Trusses bent in 1975 World Trade Center fire

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It states here that in 1975, there was truss buckling that needed to be repaired after a fire that lasted more than 3 hours. Realize however, the fire raged on less than 25% of one floor, though it spread to over 6 through utility closets. Now, multiple floors that we know were engulfed across the entire building, and we are to beleive that there was no buckling or loss of support.

Additionally, on February 14, 1975 a major fire occurred, the result of arson, which began on the 11th floor of the north tower during the middle of the night. Spreading through floor openings in the utility closets, it caused damage from the 10th to 19th floors, though this was generally confined to the utility closets. However, on the 11th floor about 9,000 square feet was damaged. This was about 21 percent of the floor’s total area (43,200 square feet) and took weeks to repair. Some parts of the steel trusses (floor supports) buckled due to the heat. 132 firefighters were called to the tower in response, and because the fire was so hot, many got their necks and ears burned. Fire Department Captain Harold Kull described the three-hour effort to extinguish it as “like fighting a blowtorch.” [WTC Environmental Assessment Working Group, 9/2002, pp. 10 ; New York Times, 5/8/2003; Glanz and Lipton, 2004, pp. 213, 214, 324; Kuligowski, Evans, and Peacock, 9/2005, pp. 1] An article in Fire Engineering magazine will later summarize, “[A]lmost all large buildings will be the location for a major fire in their useful life. No major high-rise building has ever collapsed from fire. The WTC was the location for such a fire in 1975; however, the building survived with minor damage and was repaired and returned to service.” [Fire Engineering, 10/2002] Building 7 of the WTC, which completely collapses late in the afternoon on 9/11, has also suffered a ‘significant’ fire in 1988, occurring on its third floor, with multiple sprinklers being activated.

This is a pretty good article that shows that the steel in the WTC, almost 30 years earlier, buckled under a much smaller fire.

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