As the nation solemnly marks the 20th anniversary of the 9/11 attacks, we’d like to take a moment to thank a very special group of people who answered the call and offered their expertise in a time of great need: structural engineers.
As first responders combed through the debris at ground zero, engineers, many of whom were affiliated with the Structural Engineers Association of New York or other member organizations of the National Council of Structural Engineers Associations, kept them safe by ensuring that the partially collapsed structure was sound as excavations progressed in precarious conditions. In fact, during the search for victims and clean-up, the Occupational Safety and Health Administration identified more than 9,000 hazards; though there were a few injuries, none was life-threatening. This is a remarkable achievement given the nature and complexity of the work, and structural engineers played a major role by using their unique skills and knowledge to help others do what they do best–a true demonstration of the unity and teamwork that marked the immediate response to the attacks.
“Providing specialized structural engineering knowledge that assists first responders in determining overall building safety when tragedy strikes lies at the core of the mission for NCSEA and its Member Organizations,” said NCSEA President Ed Quesenberry, SE, PE. “NCSEA is extremely proud of SEAoNY for their dedicated, immediate response to the tragic events of 9/11. We still mourn the nation’s loss two decades later and stand ready to serve our communities into the future.”
Meanwhile, other teams of AEC professionals sprang into action to analyze how damage from the plane strikes led to degradation of the larger structural system and the eventual collapse of the North and South Towers as well as 7 World Trade Center (which was damaged by the collapse of the Twin Towers and subsequent fires).
Within a year, an assessment team formed by the American Society of Civil Engineers, its Structural Engineering Institute, and FEMA had completed the first technical report, and a group led by the National Institute of Standards and Technology followed suit with detailed analysis.
“ASCE was honored to play even a small role in the response to this tragic event, and on this anniversary, we join the nation in mourning and remembrance,” said ASCE Executive Director Tom Smith. “We are grateful to the structural engineers and others who stepped up without hesitation to contribute their expertise to assist first responders in the recovery effort. From that day forward, ASCE and its members have been committed to advancing the profession’s technical knowledge of how these buildings performed in hopes of making future buildings safer.”
Other groups, including the American Institute of Steel Construction and the International Code Council, incorporated the results of those studies and other research on robustness and resilience into updates to building specifications and other standards.
For instance, AISC’s Specification for Structural Steel Buildings now includes structural integrity requirements that are a direct result of those studies, and other building codes strengthened non-structural elements (like battery-powered lighting and photoluminescent strips on stairs) specifically intended to help a building’s occupants respond well in case of an emergency that would require them to either shelter in place or evacuate.
Today, the place where structural engineers and first responders worked together on rescue and recovery efforts is home to new buildings that are, themselves, the result of 20 years of reflection and improved understanding.
“That 20-year progression of the site is built on a 20-year progression from being shocked, learning from it, figuring out the lessons that we needed to embody in the codes, and buildings being built today actually using those lessons,” said AISC President Charles J. Carter, SE, PE, PhD. “It’s a transformation of our understanding and our methods and our approaches–the background that’s embodied in those buildings in addition to all the other buildings that are built today.”
