Chopter 4
BLAST EFFECTS
The blast-effect program consisted of five projects under the categcries of structures,
crater survey, tree-stand studies, and minefield clearance. Within these categories,
the principal planned objectives of Program 3 were to:
1. Obtain further data on structural loading under air~blast conditions, for the pur»ose of developing prediction techniques applicable to the calculation of structural responseand consequent damage from high-yield nuclear devices (Project 3.1).
2. Determine the dimensions of the apparent craters furmed by Shots 1, 3, and 4,
in order to assist in tae prediction of the crater produced by a high-vield nuclear weapon.
he two situations of particular interest on Castle were a surface burst on land and a
surface burst in relatively shallow water (Project 3.2).
3. Obtain data on the blast effects on three natural tree stands in support of siudies
on blast-damage prediction to forested areas. These were to provide a method of uamage
assessment to material and personnel, knowledge of the amount cf cover a forest afords,
and the impediment to treop movements through or out of a forested area after a ferestdamaging detonation (Project 3.3).
4. Determine the effects of a surface-detonated nuclear device on a planted sea minefield (Project 3.4).
An additional objective was added during Castle to provide for tie documentation of
damage inflicted upon miscellaneous structures from the unexpectedly high vield of Shot 1
{Project 3.5).
4.1
STRUCTURES PROGRAM
The structures program consisted of a planned Project 3.1, in which a 6-by-6-by-12foot rigid concrete cubicle was instrumented for blast loading, and an unplanned Project
3.5, which consisted of documentation of unexpected damage to structures from Shot 1.
Until late in the planning stage, it had been intended to reinstrument a test structure
remaining from Operation Greenhouse—-a multistory building 26 feet in height, 196 feet
in width, and 52 feet in length, sectionalized into various types of construction (Army
Tests Structure 3.1.1). It was planned to perform limited rehabilitation of the struciure,
to augment the existing gage mounts with mounts to obtain more corner and edge ijoading
detail, and to make limited use of displacement gages. A change in cetonation sites
made it necessary to abandon this plan, and adopt instead a different approach (see Appendix).
Both the original and final plans for Project 3.1 were modest in scope, since construc-
tion costs in the EPG were very high, all construction was difficult, aad land area suit~
able for a structures program wasvery limited. In addition, no extensive structures
program could be justified until the extensive data obtained at Upshot-Knothole had been
analyzed, a task which was just being initiated when decisions on the Castle program had
to be made.
Accordingly, Castle Project 3.1 was designed to provide blast-loading data only on the
rigid concrete cubicle (Figure 4.1). The cubicle size and gage locations were determined