A tip of the hat to the designers of the WTC.

[Shayna]

*Originally posted by Strainger *
**Shayna

Uhm, architects design what buildings look like. It’s the structural engineers who are responsible for making the architect’s designs actually “work.”

Damn straight. Preach it sister.**

Well, a girl’s gotta defend her daddy’s profession now, doesn’t she?

*Originally posted by Gunslinger *
*It was predictable. They could (and did) survive the impacts, but it was the fire that did 'em in. It was well known that a major fire, especially that high up, would soften the structural steel and drop the towers. **

I think we’re talking semantics here. The impacts caused the fire and the fire melted the steel, which caused the buildings to collapse. That should have been the predictable outcome of an impact from a large jet. But I won’t belabor the point, because in spite of what Robertson said at a conference (which, to me, doesn’t hold as much weight as if he’d’ve put that comment into a scientific text of some sort without evidence to back it up), you would be right that there was some predictability to the events as they unfolded.

Steeb called the collapse of the two towers “predictable,” given their structure. “They came down just like they were supposed to,” he said. “Once you get gravity involved, that’s what happens. The buildings simply implode on themselves.”

What was less predictable, he said, was how long the buildings would stand after the planes crashed into them.

“They are built to withstand 1,600-degree heat with the fireproofing,” Steeb said. “If the temperature is 900-degrees or 1,000-degrees, they should stand longer. But if they heat goes up to 2,400-degrees, you have less time. I don’t think anyone can predict how much heat was involved. I mean, an extra half-inch of fireproofing might give you an extra 30 minutes to get out of a building. It’s impossible to guess how much time they would have had with the first one. The second one might have been more predictable, given what happened with the first.”

http://www.steel.org/news/innews/pr_amm_01_0912.htm

To me, that just means that Robertson was talking out of his ass. He knew better than to say that the buildings would “remain standing,” but for some reason he didn’t elaborte after that.

[Hello_Again]

cranky, can you tell me when those talks are at the U? I’d be very interested in attending.

[jkirkman]

another view from a structural engineer:

http://www.accessatlanta.com/ajc/epaper/editions/wednesday/metro_b38a9301c2ca00fd0054.html

nothing in this that contradicts anything here–just another way of saying things.

–jack

[Omniscient]

They were built to withstand the impact of an passenger jet, but maybe not a passenger jet full of highly flammable fuel. It was the fire that did the towers in.

If it wasn’t designed to withstand the impact a fueled passenger jet, then it wasn’t designed to withstand the impact of a passenger jet. I challenge you to show me a situation where a unfueled jet could crash into a building.

Basically, if it was part of the design criteria that it should withstand the crash of a 707, then the designers fucked up, in a very big way. This is my opinion on the matter. As an engineer you don’t argue semantics when you design for these types of things. They don’t do calculations on the theoretical impact of a object weighing X lbs. at N mph, at least after undergraduate work anyways. If they were told to design the structure to withstand a situation where a plane would crash into the tower, they should design it for an impact on any floor, and to include in that analysis the fuel and subsequent fire, etc. Engineers design for real world situations, not hypotheticals.

The only out in this, is if the designers didn’t include the fact that it must resist this disaster as a design criteria, and the engineer was simply asked as a matter of a hypothetical “could it survive this”.

My thought, they fucked up, although from a cost standpoint perhaps it seemed reasonable at the time assuming it wasn’t a specific design criteria.

[Una_Persson]

*Originally posted by Omniscient *
**My thought, they fucked up, although from a cost standpoint perhaps it seemed reasonable at the time assuming it wasn’t a specific design criteria. **

Has it actually been established that being able to survive an impact from a 707 was, in fact, an actual design critera?

[rocking_chair]

if we go back to the empire plane incident, the building withstood the impact and a smaller fire than wtc. i believe that the eng.s and arch.s that spoke on the 707 impact were thinking of an empire plane incident not what happened at wtc. perhaps the team that designed the towers thought the sprinklers could handle a fire from a plane.

is the processing of jet fuel different now than when the towers were built in the 70’s?

as i stated in a thread here somewhere the struct. eng.s at the firm i work in took one look at the towers and say they would go down soon. i am glad that the building was designed to fall in on itself rather than going “timber.” or a twist and bend of the floors above the fire. how this would have looked if those towers toppled is mindboggling.