Henri Sullivan's classic and now somewhat worn clichÃ© adage came to mind when I recently participated in the Building Security Symposium, sponsored be the Architectural Engineering Institute, the Steel and Ornamental Metal Institute of New York and the Infrastructure Security Partnership at the McGraw-Hill conference center in New York City. The trust of the symposium was to review available design options and risk analysis for an effective resistance to terrorist threats. Buildings with simple geometric shapes and clear lines are obviously less vulnerable to the impact of dynamic blast loads, than the ones with intricate and often convoluted shapes of architectural expression.
In addition to forestalling progressive collapse, protection from flying debris, primarily broken glass, is another important challenge of hardening, which can be accomplished with specialty replacement windows and installation of blast curtains.
The goals of a security plan should include the three dees:â€Detection, Deterrence and Delay.â€ To that end provide for physical control elements of building and perimeter access, including clear zones and lighting. Building and perimeter access for both pedestrians and vehicles are best controlled by closed-circuit television, electronic access, alarm and intrusion detection systems, vehicle gate control, and security monitoring with operational procedures. One should also consider such low cost options as diversion and camouflage. The typical terrorist most likely will move on if the target appears well protected or of little strategic value.
Clear zones, fencing, and proper lighting are required around building entrances, parking areas, and walking paths. This is not to say that they should be void of landscaping, but landscaping and planting need to be arranged to allow full view of potentially critical areas. When planning for a new building or facility in todayâ€™s climate, the potential of a terrorist threat should be considered, although it is impractical to design a civilian structure to remain undamaged from a large explosion. The protective objectives are therefore related to the type of building and its function.
For an office, retail, residential, or light industrial building where the primary assets are its occupants, the objective is to minimize loss of life. Because of the severity of large scale explosion incidents, the goals are by necessity modest. Moreover, it is recognized that the building will be unusable after the event. This approach is considered a damage-limiting or damage-mitigating approach to design. To save lives, the primary goals of the design professional are to reduce building damage and to prevent progressive collapse...