Professionals and other observers have already begun the necessary discussion of whether the structural performance of the World Trade Center towers should be applauded, because their initial resistance to tremendous impacts and accelerated fires allowed tens of thousands to escape, or criticized, because their sudden total collapse killed thousands more.
Experts are widely quoted as suggesting the collapse of the towers was inevitable — even though clearly not expected by the New York Fire Department. Wider speculation has come from structural experts and less authoritative observers.
From the time each was hit by an almost fully fueled hijacked 767 commercial jet, the south tower stood for 56 minutes, and the north tower stood for one hour and 40 minutes. Explanations of the resistance of the buildings point to standard fireproofing treatments and structural safety factors eventually overwhelmed by unexpectedly high temperatures.
Discussion of the building failures point to the loss of many who had survived the initial impact, and the historical statement of the original designers that they had designed in anticipation of the impact of a 707 jet airliner. Speculative critiques point to weaknesses in the perimeter columns, the floor systems, the internal core, possibly vulnerable shear connections between floors and core, a lack of internal columns between floors, and an overall lightweight, intentionally minimalist structural system.
The horrible power of "progressive collapse," in which the weight of some floors falling causes the floors below to fail as well, has been discussed by demolition experts and people of the street. Further speculation has concerned the adequacy of the fire suppression system, the fireproofing of structural steel, and the exiting stairwells.
It is extremely important to understand both the success and failure of these towers under extreme stress, partly to assuage a collective need to understand, partly as matter of forensic crime scene reconstruction, but most importantly to help the design professions create safer building codes and highrise buildings in the future.
Many of the theories now being offered contradict each other. No one has the necessary data yet to reach responsible professional conclusions regarding specific failure modes in the World Trade Center structures. Real answers can only come after a great deal of painstaking research, followed by calm, impartial, and in-depth structural analysis. Until investigation and analysis is complete, it will remain premature to make judgments about the causes of the collapse.
The issues are currently under investigation by the American Institute of Steel Construction (AISC), the Structural Engineering Institute of the American Society of Civil Engineers (ASCE), and others. In future issues, ArchitectureWeek will report on substantial findings.
An Architect in New York
For one architect who lives in Greenwich Village, a mile and a half from the New York disaster site, the recovery involves mourning both lost people and lost buildings. James Brogan, AIA, director of information technology of Kohn Pedersen Fox Associates, reports:
"The World Trade Towers, visible from any vantage point in our neighborhood, had always loomed over us as endearing landmarks and symbols of New York City, and as representations of late 20th century New York architecture. The events of the past week have touched the psyche of our neighborhood in profound ways.
"Greenwich Village was closed and secured on Tuesday afternoon September 11th, with vehicle access denied, stores and schools closed, people on the streets, fighter jets flying overhead. Our residential street was continually busy with racing ambulances for the first two days of the disaster — 10 to 15 at a time — literally all day and night. The steady sound of sirens and racing rescue vehicles were constant reminders that we were in the midst of something extraordinary, and horrifying.
"A disturbing quiet overtook the neighborhood on the third day, anticipating the grim news of a decline in locating injured victims. The racing rescue vehicles and wailing sirens were replaced by a pervasive and telling odor of burning debris permeating the neighborhood and our homes. Air Force jets and police helicopters continued to fly overhead at regular intervals, yet at street level all was unusually quiet.
"Looking south, a disturbing void reminds us of the horror of last week. Throughout the city, there are fliers with photographs of missing victims posted on bus shelters, light poles, and buildings that are constant reminders of how deeply this disaster has pervaded everyday life. This is a disquieting and distressing time — one that has touched us deeply and will affect each day of our lives in New York for many years."
In New York and elsewhere, thousands of problems must be solved before we can return to normal life. One of these is the ongoing problem of hate crimes against immigrants and Americans of Middle Eastern origin. Unfortunately, there are too many people who may allow feelings of revenge to override fairness.
Paul Taylor, president of the National Organization of Minority Architects (NOMA), is using his position of leadership to remind our profession how they can help. In inviting architects to the NOMA Annual Conference in November, he writes:
In haste and in grief journalists and victims have inappropriately equated terrorists with Arabs and Muslims. This is a dangerous, unjust, and intolerable form of racism. It is now time for NOMA to play a role in the healing of America.
We want Arab-American and Muslim architects to know that we embrace you as friends. We extend to you a special invitation to our conference, where NOMA will demonstrate to the rest of the country how not only to tolerate diversity but to celebrate it. September 11, 2001 was a wake up call for Americans; now is the time for the profession of architecture to wake up and loudly exclaim that everyone is welcome.
In the 1960s, Minoru Yamasaki, architect of the World Trade Center, and himself a minority architect, also expressed the significance of humanism:
The World Trade Center should, because of its importance, become a living representation of man's belief in humanity, his need for individual dignity, his belief in the cooperation of men, and through this cooperation his ability to find greatness.
ArchitectureWeek joins NOMA and Yamasaki in calling for a spirit of humanity and diversity. In that spirit, as the United States prepares for war against a shadowy enemy, let Americans and our friends worldwide rally around these words of the pledge that helps define our nation: "with liberty and justice for all."
About the World Trade Center
About the Pentagon
AISC to Investigate World Trade Center Collapse
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