"Since 2008, the U.S. Department of Homeland Security (DHS) Science and Technology (S&T) Directorate's Infrastructure Protection and Disaster Management Division (IDD) has been working to develop different methods for the rapid evaluation of significant damage to buildings resulting from explosive attacks in large urban centers. For this study, the streetscapes of the New York City Financial District were modeled to represent the surfaces of all the buildings and the geometry of all the streets and alleys. Extensive Computational Fluid Dynamics analyses were performed for different size explosive threats and the results were stored in the UBT [Urban Blast Tool]. Nonlinear explicit dynamic finite element analyses were performed for representative structures to determine the effectiveness of the simplified methods to evaluate the potential for progressive collapse."
United States. Dept. of Homeland Security: http://www.dhs.gov/