All western democracies are now acutely aware of the apocalyptic consequences of a well-orchestrated attack on high-profile government facilities and other related targets. Many of these buildings are historical, ornate, listed and constructed using traditional techniques. Many of the modern retrofitted reinforcement techniques used to protect these structures against terrorist attacks are unsightly, intrusive or inappropriate. However, security specialists are well aware that while there might be little that can be done to defend a building against an aircraft attack, much can be done to defeat the more traditional car bomb and bullet. The methods available to the structural engineer to strengthen existing structures and provide resistance to the effects of a blast attacks are discussed in this paper.
The design of civilian or commercial buildings to withstand the effects of a terrorist blast is unlike the design of military installations or the design of embassy buildings. The objectives of the “Structural Engineering Guidelines” for the Design of New Embassy Buildings are to prevent heavy damage to components and structural collapse. Adherence to the provisions of the guidelines will minimize injuries and loss of life and facilitate the evacuation and rescue of survivors. The blast-protection objective of any commercial or public building must be similar to those of embassy structures, that is, to prevent structural collapse, to save lives, and to evacuate victims.
Architectural and structural features play a significant role in determining how the building will respond to the blast loading. These features can include adjacent or underground parking, atriums, transfer girders, slab configurations, and structural-frame systems. The keep-out distance is vital in the design of blast resistant structures since it is the key parameter that determines the blast overpressures that load the building and its structural elements. The degree of fenestration is another key parameter as it determines the pressures that enter the structure. The smaller the door and window openings the Embassies and military structures occupy secure sites with substantial keep-out distances better protected the occupants are within the structure. Following these key parameters,