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(For more info on building 7 see:

After 9-11-2001,  I spent six months analyzing Building 7. The insurance companies (there were several, all of whom shared in the liability) had insurance on the contents, the building and on "business interruption".
Interestingly enough they did not have a limit on the business interruption and were paying out a million dollars a day, theoretically forever, as the building at that time was not going to be rebuilt.

The insurance companies had a meeting, and one of the members stood up and said that the damage was due to terrorists, and thus they did not have to pay out anything. The rest agreed, but realized that they would never do any business again if they held that position.

I was asked to determine how long it would take to rebuild. The insurance companies then were going to use my number to negotiate a settlement.

When Building 1 collapsed, the red brick cladding smashed into building 7.


The building caught fire. The fire department had too much on its hands, and so left the building to burn.

Floors 5 to 8 fully engaged.




Debris distribution.


The building was constructed above a Con Edison substation that had been on the site since 1967. The substation had a caisson foundation designed to carry the weight of a future building of 25 stories containing 600,000 sq ft (56,000 m2).The final design for 7 World Trade Center was for a much larger building than originally planned when the substation was built. The structural design of 7 World Trade Center therefore included a system of gravity column transfer trusses and girders, located between floors 5 and 7, to transfer loads to the smaller foundation. Existing caissons installed in 1967 were used, along with new ones, to accommodate the building. The 5th floor functioned as a structural diaphragm, providing lateral stability and distribution of loads between the new and old caissons.

A shipping and receiving ramp, which served the entire World Trade Center complex, occupied the eastern quarter of the 7 World Trade Center footprint. The building was open below the 3rd floor, providing space for truck clearance on the shipping ramp. The subway also interfered with the eastern portion of the foundation.

The spray-on fireproofing for structural steel elements was gypsum-based Monokote, which had a two-hour fire rating for steel beams, girders and trusses, and a three-hour rating for columns. Mechanical equipment was installed on floors four through seven, including 12 transformers on the 5th floor. Several emergency generators installed in the building were used by the New York City Office of Emergency Management, Salomon Smith Barney, and other tenants. In order to supply the generators, 24,000 gallons (91,000 L) of diesel fuel were stored below ground level.[16] Diesel fuel distribution components were located at ground level, up to the ninth floor.

Additionally there were two water containers for fire protection on the top floor of the building, a weight that was not trivial in the structural collapse of the structure.




World Trade Center

Buildings 1 and 2


The planes hit - the buildings did not fall (as they were properly designed not to.). Building 1 was hit at 8:46:30, Building 2 was hit at 9:03:02.

The airplane fuel burned off in a very short time. The burning fuel started fires, with desks, papers, etc. as fuel. The fires burned for an hour or so.

9:58:59. The South Tower of the World Trade Center collapses, 56 minutes after the impact of Flight 175.

10:28:22 The North Tower collapses 1 hour, 42 minutes after the impact of Flight 11

During that hour or so, between the hit and the failure, the joist connection to the external column heated up and failed, allowing the floors, one after another to fall to the floor beneath it. As I teach my class, the fewer the horizontal supports to a vertical member, the weaker it becomes. I demonstrate by placing a yardstick vertically and supporting it every inch. As the supports are removed, the yardstick eventually fails and the weight hits the ground. It does not take many horizontal supports to fail to make the millions of tons of the floors above to force the external columns to buckle and the entire building collapse.

The jet fuel (kerosene) in open air burns at  260-315C (500F to 600F). Burning wood, plastic and paper with the chimney effect of the tower will reach 1100F  to 2000F. Steel melts at around 1,370C (2500F), thus no steel would have melted. There has been one misrepresentation that has come from this. Many sites refer to the difference in the melting point of steel and the burning temperature of the resulting fire as proof that the World Trade Center could not have fallen from the aircraft fires. What those authors fail to note is that while steel melts at around 1,370C (2500F) it begins to lose its strength at a much lower temperature. The steel structure of the World Trade Center would not have to melt in order for the buildings to lose their structural integrity. Steel can be soft at 538C (1,000F) well below the burning temperature of the fires raging inside the building. Softened steel cannot resist the forces on it.

As the columns failed, the weight on top crushed the remaining structure, falling and compressing the air in the floors below. The air escaped through ducts in the side of the structure, a feature used by some irresponsibly as some sort of ignition, it was not. The speed of the descent of the building was as would be expected, not accelerated as some would try to make you believe.



A friend of mine said that it was not commercial airplanes that hit the towers, the people on those flights are on a Caribbean island and the videos show CIA airplanes hitting the buildings, or we are seeing computerized airplanes. As there are pieces of the commercial airplanes all over the site he is just not well informed. As shown above an engine, landing gears, fuselage all were found. In addition, Frank VanBrunt was one of two surveyors who found a 5-foot-long piece of twisted trailing edge flap support structure
from one of the planes that flew into the World Trade Center. It was located three blocks away from Ground Zero.  In the past, such pieces have been treated as historical artifacts. For example, the New York State Museum in Albany has in its collection a large landing gear piece that fell through the roof to the basement at the same location. It was placed there in 2002. Boeing officials told police the part came from one of its 767 airliners, but it isn't possible to determine which flight. Both hijacked planes that struck the towers, American Airlines Flight 11 and United Airlines Flight 175, were Boeing 767s.

So much for the computerized version and the not an airplane version!

The clips were at the ends of the trusses that held up the concrete floor, the stress on those clips after heating caused them to fail.




To support the controlled-demolition theory, conspiracy theorists attack the official NIST report by insisting that fire doesn't melt steel. What NIST actually does claim is that the fires were sufficient to weaken the steel to the point where they would fail - structurally.


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