My incorrect analysis of a foundation photo does not create "steel core columns". You still have no image of the supposed steel core columns inthe core area and no independently verified evidence of them.
images of the steel core columns in the core area.
independently verified by
"For a combination of historical, cultural and economic reasons, tall, concrete-core buildings dedicated to office use are unusual in New York, where builders prefer the wallboard-enclosed cores with steel frames that Mr. Robertson pioneered in the trade center."
New York Timeshere
verified by....
"Engineers are still debating whether the Twin Towers' unique structure should be credited for surviving the initial crashes, or blamed for collapsing in the subsequent fires, or both. But the point is that it was unique, utilizing closely spaced columns connected to a steel core by relatively lightweight floor trusses. "
Newsweek.
Newsweek.com
verified by....
"Each of the towers, more than 200 ft. wide on each side, contained a central steel core surrounded by open office space. Eighteen-inch steel tubes ran vertically along the outside, providing much of the support for the building"
Time Magazine.TIME.com
verified by....
"The twin towers were the first supertall buildings designed without any masonry. Worried that the intense air pressure created by the building's high speed elevators might buckle conventional shafts, engineers designed a solution using a drywall system fixed to the reinforced steel core. "
engineering.comENGINEERING.com
verified by....
"Like many high-rises built in the 1960s, the Twin Towers were constructed with their weight distributed between a hollow steel core (containing services like elevators) and steel columns around the perimeter, maximizing open floor space. Many believe the older high-rise design, in which steel columns are often encased in concrete, is more fire resistant.
“A lot of people have told me, ‘You should have used more concrete in the structure,’” said Robertson. However, his chart plotting the strength of steel vs. concrete at various temperatures showed that at the incendiary levels that raged in the towers, the two materials become similarly weak."
Berkeley 04.17.2002 - World Trade Center remembered
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"Yamasaki has switched from concrete, his favorite medium, to steel because of the sheer height of the towers, and instead of having the weight of the structure carried by the frame and the elevator core, the great steel columns of the exterior walls will support it."
Time Magazine article from 1964!!
Art: Onward & Upward - TIME
so now that we have that out of the way.... where are your pictures of the concrete core? ANY picture of it?
