India Abroad

09-19-2003

At the halfway stage of the federally-mandated probe into the collapse of
the World Trade Center on September 11, 2001, neither Dr. Shyam Sunder nor
Dr Shankar Nair has reason to doubt the structural merits of the Twin
Towers.

Their investigations, thus far, point to a combination of uncontrollable
fires and inadequate fire-proofing as the reason for the towers collapsing.

"We have not arrived at definite conclusions yet," Dr. Sunder, lead
investigator on the National Institute of Standards and Technology probe
told India Abroad.

"But our investigation shows the weaknesses in the fire-proofing system.
The towers withstood the impact of the planes that hit them, but they
crumbled after the fire that ensued."

The 24-month, $16 million study helmed by Sunder will continue for another
year before submitting its report; the NIST, under whose aegis the study is
being conducted, is a non-regulatory agency of the Commerce Department's
Technology Administration.

As chief of the Construction and Materials Research Division at NIST, it
fell on Sunder to lead the probe into the disaster.

Sunder has, as and when required, called on the expertise of outside
experts to facilitate his probe. Thus, the contract for the analysis of the
structural system was given to Teng Associates of Chicago, with Dr. Shankar
Nair, as principal structural consultant.

Dr. Nair, grandson of former Indian foreign secretary KPS Menon, is a
senior vice president at Teng and an acknowledged expert on tall
structures.

Ironically, part of Nair's brief, as chairman of the Council on Tall
Buildings and Urban Habitat from 1997 to 2001, was to assure people of the
safety and structural solidity of tall buildings.

Nair says structural system analysis includes design, analysis, and
behavior of high-rise steel buildings, lateral (wind) and gravity systems,
connection design, structural redundancy, and load redistribution; each of
these elements has to be probed, individually and collectively, to figure
out how and why the Towers collapsed in such dramatic fashion, and within
such a seemingly short period of time.

American Airlines Flight 11 had crashed into the north tower of the WTC at
8:45 am; United Airlines Flight 175 crashed into the south tower at 9.03
am. The south tower collapsed at 9.50 a.m. and the north tower, at 10.29
a.m.

Dr. Sunder's study is limited to WTC Buildings 1 and 2 (Twin Towers) and
WTC Building 7, and will focus on the construction, the materials used and
all of the technical conditions that contributed to the WTC disaster.

The Twin Towers and WTC 7 are the only known cases of total structural
collapse in high-rise buildings where fires played a significant role;
hence, says Sunder, the study is important in the sense that it provides
previously unavailable data.

"The investigation is going well, we are getting very good co-operation
from various government agencies and the city of New York," Sunder told
India Abroad.

He believes the fires, and not the planes, caused the collapse. "If there
had been no fires after the planes hit the towers, they would have stayed.
But we cannot say for how long," he added.

Steel, Sunder points out, does not melt easily. The WTC fires were unusual,
in that temperatures reached peaks of 1,600 degree Celsius, where a typical
fire can produce temperatures touching 1,100 degree Celsius.

"What happened here was something unimaginable," Sunder says; he adds that
steel loses its strength under such intense heat; it does not burn, but it
softens, and then gravity and the sheer weight of the structure does the
rest.

The jet fuel in the planes could not, by itself, have caused the collapse.
The fuel, Sunder says, burnt out in less than ten minutes; by then,
however, it had ignited the contents of the thousands of offices housed in
the twin towers.

Sunder believes as and when the probe is completed, its findings could
result in improvements in future constructions. "But we are not a
regulatory agency," he says, making the point that his team will not
mandate any improvements. "It is for the private sector to utilize the
findings of the investigation."

Given the nature of his job, Sunder has had to make multiple visits to
Ground Zero. "Each time it was a sobering experience. Loss of human life is
sad thing."

"The investigation itself is overwhelming, there is no precedent for an
investigation, of such magnitude."

Sunder was all praise for Nair who, he said, is a noted expert on the
structural aspects of tall buildings; his probe, Sunder felt, would benefit
from Nair's expertise.

Nair for his part agreed with Sunder's assessment that the Towers were not
themselves at fault.

Lack of adequate safeguards, Nair felt, was a crucial reason. "Even now, we
don't have a sound system of fire proofing to avoid such catastrophes. So
the technology available during the construction of the towers was not up
to the mark."

Though the probe is a year from completion, Nair says on the basis of work
done thus far architects planning to construct such tall buildings in
future need to provide for improved was of evacuating inhabitants in case
of problems.

At the WTC, he points out, thousands were trapped on the upper floors; to
rectify the problem in future, exit systems should be separated from the
building proper to provide for easy escape.

Denver Rocky Mountain News

09-11-2003

MANGLED BEAMS FROM WTC TELL TALE OF HORROR BOULDER LAB EXAMINES WRECKAGE TO LEARN WHY TWIN TOWERS FELL

Each of the rusted, mangled steel beams is a historic document that tells the story of colossal destructive forces unleased two years ago in lower Manhattan.
That's how engineer Thomas Siewert views the nearly 5 tons of twisted World Trade Center steel heaped into a 4-foot-high pile on the floor of a National Institute of Standards and Technology laboratory.

It's the NIST lab's job to decode the messages locked inside the steel and to help explain why the twin 110-story towers fell on Sept. 11, 2001.
Researchers are baking and pulling apart small chunks of the steel as part of a $16 million federally funded investigation. The two-year project is about half completed, and more than 600 tests have been conducted at the Boulder lab.
The engineers select the least-damaged samples they can find, then subject them to intense heat and stresses that mimic the 767 jetliner impacts and the subsequent tower fires.
``We have collected some of the pieces with the least amount of deformation, yet the level of damage here clearly illustrates the horrific nature of the event,'' said Siewert, deputy chief of NIST's materials reliability division.
The Boulder lab has more than 30 large pieces of World Trade Center wreckage: columns, floor trusses and spandrels from both towers. Each piece bears a spray-painted number that reveals its position before the towers collapsed.
It's just a pile of scrap metal, but the sight of it triggers deep emotional responses in first-time visitors to the lab, said J. David McColskey, a NIST scientist who hand-picked much of the steel from a New Jersey junkyard.
``Any time anyone comes out here to see this for the first time, they immediately have feelings of sadness,'' McColskey said Wednesday.
Siewert ran a hand along a 4-foot section of column labeled C-65. Unimaginable forces twisted the H-shaped column into a helix. Hanging vertically from a ceiling cable, it resembles abstract art more than structural steel.
Column C-65 came from the 86th floor of the north tower. The south tower was hit by a second 767, and nearly 2,800 people died when both towers collapsed.
Some engineers immediately speculated that burning jet fuel melted the towers' steel columns, causing the collapses.
But the NIST investigation has found no evidence that temperatures in the fires reached 2,500 degrees, the melting point of steel, according to lead NIST investigator Shyam Sunder.
Some also speculated that inferior steel was the root cause of the collapses.
But the NIST tests have demonstrated that the World Trade Center steel met or exceeded design requirements, Sunder said.
``What ultimately probably contributed to the collapse was the persistence of the fires in combination with the initial damage'' from the jet impacts, he said.
``What we have to sort out is the relative roles of each,'' Sunder said.
NIST will commemorate the World Trade Center disaster this morning.
Two U.S. flags will be raised, then lowered to half-staff.
The first flag will be raised at 8:05 a.m., MDT, when the south tower collapsed.
The second flag will be raised at 8:26 a.m., when the north tower fell. The ceremony, open to the public, will take place in front of the NIST building at 325 Broadway in Boulder.