not before 9-11, not since. But on 9-11 you had 3. The North tower caught fire in 1975 and burned for 3 hours, the tower never fell. Why did a fireman say on the radio, who was in one of the towers, that there were 2 pockets of fire and the he could knock them out with 2 lines of water. If the fire was so hot how could the fireman get close to a fire that could melt steel. Besides when the planes hit the towers the fire balls burned off most of the fuel. The fact that there was so much smoke shows that it was a poor fire, not hot. Days after the collapse the fires that were still burning in the basement were above 1300 degrees. Support beams that were still in the ground were cut at a 45 degree angle and edges looked like what a candle does when wax flows down them. What could cause that kind of heat?
To state that no steel framed buildings have ever collapsed due to a fire before 9/11 is akin to saying that no island had ever been completely destroyed by a bomb prior to Hiroshima.
The collapse of the WTC towers was not caused either by a conventional building fire or even solely by the concurrent multi-floor fires that day. Instead, the WTC towers collapsed because: (1) the impact of the planes severed and damaged support columns, dislodged fireproofing insulation coating the steel floor trusses and steel columns, and widely dispersed jet fuel over multiple floors; and (2) the subsequent unusually large deposit of jet-fuel ignited multi-floor fires weakened the now susceptible structural steel. No building in the United States has ever been subjected to the massive structural damage and concurrent multi-floor fires that the towers experienced on Sept. 11, 2001.
The impact was one of the largest contributing factors to the collapse which is the part of the story that conspiracy theorists like to forget when comparing these collapses with others. The impacts caused real trauma to both buildings by taking out many of the perimeter columns in the towers as shown in the picture below. The towers had a number of floors destroyed from about the perimeter columns to the core. The impact sliced the aluminum aircraft into smaller pieces but the speed of the craft also sliced through the steel like butter.
The impact brought a 500 mile an hour wind to the impact floors as a wall of debris traveled from one end of the buildings to the other. The jet fuel blast added to the event with more than just a pyrotechnic show. This high wind (debris and blast) blew the debris into the furthest corners of the building. It obviously stripped the ceiling tile system off in an instant. Photographic evidence shows no sign of ceiling tiles on the impact floors. In that same instant the all important "blown on" fire proofing was removed from the trusses and some columns. This could be seen from photographic evidence in the NIST report. The NIST also replicated the fireproofing and conditions during impact and found the fireproofing easily blew off.
In viewing these pictures of the severed perimeter columns, I do not understand how any rational person would think that explosives would have been needed to bring these buildings down. The impact from the airplanes had already accomplished what it would take several thousand of pounds of explosives to do. The fire caused by the massive amounts of jet fuel that the planes were carrying simply finished the job of weakening to the point of failure, the remaining and now overstressed steel frame. I repeat my earlier question:
Why, or for that matter how, would anyone prepare these buildings for implosion to exactly coincide with the impact of two separate 787 airliners crashing into them and why would this even be necessary?
Incidentally, on November 1, 2006 another steel framed building collapsed due to fire in Worcestershire, England. A spokesman for the fire service said the blaze had resulted in a black smoke cloud which could be seen for miles. He added: "Intense heat buckled the steel girders holding the roof."
In case you were wondering, the material burning inside of that building was toilet paper.
http://news.bbc.co.uk/2/hi/uk_news/england/hereford/worcs/6105942.stm
When the J.L. Hudson Department Store in downtown Chicago was imploded, Controlled Demolition, Inc.?s 12 person loading crew took twenty four days to place 4,118 separate charges in 1,100 locations on columns on nine levels of the complex. Over 36,000 ft of detonating cord and 4,512 non-electric delay elements were installed in CDI?s implosion initiation system, some to create the 36 primary implosion sequence and another 216 micro-delays to keep down the detonation overpressure from the 2,728 lbs of explosives which would be detonated during the demolition.
Columns weighing over 500 lb/ft, having up to 7.25 inch thick laminated steel flanges and 6 inch thick webs, defied commercially available shaped charge technology. CDI analyzed each column, determined the actual load it carried and then used cutting torches to scarf-off steel plates in order to use smaller shaped charges to cut the remaining steel. CDI wanted to keep the charges as small as possible to reduce air over pressure that could break windows in adjacent properties. At 29 floors above the street level, this remains the tallest steel framed building to have ever been demolished utilizing explosives.
http://www.controlled-demolition.com/default.asp?reqLocId=7&reqItemId=20030225133807
