Reply #36: I don't know about cell phones and faults ... [View All]

... and I never heard or read about them being contributors to the collapse before.

I was simply reporting that the panels at these public forums could only respond to questions from the skeptical public about fire temperatures with their estimates, but added that the duration of the fires was also just as important as the temperatures.


In hindsight and in the months since those public forums it has become interesting to me that the some of the panels also spoke about the movement and motion of the columns which is something that has also been described and discussed in these DU forums, including a link to NIST witness statements that included one man saying the building he was in was swaying.

It's also interesting to me how links to the Weidlinger report and the NIST report (quoted in message #32) refers to the "hat truss" which was also described in these DU forums.

From this it seems to me anyway that some DU forum members who have provided insight and information BEFORE Weidlinger and NIST came out actually knew what they were talking about.

That information was also much more accurate than the statement that the floor truss were only 35 feet long. The Trade Center towers were squares and the cores were rectangles. The short sides were 35 feet or so, the longer sides nearly twice that. I installed mobile aisle shelving in the Trade Center and the sections were nearly 50 feet in length. I saw the trusses several times while working at the Trade Center, and I can also remember seeing the trailers that delivered them years ago during the construction phase. They were flatbeds that had extendable sections to accomodate the 60 foot plus lengths. It is incorrect to state the truss were only 35 feet.

I also have a problem with the comments that "only" eight columns were damaged. For one, saying eight is almost the same as saying 20 percent of them, and 20% is a lot; but from my years as an ironworker I am certain that eight columns actually means more. Those 8 were connected to eight below and eight above; and by way of beams, chevrons, and other structural steel framing members to columns to the sides. Whatever happens to one affects the other. I've erected too many columns to count, and then plumbed and racked them so that they are perfectly straight up and down. We use heavy cables and turnbuckles to straighten, plumb and rack the columns before all the bolts are tightened and torqued and before the connections are welded. Turning those turnbuckles doesn't just move one column into place it moves the one above and affects ALL the other ones connected to it as well. Having 8 damaged columns actually translates to many more.

Also from my years as an ironworker I will again state that steel columns, beams and trusses are extremely sensitive to heat, even just to the sunlight. NYC is presently having sunny days with high 80 degree temperatures. Ironworkers are having some rough times with the fit and finish of structural steel framing members. Beams lying on the deck will bend or slightly curve from the sunlight and also elongate. An oldtimer ironworker will spend his day checking and marking these beams for curves so that the beam can be erected and fitted with the least amount of difficulty. He'll be checking by pulling a string from one end to another, he'll then place 1/2" shims at each end, and then he'll measure along the whole length of the beam and then mark which is the best and worst side - much the same way a carpenter will hold a board and eye it for bends and twists. Steel doesn't need much heat, the sun makes a rough job harder, and foremen do their best to get the iron hung early in the day when it's cooler to avoid headaches with fit and finish.

I can drive over an operable steel bridge everyday, but avoid it in the summer. Whenever it opens for an extended length of time to allow the passage of a tugboat and barge it elongates and can not close. The fire department has to come and spray water on it so it cools and returns to size. NYC has a subway lift bridge at the nortern tip of Broadway. They raise and lower and inspect it daily, but do so much more quickly in the summer or skip extra hot days due to heat expansion and elegation problems. The same is true at lift bridge section of the TriBorough Bridge.