Recommendation 8.19: Research should be done to determine the most expeditious means for integrating performance standards with building codes to cover technologies that resist blasts, impacts, and the consequences of fire. This could take a similar form to what was recently employed by the National Earthquake Hazards Reduction Program (NEHRP) in its guidelines for seismic design.
This program should be led by the federal government, perhaps NIST or selected national laboratories. The insurance industry should be a significant participant in this work. The fire and blast tests should be planned and performed under the oversight of the National Fire Protection Association. Objective evaluation of results by independent reviewers is an important step towards facilitating the efficient application of new knowledge and procedures in codes and standards.
Performance standards for dealing with terrorist attack require a probabilistic risk assessment (PRA) approach similar to what has been adopted for earthquake hazards. In simplified terms, risk is the product of the probability of an occurrence times its consequences.
One of the obstacles to developing a risk-based methodology for predicting losses from terrorism is the (thankfully) sparse database of significant events. But in the mid-1960s, when PRA was first developed for seismic risk, the relevant databases and supporting geological knowledge were also much less complete than they are today. However, the idea became very productive once the data were collected. For the moment, an initial resource for terrorism is the databases, maintained by the FBI and ATF, of domestic incidents involving explosives. For example, the FBI Bomb Data Center General Information Bulletin 97-1 catalogs the 1997 domestic bombing incidents with statistics on actual bombings, attempted bombings, explosive bombings, incendiary bombings, and breakdowns by region, state, and target.
It has been suggested, without supporting evidence, that older, heavier buildings may be inherently better able to withstand some types of terrorist attack than modern ones. PRA is an appropriate framework in which to examine this question. Risk modeling can also address the economic implications of alternative design requirements—for example, if resistance to progressive collapse became obligatory for modern lightweight buildings—and it is an appropriate framework for showing the insurance and reinsurance industries how blast engineering mitigates risk.
Recommendation 8.20: Universities and the national laboratories should conduct research on the applicability of a PRA risk-modeling approach for quantifying the expected performance of blast- and fire-resistant designs.
A better understanding of air movements and mixing in HVAC systems could lead to improved designs for lowering vulnerability to toxins.