Originally posted by TrickoftheShade
reply to post by Agent_USA_Supporter
From your source:
The strength of the towers was enormous but they would not have been designed for aircraft strikes
The towers themselves were built strong. They had to be to withstand the strong winds from frequent severe storms that pass the area. A white paper
released on February 3, 1964 states that the Towers could have withstood impacts of jetliners travelling at 600 mph , this speed is of course greater
than the impact speed of either of the jetliners used on September 11. The original study mentions that the building could withstand the impact of
a 707 with a full fuel load. The Boeing 767-200s used on September 11 were only slightly larger than the anticipated impact by a 707 or DC 8 the
World Trade Center's designers prepared for. Interestingly the 707, although a fraction smaller than the 767, actually has a faster cruising speed
than the 767.
Boeing 707-320: cruise speed 607 mph
Boeing 767-200: cruise speed 530 mph
FEMA (Federal Emergency Management Agency) released its official report in 2002. In Chapter 1 of the report appears a graphic which accurately
compares the size and impact damage on a large building caused by a 707 and a 767. The graphic is revealing because it shows that a 707 actually
impacts slightly further than a 767. This is because a 707 retains a greater kinetic energy due to its size and travelling speed. Interestingly the
two types of aircraft both share a similar fuel capacity but on September 11 both 767’s were only carrying 10,000 gallons of fuel which is about 40%
of the total capacity of a 707. What this means is that the towers were designed to withstand greater impacts than those witnessed on 9/11.
The above mentioned white paper released in 1964 states candidly:
“The buildings have been investigated and found to be safe in an assumed collision with a large jet airliner (Boeing 707—DC 8) traveling at 600
miles per hour. Analysis indicates that such collision would result in only local damage which could not cause collapse or substantial damage to the
building and would not endanger the lives and safety of occupants not in the immediate area of impact.”
source: James Glanz and Eric Lipton City in the Sky: The Rise and Fall of the World Trade Center, Times Books, Henry Hold and Company, LLC, 2003, page
John Skilling, head structural engineer for the World Trade Center, confirmed the strength of the towers in a 1993 interview:
“Our analysis indicated the biggest problem would be the fact that all the fuel (from the airplane) would dump into the building. There would be a
horrendous fire. A lot of people would be killed... The building structure would still be there.”
That the towers were designed to withstand impact by airplanes should come as no surprise, in fact the towers were over-engineered to cope with a
variety of emergency scenarios. This is not unique to the construction of the towers but is actually standard practice. [source: Factor of safety,
StateMaster.com, [cached: 911research.wtc7.net...
Massive structures must typically be over-engineered to withstand five times the anticipated static load and three times the anticipated dynamic load.
The 1964 white paper confirms this over-engineering and further insists that the towers would survive 100 plus mile winds even if all the perimeter
columns on one face and some of the columns on each adjacent face were missing. This incredible over-engineering was confirmed by John Skilling who
told Engineering News Record in 1964 that:
“…live loads on these [perimeter] columns can be increased more than 2000% before failure occurs.”
source: How Columns Will Be Designed for 110-Story Buildings, ENR, 4/2/1964
On January 25, 2001 construction manager for the World Trade Center, Frank A. Demartini, told a television interviewer:
“The building was designed to have a fully loaded 707 crash into it. That was the largest plane at the time. I believe that the building probably
could sustain multiple impacts of jetliners because this structure is like the mosquito netting on your screen door - this intense grid - and the jet
plane is just a pencil puncturing that screen netting. It really does nothing to the screen netting.”
These are not the remarks of inexperienced observers. Demartini for example was an architect first hired by Leslie E. Robertson Associates to examine
the damage from the 1993 World Trade Center bombing. His office was on the 88th floor of the North Tower and he was killed during the attacks of
September 11, 2001.