When determining the architecture, designing and carrying out the construction of a building, safety aspects must be considered. An adequate structural system to resist seismic forces or wind pressures, as well as adequate treatment for fire protection, are just some of these safety aspects. However, protection against a terrorist attack is often not considered among these security systems. Despite its devastating effects, this omission is due to the fact that the likelihood of an attack on a given building is extremely low.
Some countries are working on regulations to ensure that the architecture, design and construction of buildings and facilities address, in coordination with other safeguards, this structural safety requirement. In the US, the Federal Emergency Management Agency (FEMA) plans to introduce guidance that addresses the full spectrum of hazards that threaten a building, from earthquakes to explosions.
One of the issues FEMA examined in its studies was the possibility of applying lessons learned in seismic safety to blast protection. After all, FEMA was aware of the similarity between seismic loads and blast loads in a building. For example, both phenomena impose external horizontal forces on the structure within a short time frame.
The results of these studies clearly indicate that the design, architecture and construction of a seismically safe building will provide a significant level of safety also against explosions. This does not lead FEMA to conclude that the two safety systems are equivalent. This is partly because of the large number of uncertainties in predicting a terrorist attack. This is clear from the FEMA publications: Phase 1 Study: Performance Analysis of Reinforced Concrete Strengthening Systems Applied to the Murrah Federal Building Design, FEMA 439A (Washington, DC), December 2005, and Phase 2 Study: Performance Analysis of Structural Steel Strengthening Systems, FEMA P-439B, November 2010.
By Jean Carlos Soto, Senior Structural Engineer, Amusement Logic Architecture Dept.
