1.2 Contents and Organization
This course provides basic qualitative and descriptive information characterizing potential terrorist threats: the effects of terrorist-caused explosions or releases of chemical, biological, and radiological (CBR) agents; and measures that can be taken to limit and mitigate their impacts on buildings and their occupants.
Because explosive attacks are expected to remain the dominant terrorist threat, most of the guidance in the document relates to explosions and limiting their effects. In addition to descriptive information and guidance, each chapter identifies references for further reading. Chapter 2 focuses principally on bomb (explosion) threats, likely targets, and likelihood of occurrence. Weapons effects are described in Chapter 3, which discusses blast pressure waves, initial blast forces, and the decay of these forces with time and distance. Chapter 4 focuses on damage caused by explosions, including damage mechanisms for various building elements and systems, including both structural and nonstructural components. Topics include (1) progressive collapse, (2) comparisons with forces imposed by other extreme loads, such as earthquakes and wind storms, and (3) the potential extent and distribution of deaths and injuries resulting from various damage mechanisms. Design approaches to limit or mitigate damage caused by bomb attacks are described in Chapter 5. Goals include preventing collapse (at least until the building can be fully evacuated) and reducing the effects of flying debris. Security measures described include: (1) preventing an attack, (2) delaying an attack, and (3) mitigating the effects of these attacks.
The heart of the document is Chapter 6, which contains extensive qualitative design guidance for limiting or mitigating the effects of terrorist attacks, focusing primarily on explosions, but also addressing chemical, biological, and radiological attacks. Checklists of mitigation measures are provided at the end of each major section. Site and layout design guidance is provided in Section 6.1. Important concepts are stand-off distance from the perimeter property line, controlled access zones, and anti-ram barriers, which can be either passive or active. Section 6.2 describes architectural issues and attributes affecting the impact of explosions on buildings. The primary focus is on building shape, placement, exterior ornamentation, and the functional layout of the interior. Structural design issues are discussed in Section 6.3. Topics include (1) methods to prevent progressive collapse; (2) the selection of a building structural system, including desirable attributes of the system; (3) structural layout (the placement of structural elements); (4) design methods, including the relationship between security design and design for conventional loads; and (5) the design of critical structural elements, focusing on the exterior frame, roof system, floor system, interior columns, and interior walls. Section 6.4 addresses the building envelope; i.e., exterior walls and cladding, window systems, and other openings. Specific guidance is provided on exterior wall and cladding design. Window design is given special consideration, including glass design, mullion design, and frame and anchorage design. Guidance is also given on wall design, multi-hazard considerations, and the design of other openings (doors and louvers). Issues relating to the design and placement of mechanical and electrical systems are described in Section 6.5. Topics addressed include emergency egress routes, air intakes, emergency power systems, fuel storage, ventilation systems, the fire-control center, emergency elevators, the smoke and fire detection and alarm systems, the sprinkler and standpipe system, smoke-control systems, and the communication system. Finally, Section 6.6 addresses issues specific to chemical, biological, and radiological protection. Issues discussed include air intakes, mechanical areas, return air systems, vulnerable internal areas (lobbies, loading docks, and mail sorting areas), zoning of HVAC systems, positive pressurization, air-tightness, filtration systems, detection systems, management of emergency response using the fire/HVAC control center, and evolving technologies for CBR prevention.
Chapter 7 discusses special considerations for multi-family residential buildings, buildings that include retail uses, and light-industrial buildings. Chapter 8 discusses cost issues, including some general suggestions on prioritizing potential security enhancements.