7.2 Damage to Structures
63
presence (or absence) of radioactivity must be aware of the potential for structural
damage that can make the building unsafe to enter and unsafe to work in the vicinity
of [5].
Glass that is blown into a room can pose a hazard to those inside the room—it
can cause lacerations ranging from minor to life-threatening. But that is not the only
hazard posed by glass; the blast can also cause sheets of glass on the exterior of newer
buildings to fall to the ground where it can injure or kill people at street level—not
just by causing lacerations, but also due to the weight of heavy panes of glass falling
from a height. A pane of double-glazed residential glass weighs about 20 kg per
square meter [16] so a window that is two meters wide and three meters in height
will weigh 120 kg. The impact of even a portion of this pane falling from a height
of several tens or hundreds of meters can be fatal.
Similarly, decorative and other features can be blown off by the blast, or can be
weakened or loosened enough to break loose and fall at a later time. These, too, can
pose a threat to anyone below.
Thus, blast damage to structures can pose a risk to persons inside the buildings
who might be injured by flying glass or who might be trapped in a structure that
collapses at some time after the explosion. In addition, there is a risk to those outside
the building who must also be concerned about unstable structures and broken glass
(in this case, falling on them from above), as well as pieces of the building falling
from above (Fig. 7.1).
7.3 Damage to Utilities
The blast and shock from a bomb affect more than buildings; they can topple utility
poles or can be transmitted through the ground to damage or rupture subsurface
utility lines. In addition, collapsing buildings can bring down utility poles or, if they
are sufficiently heavy and fall far enough, debris can penetrate far enough into the
ground to sever utilities.
Explosions do more than create shock and blast waves, they also excavate materials they are in contact with—they create craters. The volume of material excavated
by an explosion is roughly proportional to the energy released by the blast [7] so the
craters formed by large explosions are deeper and wider than those formed by smaller
explosions in the same material. The other controlling factor is the strength of the
material being cratered; stronger, denser, more consolidated, and more competent
materials require more energy to produce a crater of a given size compared to materials that are lighter, weaker, or more granular. Craters are more than just holes in
the ground; a crater that runs beneath a building can contribute towards destabilizing
the building, while the formation of the crater itself can also damage nearby utility
lines, or lines that pass through the volume of the crater. Thus, a crater can produce a
risk (or collection of risks) that will continue until they are addressed and resolved.
A utility line that passes through the volume of a crater might or might not be
ruptured by the explosion that formed the crater. However, even if the line appears to
63
presence (or absence) of radioactivity must be aware of the potential for structural
damage that can make the building unsafe to enter and unsafe to work in the vicinity
of [5].
Glass that is blown into a room can pose a hazard to those inside the room—it
can cause lacerations ranging from minor to life-threatening. But that is not the only
hazard posed by glass; the blast can also cause sheets of glass on the exterior of newer
buildings to fall to the ground where it can injure or kill people at street level—not
just by causing lacerations, but also due to the weight of heavy panes of glass falling
from a height. A pane of double-glazed residential glass weighs about 20 kg per
square meter [16] so a window that is two meters wide and three meters in height
will weigh 120 kg. The impact of even a portion of this pane falling from a height
of several tens or hundreds of meters can be fatal.
Similarly, decorative and other features can be blown off by the blast, or can be
weakened or loosened enough to break loose and fall at a later time. These, too, can
pose a threat to anyone below.
Thus, blast damage to structures can pose a risk to persons inside the buildings
who might be injured by flying glass or who might be trapped in a structure that
collapses at some time after the explosion. In addition, there is a risk to those outside
the building who must also be concerned about unstable structures and broken glass
(in this case, falling on them from above), as well as pieces of the building falling
from above (Fig. 7.1).
7.3 Damage to Utilities
The blast and shock from a bomb affect more than buildings; they can topple utility
poles or can be transmitted through the ground to damage or rupture subsurface
utility lines. In addition, collapsing buildings can bring down utility poles or, if they
are sufficiently heavy and fall far enough, debris can penetrate far enough into the
ground to sever utilities.
Explosions do more than create shock and blast waves, they also excavate materials they are in contact with—they create craters. The volume of material excavated
by an explosion is roughly proportional to the energy released by the blast [7] so the
craters formed by large explosions are deeper and wider than those formed by smaller
explosions in the same material. The other controlling factor is the strength of the
material being cratered; stronger, denser, more consolidated, and more competent
materials require more energy to produce a crater of a given size compared to materials that are lighter, weaker, or more granular. Craters are more than just holes in
the ground; a crater that runs beneath a building can contribute towards destabilizing
the building, while the formation of the crater itself can also damage nearby utility
lines, or lines that pass through the volume of the crater. Thus, a crater can produce a
risk (or collection of risks) that will continue until they are addressed and resolved.
A utility line that passes through the volume of a crater might or might not be
ruptured by the explosion that formed the crater. However, even if the line appears to