A History of Research and a Review of Recent Developments

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Table 8.1
It is worth noting that, according to this experimentally based information,
the safe distances were directly proportional to thickness, and increases in
distance were very roughly proportional to the square root of bomb size
increases. It was generally assumed that for conventional blast the period of
vibration of a brick structure would be at least 10 times greater than the
duration of the pressure pulse, and that structural response could be calculated
without the need to resort to single degree of freedom methods. However, for
a nuclear blast the fundamental period of the structure could be less than the
blast duration, and more complex methods of establishing structural response
were necessary. Ultimate strength calculations for brick panels were based on
yield line theory for slabs, using an ultimate stress in bending of 1.5 N/mm 2
and a modulus of Elasticity of 7000 N/mm 2 .
Most of the information given above can be roughly assumed to apply to
edge supported brick walls measuring 8 ft square, but in the case of nuclear
blast the destruction of brickwork is usually related to the complete destruction
of brick houses. The results of nuclear tests in the early 1960s suggested that
for a conventional brick dwelling house a nuclear explosion would cause serious
damage at a distance equivalent to a peak overpressure of about 3.5 psi.
Complete destruction would occur at a peak overpressure of 5 psi.
Table 8.2
The effects of explosive loading