill the floor between a column and its lateral support, and that column will fail.

Thank you for your interest, Wuli.

The source questions you are asking about 9/11 Lifesaver RICK RESCORLA are to be found in the http://www.RickRescorla.com Links I previously sent you in my ALOHA RONNIE Post No. 36 and in his best seller Biography titled:

..’HEART of a SOLDIER’.. by JAMES B. STEWART

Also in the various 9/11 TV Specials about RICK’s heroic life and death. Starting with a March 2002 ‘Dateline NBC’ RICK RESCORLA Segment that starts out with his fellow 7th Cavalrymen’s IA DRANG-1965 Veterans Day Weekend dawn ceremony at the 3rd Panel of the Vietnam Wall in Washington, D.C. held in his honor.

You are very perceptive in your analysis about the Vietnam War.
Bears some repeating in this new time of war with our own Freedom directly at stake right here at home, perhaps..?

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