A History of Research and a Review of Recent Developments
A History of Research and a Review of Recent Developments
A History of Research and a Review of Recent Developments
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The stability <strong>of</strong> masonry walls under the action <strong>of</strong> blast from conventional<br />
explosives was examined experimentally in a series <strong>of</strong> tests in the late 1970s<br />
<strong>and</strong> early 1980s in the USA. Collapse mechanisms were recorded, as well as<br />
the nature <strong>and</strong> distribution <strong>of</strong> debris from shattering walls, <strong>and</strong> a range <strong>of</strong><br />
construction was investigated, varying from load-bearing masonry to reinforced<br />
concrete frames with a masonry infill. These tests were summarised by Rempel<br />
<strong>and</strong> Beck [8.13], who also analysed crushing energy <strong>and</strong> wall rotation.<br />
Attention was also paid to the design <strong>of</strong> explosive storage facilities constructed<br />
<strong>of</strong> masonry, including overpressures to cause incipient failure <strong>and</strong> safe separation<br />
distances between storage facilities <strong>and</strong> neighbouring buildings <strong>of</strong> brick, masonry<br />
<strong>and</strong> prefabricated blocks. The state <strong>of</strong> affairs in the early 1980s was reviewed by<br />
Napadensky <strong>and</strong> Longinow [8.14]. They quoted current US regulations, which at<br />
the time permitted conventional, inhabited buildings to be located at distances <strong>of</strong><br />
40 W 1/3 to 50 W 1/3 ft from an explosives store, where W is the weight <strong>of</strong> explosive in<br />
pounds. For long-duration pressure/duration blast loads that would be experienced<br />
in a nuclear explosion, incipient failure overpressures (where the structure will fail<br />
under any additional load) was given in terms <strong>of</strong> probability <strong>of</strong> failure as follows.<br />
(a) Light commercial buildings with masonry load bearing walls: 2.0; 3.2; 4.9<br />
psi for failure probabilities <strong>of</strong> 10%, 50% <strong>and</strong> 90% respectively.<br />
(b) One-storey masonry load-bearing wall: 1.8; 2.8; 4.6 psi for failure<br />
probabilities <strong>of</strong> 10%, 50% <strong>and</strong> 90% respectively.<br />
Safe separation distances, peak overpressures <strong>and</strong> impulses, for a range <strong>of</strong><br />
non-nuclear explosions, were tabulated by the authors for a range <strong>of</strong> targets.<br />
Excerpts from their survey are given in Table 8.3.<br />
The authors compared the damage, pressures <strong>and</strong> distances with the recorded<br />
effects <strong>of</strong> the Flixborough vapour cloud explosion in 1974. Damage analysis<br />
Table 8.3<br />
Civil buildings 189<br />
(Separation distance in ft; overpressive in psi; impulse in psi ms)