When recovery workers sifted through the 1.8 million tons of debris, personal belongings, and human remains at the World Trade Center, they were trying to achieve closure for grieving family members and friends of victims. On another level, though, they were just beginning to embark on a mission that could provide at least a glimmer of good from the tragedy: collecting evidence that would ultimately make high rises and other buildings more structurally sound and secure.
Three and a half years after 9-11, building codes are only just starting to reflect lessons learned from the World Trade Center (WTC) collapse. More movement is likely, however, as further concrete information is gathered about the design elements that did not perform as expected or that hindered rescue and evacuation efforts. One catalyst for these changes is a detailed report on the WTC collapse expected to be released this month from the National Institute of Science and Technology (NIST).
The report, more than two years in the making, is part of an ongoing NIST project that seeks to construct a set of well-grounded data to serve as a foundation for building high rises with improved structural integrity, better fireproofing, and enhanced evacuation capabilities.
In addition, the final NIST report is expected to address some issues not directly tied to 9-11 lessons, such as the effects of winds on tall buildings and the adequacy of wind-load standards for these buildings, says NIST's Dr. Shyam Sunder, who heads the World Trade Center investigation team. Recommendations will also address construction hazards and natural hazards, such as hurricanes.
The recommendations will be specific in terms of a building's expected performance, says Sunder, but not with regard to how that performance should be accomplished or what materials should be used. It will then be up to architects, designers, engineers, code writers (see "Model Makers," below), and local authorities to take the recommendations to the next level. The following overview looks at the progress made since 9-11 and at how future building designs are likely to evolve to meet the terrorist threat.