FEMA 453 Design Guidance for Shelters and Safe Rooms

2.4 neW cOnStructiOn
The design of new buildings to contain shelters provides greater
opportunities than the retrofit of existing buildings. Whether
the entire building or just the shelter is to be resistant to the
explosive terrorist threat may have a significant impact on the
architectural and structural design of the building. Furthermore,
unless the building is required to satisfy an established security
design criteria, the weight of explosive that the building is to be
designed to resist must be established by a site-specific threat and
risk assessment. Even so, given the evolving nature of the terrorist
threat, it is impossible to predict all the extreme conditions to
which the building may be exposed over its life. Therefore, even
if the building is not to be designed to resist any specific explosive
threat, the American Society of Civil Engineers Minimum
Design Loads for Buildings and Other Structures (ASCE-7) requires
the building to be designed to sustain local damage without the
building as a whole “being damaged to an extent disproportionate
to the original local damage.” The building can therefore be designed
to prevent the progression of collapse in the unlikely event
a primary member loses its load carrying capacity. This minimum
design feature, achieved through the indirect prescriptive method
or direct alternate path approach, will improve the structural
Structural deSign criteria
Figure 2- 0
layers of defense
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