One of the primary concerns for structures that may be exposed to higher threat levels of terrorism is the ability to protect against structural damage and personal injury that is incurred as a result of an intentional blast. In the case of terrorism, there is also reason to take into account ballistic effects; explosives may be laced with projectiles. It is obvious that there is no such idea as “one size fits all” in reference to such levels of protection. It is therefore necessary for a team of trained specialists to perform a threat assessment of the structure. Some of the metrics that will be taken into account will include, but are not limited to:
1. Size of the structure
2. Static load capabilities
3. Current strength
4. Existing reinforcements
5. The number of windows
6. Frequently trafficked areas
After these and other variables are considered, a report will be issued that is intended to outline the options that are best suited.
Structural Integrity
As seen in the Oklahoma City bombing, the structural integrity of a building has much to do with its ability to withstand a considerable external blast. It should be obvious that retooling an entire complex is logistically impossible and not the most cost-effective solution. Also, there may be levels of discretion that are required in public areas. It is for these reasons that types of reinforced wire are frequently recommended to help strengthen existing wall and columns. Also, protective coatings can allow a wall to withstand the force of an explosion up to twenty times more than in an untreated wall. Once again, both solutions are intended as forms of blast mitigation as opposed to an elimination of the explosive effects entirely.
Curtain Protection
A major concern is parts of a building that will naturally be more susceptible to the effects of a blast and/or additional projectiles. These areas include windows and similar openings. In the case of windows, this is quite important, for the glass itself can travel at hundred of miles per hour and result in grievous bodily harm. One popular solution of blast mitigation in this is the use of safety screens that can be placed on the inside of an existing window. These will absorb a considerable portion of the blast; resulting in less internal overpressures. Also, they will contribute to protection levels by blocking debris that may otherwise entire the structure and cause further damage. This is another cost-effective option to help protect lives and property.
Blast mitigation is a complex concept with equally complex solutions.
