March 01, 2013
Design to Mitigate the 1-in-100 Year Meteor Storm!
by Brian Katz
Last month I had the opportunity to attend the 2013 Building Innovation Conference hosted by the National Institute of Building Sciences (NIBS) in Washington D.C. One conference session that was of particular interest to me was hosted by the Multi-Hazard Mitigation Council. Presentations and workshops focused on the hazards confronting our country's building inventory and infrastructure including floods, hurricanes, earthquakes, fires, attacks with explosive weapons, and even deterioration. The shared sentiment of many design professionals, policy makers, and academics present at the conference was discontent with the extent to which "standard of practice" design and public policy are rising to meet the challenge of mitigating hazards that are causing more damage than ever before in this country. Key discussions highlighted the need for broader design approaches to mitigate known hazards on a holistic level rather than on a threat-by-threat basis. This type of design would provide the context to achieve higher levels of building performance and would help construct communities that embodied resilient design principles – resist, respond to, and recover from extreme events. Despite the excitement surrounding these conference sessions, I couldn't help but feel that even with a stronger footing to confront mitigation of multiple known hazards, there would always be unknown threats looming in the distance.
Fast forward one month. With the talk of hazard resistant design still fresh in my mind, the world watched as a meteor impact decimated central Russia, injuring hundreds and damaging thousands of buildings. NASA reports on the meteor impact likened it to an explosion equal to that of 300,000 tons of TNT. That is nearly 75-times the amount of TNT estimated to have been used in the bombing of the Alfred P. Murrah Federal Building in Oklahoma City! Attempting to put this astrological event into the context of natural disasters, NASA described it as a 1-in-100 year event. This estimation places the meteor explosion on the same level, with respect to return period, as most design basis seismic and wind events currently considered by state building codes. The solution seems simple enough; I just need to add the 1/100 year meteor impact event to the liturgy of design basis loading currently present in structural design! However, short of burying our communities deep underground, there seem to be few solutions to the design problems posed by mitigating this hazard scenario. What then is the solution? How do engineers provide a truly hazard resistant design in a world full of uncertainty?
Although radical, one direction to set our sights on was featured in a review of Nassim Nicholas Taleb's book "Antifragile: Things that Gain from Disorder" in the November 2012 issue of The Economist. In his first book, Taleb discussed concepts of fragility, which are widely present in performance-based design approaches. Structural engineering based on system fragility essentially provides the framework to assess building response to a known initiating event and improve the design as needed to achieve desired performance. Antifragility resides at the opposite end of the spectrum, providing the context to design a system to be in a position where the unexpected allows improvement, where the potential gains from a surprising event outweigh the potential losses.
I'll be the first to admit that this sounds exciting in theory but seems difficult (at best) to translate into implementable design methods. However, current design approaches are clearly lacking an ability to cope with the unexpected. Perhaps it is time to confront the problem from the opposite end and explore the uncertain aspects of design rather than resolve them with a series of design assumptions confirmed by building code language.