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WTC Investigators Resist Call for Collapse Visualisation
World Trade Center disaster investigators are refusing to show computer visualisations of the collapse of the Twin Towers despite calls from leading structural and fire engineers, NCE has learned.
Visualisations of collapse mechanisms are routinely used to validate the type of finite element analysis model used by the investigators.
The collapse mechanism and the role played by the hat truss at the top of the tower has been the focus of debate since the US National Institute of Standards & Technology (NIST) published its findings (NCE 22 September 2005).
NIST showed detailed computer generated visualisations of both the plane impacts and the development of fires within WTC1 and WTC2 at a recent conference at its Gaithersburg HQ. But the actual collapse mechanisms of the towers were not shown as visualisations.
University of Manchester (UK) professor of structural engineering Colin Bailey said there was a lot to be gained from visualising the structural response. “NIST should really show the visualisations, otherwise the opportunity to correlate them back to the video evidence and identify any errors in the modelling will be lost,” he said.
University of Sheffield professor Roger Plank added that visualisations of the collapses of the towers “would be a very powerful tool to promote the design code changes recommended by NIST.”
NIST told NCE this week that it did not believe there is much value in visualising quasi-static processes such as thermal response and load redistribution up to the point of global collapse initiation and has chosen not to develop such visualisations.
But it said it would ‘consider’ developing visualisations of its global structural collapse model, although its contract with the finite element analysis subcontractor was now terminated.
A leading US structural engineer said NIST had obviously devoted enormous resources to the development of the impact and fire models. “By comparison the global structural model is not as sophisticated,” he said.
“The software used has been pushed to new limits, and there have been a lot of simplifications, extrapolations and judgement calls. This doesn’t mean NIST has got it wrong in principle, but it does mean it would be hard to produce a definitive visualisation from the analysis so far.”
Then, as he reached the 22nd floor, the building shook, stairs started to heave. It sounded to Buzzelli like heavy objects were being dropped right above his head. The sound got louder, closer. He dove into a corner. “I felt the walls next to me crack and buckle on top of me,” he says. Suddenly, he seemed to be in free fall, and the walls seemed to separate and move away from him.
Maybe two hours later, he regained consciousness on a slab of concrete 180 feet below the 22nd floor. (He may be the source of the rumor that someone surfed the collapse and lived.) He was atop a hill of rubble in the midst of an endless field of rubble, smoke, and fire, sitting as if in an armchair, his feet dangling over the edge. His bag was gone. He felt numb. The air was thick with smoke and dust. He heard explosions ... For a few minutes, a raging fire drove rescuers away. ....
“That’s not in the culture of the Fire Department,” Jonas would say. “If somebody needs help, we got to give it a shot. It wasn’t a difficult decision.”
“We got to bring her with us,” he told his company.
That was when the wind started, even before the noise. “No one realizes about the wind,” says Komorowski.
The building was pancaking down from the top and, in the process, blasting air down the stairwell. The wind lifted Komorowski off his feet. “I was taking a staircase at a time,” he says, “It was a combination of me running and getting blown down.” Lim says Komorowski flew over him. Eight seconds later—that’s how long it took the building to come down—Komorowski landed three floors lower, in standing position, buried to his knees in pulverized Sheetrock and cement.
Originally posted by AgentSmith
But I thought there were 'massive explosions' in the basements? If this is accurate and they were to destroy the support columns, then how come they obviously didn't? So now these explosions weren't in the basement anymore but over 22 floors up? please...
The buildings plainly did not withstand jet impacts, the elusive clue being given away by their stark absence from the New York Skyline.
The aircraft impacts consisted of the impacts themselves and the fires that followed. As the article state not only were the calculations (if done) based on a lesser aircraft, but also one which was travelling much slower and did not take into account the fires afterwards.
I also do not see how the survivors condradict the theory of a collapse from the top down as claimed, they do however contest the theory of explosives in basements.
Didn't you ever play the game where you stack building blocks up and take turns poking them out until the building gives when you were a kid? It might have helped you understand.
Matthys Levy, co-author of a controversial study on why the World Trade Center collapsed in the aftermath of the Sept. 11 terrorist attack, will present his findings as part of a public regional symposium sponsored by the National Academy of Engineering on April 10 at CU-Boulder.
The symposium, "Tall Buildings: Are They Safe Enough?" will be held from 2 p.m. to 5:30 p.m. in the new Discovery Learning Center at CU-Boulder's College of Engineering and Applied Science. The Discovery Learning Center is located on the southwest corner of Colorado Avenue and Regent Drive.
Levy, a principal in the civil engineering consulting firm Weidlinger Associates, is scheduled to present "Anatomy of a Disaster: The World Trade Center Investigation" at 4 p.m. His half-hour talk will include a presentation of the computer simulation Weidlinger Associates developed to depict the sequence of failures leading to the collapse of both towers.
