The statement that structural engineers were surprised
when the towers collapsed, doesn't mean that they agree with steve e jones or you today. Most professional magicians enjoy watching other magicians work, because they still get surprised. They do not throw all of their knowledge of human perception out the door and start believing in supernatural magic. They can usually figure out the trick eventually.
The
pbs link you supplied to show that most(58%?) structural engineers were surprised when the towers fell has
19 other items. Which of them support steve e jones?
Let's look at these few specifically:
8. Temperatures of the fuel fire may have reached 2,000°F.9. Though no evidence has turned up that the fires burned hot enough to melt any of the steel, eventually the steel lost 80 percent of its strength because of the intensity of the fire.*10. While there are signs that the fire melted aluminum from the fuselage or wings of at least one of the planes, there is no evidence that the aluminum burned.11. Many structural engineers feel the weak link in the chain within the towers was the angle clips that held the floor trusses between the interior and exterior steel columns.12. The angle clips were smaller pieces of steel than the columns and therefore gave out first.13. Each floor was designed to support approximately 1,300 tons beyond its own weight, but when one or more gave way in the intense fire of the impact zone, the combined weight of higher floors crashing down reached into the tens of thousands of tons.I can't understand why you bothered to post the NOVA link as supposed support of your argument.
Moving on, take the time to read these first few links I found on the "structural engineer" issue:
CHICAGO, Illinois, September 11, 2001 - According to one of the designers of the World Trade Center (WTC), the towers were originally designed to take the impact of a Boeing 707; and the impact of the aircraft this morning did not take the buildings down. In fact, WTC One stood for 1 hour and WTC Two stood for 1 3/4 hours after impact. Engineers familiar with the chain of events suspect that heat from the massive and extraordinary fires weakened the structures and initiated the progressive collapses.
www.caddigest.com/subjects/wtc/select/ncsea.htm
Stanford Report, December 3, 2001
Structural engineer describes collapse of the World Trade Center towers
BY MARK SHWARTZ
Vulnerabilities in the design of New York's World Trade Center (WTC) are likely to have contributed to the collapse of its two main towers and adjacent buildings, according to Ronald O. Hamburger, a structural engineer currently investigating the Sept. 11 disaster.
"These buildings were incredibly strong, especially with respect to resisting dead loads and wind loads, but they also had a number of vulnerabilities," Hamburger told a packed auditorium on Nov. 29 when he delivered the second John A. Blume Distinguished Lecture -- an annual event sponsored by Stanford's Blume Earthquake Engineering Center.
http://news-service.stanford.edu/news/2001/december5/wtc-125.html
Founded in 1852, ASCE represents more than 125,000 civil engineers worldwide
and is the country’s oldest national engineering society. ASCE members represent the
profession most responsible for the nation’s built environment. Our members work in
consulting, contracting, industry, government and academia. In addition to developing
guideline documents, state-of-the-art reports, and a multitude of different journals,
ASCE, an American National Standards Institute (ANSI) approved standards developer,
establishes standards of practice such as the document known as ASCE 7 which
provides minimum design loads for buildings and other structures. ASCE 7 is used
internationally and is referenced in all of our nation’s major model building codes.
The events of following the attacks in New York City were among the worst
building disasters and resulted in the largest loss of life from any single building event in
the United States. Of the 58,000 people estimated to be at the WTC Complex, over
3,000 lives were lost that day, including 343 emergency responders. Two commercial
airliners were hijacked, and each was flown into one of the two 110-story towers. The
structural damage sustained by each tower from the impact, combined with the ensuing
fires, resulted in the total collapse of each building. As the towers collapsed, massive
debris clouds, consisting of crushed and broken building components, fell onto and blew
into surrounding structures, causing extensive collateral damage and, in some cases,
igniting additional fires and causing additional collapses. In total, 10 major buildings
experienced partial or total collapse and 30 million square feet of commercial office
space was removed from service, of which 12 million belonged to the WTC complex.
www.asce.org/pdf/5-1-02wtc_testimony.pdf
The performance last week of the World Trade Center towers receives a top
grade from Jon Magnusson, chairman and chief executive of Seattle-based
Skilling Ward Magnusson Barkshire Inc. His firm is one of two successor
agencies to the firm that served as the original structural engineering consultants
for the World Trade Center.
Although he couldn't confirm the widely reported assertion that the buildings
were built to withstand the impact of a Boeing 707, Mr. Magnusson contends
that they withstood the impact of an even larger plane. The critical damage, he
contends, came from the subsequent fire.
www.absconsulting.com/news/wsjsept11.pdf
Of course, you don't need an engineer to tell you why the towers fell down: two Boeing 767s, travelling at hundreds of miles an hour, and carrying more than ten thousand gallons of jet fuel each (if you converted the energy in the Oklahoma City bomb into jet fuel, it would amount to only fifty-one gallons), crashed into the north and south buildings at 8:45 A.M. and 9:06 A.M., respectively, causing them to fall--the south tower at 9:59 A.M. and the north tower at ten-twenty-eight. Nor do we need a government panel to tell us that the best way to protect tall buildings is to keep airplanes out of them. Nevertheless, there is considerable debate among experts about precisely what order of events precipitated the collapse of each building, and whether the order was the same in both towers. Did the connections between the floors and the columns give way first or did the vertical supports that remained after the impact lose strength in the fire, and, if so, did the exterior columns or the core columns give way first?
www.booknoise.net/johnseabrook/stories/technology/tower/
As the joists on one or two of the most heavily burned floors gave way and the outer box columns began to bow outward, the floors above them also fell. The floor below (with its 1,300 t design capacity) could not support the roughly 45,000 t of ten floors (or more) above crashing down on these angle clips. This started the domino effect that caused the buildings to collapse within ten seconds, hitting bottom with an estimated speed of 200 km per hour. If it had been free fall, with no restraint, the collapse would have only taken eight seconds and would have impacted at 300 km/h.1 It has been suggested that it was fortunate that the WTC did not tip over onto other buildings surrounding the area. There are several points that should be made. First, the building is not solid; it is 95 percent air and, hence, can implode onto itself. Second, there is no lateral load, even the impact of a speeding aircraft, which is sufficient to move the center of gravity one hundred feet to the side such that it is not within the base footprint of the structure. Third, given the near free-fall collapse, there was insufficient time for portions to attain significant lateral velocity. To summarize all of these points, a 500,000 t structure has too much inertia to fall in any direction other than nearly straight down.
www.tms.org/pubs/journals/JOM/0112/Eagar/Eagar-0112.html
*No evidence has turned up that steel melted.
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