The firm's analysis found no structural flaw in the building's design but concluded that fire weakened the vertical steel support columns so that they were unable to hold the weight of the floors above. Weidlinger's findings contradict the results of the initial federal investigation performed by the Federal Emergency Management Administration, which concluded that unconventional floor supports failed, leading to a progressive collapse of the buildings.
Originally posted by LaBTop
Especially this text doesn't fit my believe of the cause of that "wind" :
"The building was pancaking down from the top and, in the process, blasting air down the stairwell" and especially this remark "even before the noise".
Stone Phillips: “And when you say, that’s when everything hit. What happened?”
Richie Picciotto: “The noise started again.”
Mike Meldrum: “You heard the rumble. You could feel the rumble.”
Their tower was now disintegrating. Hundreds of thousands of tons of cement, steel, and glass began to melt away. And Ladder 6 was still in the stairwell.
Matt Komorowski: “The first thing I really felt was the incredible rush of air at my back. And maybe I felt it before everybody else, because I was the last guy.”
Stone Phillips: “Like a gust of wind, behind you.”
Matt Komorowski: “Gust of wind. Wind tunnel. It was the most incredible push at your back, that you can feel.”
Stone Phillips: “A rumbling sound, this gust of wind? And then what happened?”
That was when the wind started, even before the noise. “No one realizes about the wind,” says Komorowski.
FWIW< as to the claim that the core was completely destroyed at the base of the building. 16 people survived in stairwell b of the north tower. They were located at around the 5th floor and wound up on three.
thermite reactions, etc...all of which has been covered in several other threads, and which for some unexplained reason...some of the same people keep bringing these up despite them knowing they have been debunked in other threads...
So how can the locals on this forum, or anyone for that matter, even begin to make assertions without proper information?
"These towers were build to take the impacts of hitting Boeing 707's, comparable to Boeing 767's".
Again.. this guy doesn't have a clue, and did no research:
707 Max. weight= 336,000 lb ...... Fuel Capacity= 11,500 U.S. gal
767 Max. weight= 450.000 lb ...... Fuel Capacity= 23,980 U.S. gal
NIST NCSTAR 1-3: Mechanical and Metallurgical Analysis of Structural Steel - p43
Only three locations had evidence that the steel reached temperatures above 250C. These areas were:
* WTC1, east face, floor 98, column 210, inner web.
* WTC1, east face, floor 92, column 236, inner web.
* WTC1, north face, floor 98, column 143, floor truss connector.
Other forensic evidence indicates that the last example probably occurred in the debris pile after collapse.
Similar results, i.e. limited exposure if any above 250C, were found for the two core columns recovered from the fire-affected floors of the towers, which had adequate paint for analysis.
Originally posted by HowardRoark
His assessment agrees with the NIST findings.
No demolition charges.
"If you've seen many of the managed demolitions where they implode a building and they cause it to essentially to fall vertically because they cause all of the vertical columns to fail simultaneously, that's exactly what it looked like and that's what happened"
It was a picture perfect day in September. I was watering some plants on my terrace and enjoying the unseasonably warm weather when I heard the sound of a plane flying low. Within seconds I watched in horror as the unthinkable unfolded, right in my backyard!
The shock was overwhelming. My first thoughts was that it was a terrorist attack. This was confirmed by the news reports of Al Qaeda. But one thing the reporters left out was something I witnessed first hand. A very important omission at that!
Seconds before the South Tower crumbled to its doom, I heard/felt a series of explosions. Same with the North Tower. There was no denying it, I could FEEL the vibrations of them like a small earthquake. Yet when I turned on the news none of the other eyewitnesses commented on this.
Indeed, in the days that followed, like many Americans, I remained glued to the news networks to keep myself informed of any developments and confirm what I had witnessed. But despite the numerous eyewitness accounts, there was still no mention of the explosions.
I decided to examine the evidence for myself…
Originally posted by MacMerdin
Does anyone have the demo version of SAP2000? I'm trying to download it but can't get it to download correctly because their site is down....I've spoken with their customer support. It would be great to get the original zip file so I can unzip it and use it on my computer for the full 30 days. Thanks......or if anyone knows where I can download it other than from comp-engineering.com.
Originally posted by billybob
here is a story from a photographer who accidently ended up in a funny fly on the wall kind of place. VERY interesting stuff (of course, he just made it up, right smith, dib, roark?)
9-11: secret RESEARCH TEAM disbanded in 1988 seeking ways to cheaply remove WTCs
Originally posted by zappafan1
This entire thing has shown that there are thos who have way too much time on their hands... possibly because they don't have jobs? In some cases, I'm sure.